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With the integration of power electronic converters and components, an accurate thermal design becomes essential. Hence, precise thermal models for components are needed for their optimal design. This paper focuses on the development of an analytical model for the design of thermal resistance of planar magnetic cores (PMC). Based on computational fluid dynamic (CFD) simulations, the PMC design thermal resistance variation is studied, according to ambient temperature and level of losses. Then, a polynomial equation is developed to model those variations, and coefficients are deduced for all the sizes of PMC. This analytical model, useful for designers, is finally validated with thermal measurements on a planar transformer prototype.

Schottky-type p-GaN gate Gallium Nitride High Electron Mobility Transistors (GaN-HEMTs) suffer from threshold voltage ( Vth ) instability phenomenon. Both positive and negative Vth shifts are reported when device undertakes the voltage bias, but the impact of this Vth instability phenomenon on device switching behaviors is less investigated. In this study, the drain-source voltage ( Vds ) induced bidirectional Vth shift in hard-switching condition is characterized and decoupled by an H-bridge based double-pulse test (DPT). Subsequently, the influence of Vth shift on switching behaviors is theoretically analyzed and demonstrated through SPICE simulation and experiment, showing how a positive shifted Vth can reduce the device turn-on commutation speed and increase the switching losses, and vice versa. The results suggest that the Vth instability phenomenon should be considered in accurate switching modeling.

In this paper, a methodology is proposed for studying the current collapse effects of Gallium Nitride (GaN) power diodes and the consequences on the dynamic on-resistance (RON). Indeed, the growing interest of GaN based, high frequency power conversion requires an accurate characterization and a deep understanding of the device’s behaviour before any development of power converters. This study can ultimately be used to model observed trap effects and, thus, improve the equivalent electrical model. Using an in-house circuit and a specific experimental setup, a current-collapse phenomenon inherent to gallium nitride semiconductor is studied on planar 650 V—6 A GaN diodes by applying high voltage stresses over a wide range of temperatures. With this method, useful data on activation energy and capture cross section of electrical defects linked to dynamic RON are extracted. Finally, the origins of such defects are discussed and attributed to carbon-related defects.

Schottky contacts on fluorine implanted AlGaN/GaN heterostructure with ideality factor close to unity and low on-voltage threshold are presented in this paper. A SF6 plasma anode pre-treatment followed by a specific low-temperature annealing is also compared to a nonannealed sample. In addition, physical-model parameters are extracted by means of cryogenic temperature measurements to understand the conduction mechanisms involved in annealed diodes, showing better DC performances than their non-annealed counterparts. Furthermore, the annealing induces a decrease of the ideality factor, which sets the fieldenhanced thermionic emission as the main conduction mechanism, and reduces the tunneling reverse current leakage. This effect is attributed to the recovering of the plasmainduced damages.

High-frequency power converters need electromagnetic interferences filters using common and differential mode chokes with low parasitic capacitance to comply with the electromagnetic compatibility standards. This article proposes a modeling method of this capacitance and ways to minimize it. The studied components are ring core inductors with magnetic materials considered as perfect conductors or with high permittivity, such as nanocrystalline material and most Mn-Zn ferrite materials. In comparison to other work in the literature, the proposed approach takes into account the curvature of the turn, in addition to the coating of the core and the insulation layer of the wire. The hypotheses, used in this article to simplify the real geometry, are compatible with two-dimensional (2-D) approaches to compute the parasitic interturns and turn–core capacitances. These capacitances are evaluated thanks to the 2-D finite element method. The obtained model allows accurate evaluation of the effect of turn–core space on the parasitic capacitance, and enables to reduce its value with a limited impact on the volume of the magnetic component.

In order to model GaN-HEMT switching transients and determine power losses, a compact model including dynamic RDSon effect is proposed herein. The model includes mathematical equations to represent device static and capacitance-voltage characteristics, and a behavioural voltage source, which includes multiple RC units to represent different time constants for trapping and detrapping effect from 100 ns to 100 s range. All the required parameters in the model can be obtained by fitting method using a datasheet or experimental characterisation results. The model is then implemented into our developed virtual prototyping software, where the device compact model is co-simulated with a parasitic inductance physical model to obtain the switching waveform. As model order reduction is applied in our software to resolve physical model, the device switching current and voltage waveform can be obtained in the range of minutes. By comparison with experimental measurements, the model is validated to accurately represent device switching transients as well as their spectrum in frequency domain until 100 MHz. In terms of dynamic RDSon value, the mismatch between the model and experimental results is within 10% under different power converter operation conditions in terms of switching frequencies and duty cycles, so designers can use this model to accurately obtain GaN-HEMT power losses due to trapping and detrapping effects for power electronics converters

Due to the high switching speed of Gallium Nitride (GaN) transistors, parasitic inductances have significant impacts on power losses and electromagnetic interferences (EMI) in GaN-based power converters. Thus, the proper design of high-frequency converters in a simulation tool requires accurate electromagnetic (EM) modeling of the commutation loops. This work proposes an EM modeling of the parasitic inductance of a GaN-based commutation cell on a printed circuit board (PCB) using Advanced Design System (ADS®) software. Two different PCB designs of the commutation loop, lateral (single-sided) and vertical (double-sided) are characterized in terms of parasitic inductance contribution. An experimental approach based on S-parameters, the Cold FET technique and a specific calibration procedure is developed to obtain reference values for comparison with the proposed models. First, lateral and vertical PCB loop inductances are extracted. Then, the whole commutation loop inductances including the packaging of the GaN transistors are determined by developing an EM model of the device’s internal parasitic. The switching waveforms of the GaN transistors in a 1 MHz DC/DC converter are given for the different commutation loop designs. Finally, a discussion is proposed on the presented results and the development of advanced tools for high-frequency GaN-based power electronics design.

The new power GaN transistors allow to increase the operating frequency of converters to megahertz range, thanks to their low switching time that is of a few nanoseconds or less. This permits to reduce the values and the volume of the passive components, and enhance the power density of power converters. However, inductors needed for energy storage still take a large volume in converters compared with the others components, because of their weak energy density. Further, high frequency operation require low-losses magnetic materials. In this paper, a design method of PCB inductors is proposed. A flexible ferrite sheet is used to enhance the inductance value and ease the realization of custom-shape devices. The design method of the inductor is based on the optimization of the inductor volume taking into account thermal issues of the magnetic sheets. Also a simulation method is proposed to calculate the equivalent stray capacitance of the inductors. The proposed method provides a losses-volume trade-off that helps designers to optimize the inductor for their application.

The paper investigates the management of drain voltage and current slew rates (i.e., dv/dt and di/dt) of high-speed GaN-based power switches during the transitions. An active gate voltage control (AGVC) is considered for improving the safe operation of a switching cell. In an application of open-loop AGVC, the switching speeds vary significantly with the operating point of the GaN HEMT on either or both current and temperature. A closed-loop AGVC is proposed to operate the switches at a constant speed over different operating points. In order to evaluate the reduction in the electromagnetic disturbances, the common mode currents in the system were compared using the active and a standard gate voltage control (SGVC). The closed-loop analysis carried out in this paper has shown that discrete component-based design can introduce limitations to fully resolve the problem of high switching speeds. To ensure effective control of the switching operations, a response time fewer than 10 ns is required for this uncomplex closed-loop technique despite an increase in switching losses.

Because of trapped charges in GaN transistor structure, device dynamic ON-state resistance RDSon is increased when it is operated in high frequency switched power converters, in which device is possibly operated by zero voltage switching (ZVS) to reduce its turn-ON switching losses. When GaN transistor finishes ZVS during one switching period, device has been operated under both reverse and forward conduction. Therefore its dynamic RDSon under both conduction modes needs to be carefully measured to understand device power losses. For this reason, a measurement circuit with simple structure and fast dynamic response is proposed to characterise device reverse and forward RDSon . In order to improve measurement sensitivity when device switches at high frequency, a trapezoidal current mode is proposed to measure device RDSon under almost constant current, which resolves measurement sensitivity issues caused by unavoidable measurement circuit parasitic inductance and measurement probes deskew in conventional device characterisation method by triangle current mode. Proposed measurement circuit and measurement method is then validated by first characterising a SiC-MOSFET with constant RDSon . Then, the comparison on GaN-HEMT dynamic RDSon measurement results demonstrates the improved accuracy of proposed trapezoidal current mode over conventional triangle current mode when device switches at 1MHz.

Thermal performance of power converters is a key issue for the power integration. Temperatures inside active and passive devices can be determined using thermal models. Modelling the temperature distribution of high frequency magnetic components is quite complex due to diversity of their geometries and used materials. This paper presents a thermal modelling method based on lumped elements thermal network model, applied to planar magnetic components made of EE and E/PLT cores. The 3D model is automatically generated from the component’s geometry. The computation enables to obtain 3D temperature distribution inside windings and core of planar transformers or inductors, in steady state or in transient case. The paper details the proposed modelling method as well as the automated tool including the problem definition and the solving process. The obtained temperature distributions are compared with Finite Element simulation results and measurements on different planar transformers.

In order to better predict the high frequency switching operation of transistors in power converters, parasitic elements of these devices such as resistances, inductances and capacitances must be accurately evaluated. This paper reports on the characterization of a gallium nitride (GaN) packaged power transistor using S-parameters in order to extract the device parasitics. Because the transistor is packaged, a calibration technique is carried out using specific test fixtures designed on FR4 printed circuit board (PCB) in order to get the S-parameters in the transistor plane from the measurement. The proposed method is suitable for a wide range of power devices. In this work it is applied to an enhancement mode GaN High Electron Mobility Transistor (HEMT).The impact of junction temperature on drain and source resistances is also evaluated. According to characterization results, equation-based modeling is proposed for the non-linear parameters. The extracted parasitic elements are compared with reference values given by the device manufacturer.

Improving the operation of power grid and offering new smart applications, the deployment of a supervisory infrastructure is necessary. One solution to transmit data may be based on the Power Line Communication (PLC) technology. It consists in the superposition of the high frequency signals with the electrical signal 50/60 Hz. However, the power grids have not been designed to operate in high frequencies. Therefore, they provide a transmission channel with difficult propagation conditions. This paper deals with the modeling of the MV/LV power transformers in PLC frequencies. The proposed models are based on “lumped model” and “black box model”. They are performed in frequency band from 1 kHz to 1 MHz on SPICE and MATLAB softwares respectively. These models are based on impedance measurements and validated by experimental data. The advantages and drawbacks of each model are detailed from the presentation of modeling method and simulation results. The comparison of the simulation results show that “black box model” offers a good accuracy. The transmission results show that transformers are an important element in PLC studies because it provides significant losses. Moreover, these losses depend mainly on the values of the impedance terminals of MV/LV transformer.

This paper presents a PWM strategy for the cancellation of common-mode (CM) voltage generated by three-phase back-to-back two-level inverters. This method theoretically provides complete elimination of the CM voltage by synchronizing all the commutations of one converter with commutations of the other one, so that the overall resulting CM voltage does not vary. The degrees of freedom of this strategy are studied and an experimental implementation is carried out on a 15kW motor drive prototype to validate the method effectiveness. Taking into account dead-time compensation, measurements in time and frequency domains show that the CM voltage is strongly reduced and that more than 15dB reduction is achieved in a wide frequency range.

Planar magnetic components are promising solutions for the integration of power electronic systems. The leakage inductance of such components plays an essential role in power converters. In this paper, an analytical modeling method for leakage inductance computation is developped for planar components with plasto-ferrite leakage layers. This method is based on the solution of Poisson’s equations for magneto-static using multilayered Green’s functions. The obtained formulations are general and precise and have been validated by numerical tests. Experimental characterizations have been performed on two magnetic components: A planar LLC and planar common mode choke. The obtained results show that with the described method, the static leakage inductance of planar components can be accurately estimated.

The switching of the power semiconductors in static converters is the main source of electromagnetic interferences (EMI). To meet with Electromagnetic Compatibility (EMC) standards, it is necessary to reduce the level of the conducted emissions. This reduction can be achieved by different techniques including the EMI filters whose design is mainly based on the use of ring core inductors. This element is a key point for designing efficient EMI filters, requiring then accurate inductor high frequency (HF) models. Therefore, the present paper deals with the development of a HF behavioral model of inductors, based on electrical equivalent circuit, for an implementation in circuit simulation software. The aim is to provide a robust and adjustable model under small-signal operating conditions for frequencies up to 100MHz. The proposed model considers the frequency dependent properties of the magnetic core material and also includes the parameterization of the electrical equivalent circuit elements with the number of winding turns and dimension of the magnetic core. Simulations results using the obtained inductor model are validated by impedance measurements with two types of magnetic materials: Ferrite and Nanocrystalline

In order to study switching waveforms of a SiCJFET, its inter-electrode capacitances evolution is necessary when the power device is in linear region. In this paper, the reverse transfer capacitance Cgd is at first characterized by the multiplecurrent- probe method and afterwards validated by the measurement with an impedance analyzer. The output capacitance Coss is measured by the same method and compared with the single-pulse characterization, which shows a huge increase of the apparent capacitance values in linear region. The influence of the power transistor internal gate resistor is thus studied, revealing the inter-electrode capacitances measurement difficulties when the power device is in linear region. The characterization results are allowed to finely model the power transistor of which the switching behaviors are validated with the measurement in a buck converter.

With the advantage of high bandwidth and small insertion impedance, a current surface probe (CSP) used to measure switching current waveforms is presented in this paper. Its transfer impedance is characterized and validated by measuring an IGBT switching current that is compared with those obtained with a current probe (CP), a current shunt (CS) and a Hall effect current probe (HECP). Furthermore, by comparing with a CS to measure a GaN-HEMT switching current, it is shown that CSP is able to measure a switching current of a few nanoseconds, while it brings no influence on transistor voltage waveform measurement. The obtained results show that, the use of CSP brings little parasitic inductances in the measurement circuit and it does not bring the connection of the ground to the power converter, which is the case for the CS.

This paper deals the design method of EMI filter associated with buck converter using silicon carbide (SiC) power semi-conductors. It's well known that to comply with EMC standards, EMI filters are necessary. The aim is to propose a design method based on an equivalent electrical circuit. Thus, the first step is the identification of the different elements of the proposed model but also the limits values of the parasitic elements of the passive components which play a major influence on the efficiency of the filters. The main objective is to study the influence of the common mode paths on the design of the filter before and after its installation. A filtering solution is proposed to reduce the high frequency disturbances caused by the fast SiC components. The simulation results obtained with the proposed model are compared with the measurements show the effectiveness of the proposed EMI filter design method.

With the advantage of high bandwidth and small insertion impedance, a current surface probe (CSP) used to measure switching current waveforms is presented in this letter. Its transfer impedance is characterized and validated by measuring an IGBT switching current that is compared with those obtained with a current probe (CP) and a Hall effect current probe (HECP). Furthermore, by comparing with a current shunt (CS) to measure a GaN-HEMT switching current, it is shown that CSP is able to measure a switching current of a few nanoseconds, while it brings no influence on transistor voltage waveform measurement. The obtained results show that, the use of CSP brings little parasitic inductances in the measurement circuit and it does not bring the connection of the ground to the power converter.

This paper focuses on the modeling method of energy cables used in power conversion systems, in the aim of EMC simulation and overvoltage analysis. Based on the node-to-node functions method, A simple frequency-domain model with a reduced number of equivalent impedances is considered and applied to three-wire shielded cables, along with a fast identification method based on a cascaded-cell model. Even though the model eventually includes nonphysical virtual impedances, simulation in frequency domain provides accurate results when compared to equivalent experimental measurements, for various cable lengths and in short simulation times. Time-domain waveforms are then extracted from frequency-domain simulation and confirm the effectiveness of the proposed method in a wide frequency range up to 50 MHz. Finally, a good match has been found between experimental and simulation results of voltage overshoots on a buck power converter system.

Two current probes are designed with the appropriate magnetic material in order to make impedance measurements in High Frequency (HF) using the Current Injection Method (CIM). These probes are then used to measure the common-mode impedance of power converters in real-operating conditions. The characterization of this impedance is required for a correct EMI filter design. In this paper, a simple formulation of the probe transfer impedance, based on S-parameters, is proposed. These probes allow improving the accuracy of impedance measurements in a wide frequency range, up to 100 MHz. The measured impedances of the power converter are then applied in the design of the common mode EMI filter under real operation conditions. The obtained insertion losses of the filter are finally compared with those measured under 50Ω-50Ω

The magnetic material when designing EMI filter determines the inductance value and the parasitic elements that influence the insertion loss effectiveness of the filter. Moreover, the EMI filter characterization is usually realized at low power levels (low current and low voltage). When the EMI filter is subjected to higher currents through its coils, the principal characteristics of the filter (inductance variation with current and frequency) are modified. To account for these variations in the design step, it is useful to take into account the hysteresis model that represents the inductive and dissipative effects. Therefore, in this paper, an approach combining a magnetic hysteresis model together with a concept of material capacitance is proposed. The model is identified from a single turn of flat copper ribbon (STFC) experimental setup. Then, the experimental data are modeled with the proposed hysteretic and capacitive material behavior model (HCM) that is implemented in an equivalent circuit modeling approach, accounting for both the magnetic behavior law together with the "material capacitance". The robustness of the proposed approach is evaluated by comparison and validation with the experiment results, showing good representation of the inductive and partially the dissipative effects

In order to enhance the performance of electromagnetic interference (EMI) filters, it is necessary to identify high-frequency parasitic elements of their passive components, mainly those related to the coupled inductors. Motivated by this issue, in this work a realistic high-frequency model is proposed for the coupled inductors. Actually, using interval analysis in particular the forward–backward contractor, a set-membership algorithm has been developed to estimate systematically the parasitic elements linked with the magnetic components. The main advantages of this algorithm compared to the fitting methods are the values of the estimated parameters are always positive and the corrupted data are taken into account. The comparison of the simulation results and the experimental data allows us to validate the proposed method.

The characterization of voltage-dependent capacitances of power semiconductor devices (diode, MOSFET, IGBT etc.) is very important for modeling their dynamic performances. A measurement method using two current probes has been developed to characterize inter-electrode capacitances of power devices while isolating the measurement devices from the high-voltage DC bias power source. Ciss and Coss are shown to be accurately measured while Crss is not convincing enough. Then an additional current probe is added to improve the method. Crss is shown to be well characterized by this three-current-probe method. This method has been validated using various technologies of semiconductor devices including silicon MOSFET and silicon carbide JFET. The inter-electrode capacitances of power devices can be safely and accurately measured with this multi-probe method even in high voltage.

Power converters with high switching frequency generate conducted electromagnetic interference (EMI) noise. EMI filters are thus widely used to reduce these conducted noises for the compliance with electromagnetic compatibility standards. In this paper, a high-frequency (HF) equivalent circuit model for common mode (CM) chokes used in EMI filters is proposed together with its parameter extraction procedure. This procedure is based on impedance measurements and it incorporates an iterative rational function approximation fitting algorithm to extract the parameters in the model. The proposed model and procedure is applied to a planar CM choke which is used to realize an EMI filter. The simulated results of the filter show good agreement with the experimental ones. This extraction procedure is quite general and it can also be extended to identify the HF model of other passive components.

This paper presents an analytical method for calculating the parasitic capacitances of planar components with 3 dimensions. The calculation is based on the Electric Field Decomposition (EFD) between multi-conductors. 2D formulations used in micro-electronics have been extended to enable the applications on the cases of planar magnetic components. The 3D calculation is then based on an energy approach with the consideration of the magnetic core effects. Prototypes of inductors and coupled inductors allow the validation of this fully analytical approach.

Abstract--- Electromagnetic interference (EMI) filters are main solutions to suppress the conducted emissions from static power converters. For some years, integration techniques for EMI filters have been widely investigated to realize more compact systems. In this letter, a common mode (CM) choke with toroid-EQ mixed structure is presented. This structure is constituted of a toroidal CM choke embedded into an EQ core. The proposed toroid-EQ CM choke presents three-fold advantages. First, it effectively increases the leakage inductance of the toroidal CM choke and hence increases the DM inductance. Secondly, it reduces the parasitic coupling between the choke and the filter capacitors. Finally, the component can be easily fabricated with low cost. Experimental verifications have been carried out to validate the effectiveness of the proposed toroid-EQ CM choke.

This paper deals with a high-frequency modeling method of the coupled inductors used in electromagnetic interference (EMI) filters. These filters are intended to reduce conducted emissions generated by power static converters towards the power grid. To model the EMI filters, it is necessary to identify the various parameters of the passive elements: inductors and capacitors. Because of their major impact on filter efficiency, these elements must be identified with accuracy. In this study, high-frequency model of common-mode-coupled inductors is proposed. The identification of the model parameters is based on the experimental approach. Simulation results of the proposed model are compared to the experimental data obtained using the specific experimental setup. These results made it possible to validate the EMI filter model and its robustness in a frequency range varying from 9 kHz to 30MHz. The proposed high-frequency inductor models will be very helpful for design and optimization of EMI filters, since the high-frequency behavior of the filter mainly depends on magnetic materials used and on the geometrical characteristics of winding.

Turn-on performance of a reverse blocking insulated gate bipolar transistor (RB-IGBT) is discussed in this paper. The RB-IGBT is a specially designed insulated gate bipolar transistor (IGBT) having ability to sustain blocking voltage of the both polarities. Such a switch shows superior conduction but much worst switching (turn on) performances compared to a combination of an ordinary IGBT and blocking diode. Because of that, optimization of the switching performance is a key issue that makes the RB-IGB not well accepted in the real applications. In this paper the RB-IGBT turn-on losses and reverse recovery current are analysed for different gate driver techniques and a new gate driver is proposed. Commonly used conventional gate drivers do not have capability for the switching dynamics optimization. In contrast to this, the new proposed gate driver provides robust and simple way to control and optimize the reverse recovery current and turn-on losses. The collector current slope and reverse recovery current are controlled by the means of the gate emitter voltage control in feed-forward manner. In addition, the collector emitter voltage slope is controlled during the voltage falling phase by the means of inherent increase of the gate current. Therefore, the collector emitter voltage tail and the total turn on losses are reduced, independently on the reverse recovery current. The proposed gate driver was experimentally verified and the results presented and discussed.

In adjustable speed drive applications, the switching of the inverter semiconductors generates common mode currents as well as harmful overvoltages on the motor terminals when long cables are used. Consequently, bulky and expensive input and output filters must be used. This work aims at reducing these disturbances from their origin by using a three-level neutral-point-clamped (NPC) inverter controlled with a new pulse-width-modulation (PWM) strategy. Whereas previous common mode noise-reducing strategies usually generate higher overvoltages than conventional ones, the proposed PWM is able to manage both problems thanks to its internal degrees of freedom.

Pulse-width-modulated (PWM) voltage-source inverters are known to provoke high-frequency disturbances in motor-drive applications, especially when long cables are used. Indeed, the parasitic elements of the cable along with steep voltage transitions due to semiconductor switchings are responsible for conducted electromagnetic emissions as well as high overvoltages on the motor terminals. Therefore, several specific PWM schemes have been proposed in order to reduce these phenomena without requiring large passive filters. However, strategies which reduce common-mode currents (mainly conducted electromagnetic emission) tend to increase the overvoltages generated on the motor. This paper focuses on a new PWM strategy which reduces the common-mode currents generated by three-level inverters. It provides a control algorithm which makes sure that the motor overvoltages never exceed those of conventional strategies, while improving the electromagnetic-compatibility performance of the drive.

This paper deals with conducted ElectroMagnetic Interferences in adjustable speed drive (ASD) systems. For some years, the use of high speed switching power devices in ASDs induces high voltage (dv/dt) and high current (di/dt) variations that excite the parasitic elements of the power circuit, inducing conducted emissions. The advent of these devices has thus generated several unexpected problems, such as premature deterioration of motor ball bearings and high increases in the EMI levels, caused by the circulation of the high frequency currents. In order to evaluate the level of the common mode and the differential mode currents in the ASD system, it is necessary to use a precise model of the PWM inverter, power cable and AC motor that takes into account various phenomena, which appear when the frequency increases. First a PWM inverter and shielded 4-wire power cable model are presented. Then, a new high frequency modeling method of the AC motor is proposed. Finally, the ASD system is simulated and the obtained results are compared to the experimental measurements in the frequency and time domains.

RÉSUMÉ. Cet article présente une nouvelle stratégie de modulation de largeur d’implusion destinée à réduire les courants de mode commun dans les applications de variation de vitesse utilisant un onduleur à trois niveaux de type neutral-point-clamped. Il détaille l’implantation de cette commande par un modulateur à porteuses en dents de scie permettant de contrôler les degrés de liberté apportés par la stratégie. ABSTRACT. This paper presents a new pulse-width-modulation strategy for the reduction of common-mode currents in adustable-speed-drive applications using a three-level neutral-pointclamped inverter. It is implemented through a saw-tooth carrier-based modulator which makes it possible to control the degrees of freedom provided by the strategy.

In power electronics applications, power cables spread paths of conducted disturbances throughout the system. This paper proposes a high frequency modeling method for power cables that takes into account phenomena which appear when the switching frequency of the static converter increases, such as skin effects, proximity effects and dielectric losses. The proposed power cable models are obtained by the series-association of n identical RLCG basic cells. The skin and proximity effects are represented as the impedance of an R-L ladder and the dielectric losses as the admittance of an R-C ladder. The proposed method was successfully applied to a three-wire unshielded cable and extended to a four-wire shielded cable.

— This paper proposes two high frequency modeling methods of asynchronous motor: asymptotical and analytical methods, respectively. Both models use a lumped circuit whose RLC parameters are obtained by experimental measurements in common and in differential mode configurations. The asymptotical method consists in deriving the motor model parameters from the observation of the variations of the motor impedance with the frequency. The analytical method consists in deriving the motor model parameters from mathematical resolution of the electrical circuit equations. The obtained models have been validated in both frequency and time domains.

In adjustable speed drive applications operating at high switching frequencies, common mode and differential mode perturbations may cause premature ageing of electric machines and important electromagnetic radiations. These disturbances are generated by the power electronic converter, but can be amplified by the connection between the converter and the electric machine. This connection is ensured by multi-wire energy cables, shielded or unshielded. Whereas it is easy to find models allowing to simulate the HF behaviour of cables intended to transmit information, the HF models of the cables intended to carry electric power are still to be built. This article deals with HF modelling of an unshielded 2-wire energy cable, which is a first step to multi-wire cable models. A model with distributed constants is proposed and validated in both time and frequency domains, first in a voltage pulse mode and loaded by a pure resistive load, then in an experimental set-up where the cable ensures the connection between an elementary power electronic converter and a load with inductive couplings and stray capacitors.

Adjustable-speed drives involve common-mode voltages, which generate common-mode currents flowing to the ground through stray capacitances of electric machines. These currents are known to provoke premature motor-bearing failures, as well as electromagnetic interferences disturbing neighbor electronic devices. Furthermore, high-voltage applications involve high levels of these conducted emissions, which must be lowered by using bulky and expensive filters. This paper aims at elaborating a new pulsewidth-modulation (PWM) strategy in order to reduce the common-mode currents generated by threelevel neutral-point-clamped inverters. The proposed strategy also provides the ability to balance the neutral point of the dc-bus capacitors. Experimental results both in time and frequency domains confirm that the new PWM improves the electromagneticcompatibility behavior of the drive compared with conventional strategies.

The fast commutation of the modern power semi-conductor devices is the main source of the conducted and radiated emissions generated by the power converters. These devices produce high voltage variations (dv/dt) which excite stray elements of the power circuit and induce high frequency parasitical currents that use the energy cables to be propagated in the whole of the system. In order to study the influence of the power cable characteristics on the level of the conducted emissions, it is necessary to elaborate a precise model of the energy cables, taking into account various phenomena that appear when the frequency increases. This paper proposes a high frequency modelling method of energy cable that takes into account the skin and proximity effects and dielectric losses. The proposed method is applied to the 3-wire unshielded cable and extended to the 4-wire shielded cable. The proposed models are validated in the frequency and time domains.

In Adjustable Speed Drives (ASD), increasing the switching frequency of power devices in PWM inverters induces high voltage variations (dv/dt) leading to conducted emissions at high frequencies which are propagated both through Common Mode (CM) and Differential Mode (DM) in the system. The circulation of high frequency parasitic currents causes several unexpected problems, such as premature deterioration of motor winding insulation and ball bearings. The operating PWM inverter can be reduced to two commutation modes: commutation from diode to transistor associated with diode reverse recovery where the highest dv/dt may occur, and commutation from transistor to diode where dv/dt value depend of the dead time duration that is inserted in the control signals to prevent dc link shortages. This paper deals with the influence of PWM inverter operating commutation types and dead time duration on common mode and differential mode current distribution, showing that both propagation modes may be linked.

The switchings of semiconductor devices are the main sources of Electromagnetic Interference (EMI) in power static converters. However, the use of fast power devices generates high levels of conducted emissions due to the flow of high frequency currents known as common mode (CM) and differential mode (DM) currents. In the power systems, these high frequency disturbances use the power cables to travel and to spread. In order to study the influence of the power cable characteristics on the level of the conducted emissions, it is necessary to elaborate a precise model of the power cables, taking into account various phenomena that appear when the frequency increases. This paper deals with 2-wire unshielded and shielded energy cables using a distributed parameter model which takes into account the skin and proximity effects, and the dielectric losses. The obtained models are simulated and validated (with LT Spice/SwicherCADIII software) in the frequency and time domains.

As the characteristics of insulted gate transistors (like MOSFETs and IGBTs) have been constantly improving, their utilization in power converters operating at higher and higher frequencies has become more common. However, this, in turn, leads to fast current and voltage transitions that generate large amounts of ElectroMagnetic Interferences (EMI) over wide frequency ranges. In this paper, a new Active Gate Voltage Control (AGVC) method is presented. It allows us to control the values of di/dt at turn-on and dv/dt at turn-off for insulated gate power transistors, by acting directly on the input gate voltage shape. In an elementary switching cell, it enables us to strongly reduce over-current generated by the reverse recovery of the free-wheeling diode at turn-on, and oscillations of the output voltage across the transistor at turn-off. In the following sections, the Active Gate Voltage Control in open and closed-loop for IGBT is presented, and it performance is compared with that of a more conventional method, i.e. increasing the gate resistance. Robustness of the AGVC is estimated under variations of dc-voltage supply and transistor switched current.

To day, Adjustable Speed Drives (ASDs) manufacturer’s uses high-speed switching devices such as the Insulated Gate Bipolar Transistors (IGBTs) to achieve higher efficiency, low weight and small size. However, the advent of fast power devices has produced several unexpected problems, such as premature deterioration of ball bearing and high levels of electromagnetic emissions, caused by flowing of parasitic capacitive currents known as common mode (CM) currents. In order to evaluate these leakage currents, a suitable model of the ASD is obtained by the identification of the high frequency spreading paths. In this paper, first the simulations are carried out using the proposed model and compared with experimental results. In the second part, one proposes two methods of reduction of the common mode currents in the ASD system.

The power converter have high voltage and high current switching waveforms that generate Electromagnetic Interference (EMI) in the form of both conducted and radiated disturbances. To reduce this high frequencies emissions, the classical solutions consist in filtering and shielding. In this paper, another approach is used to minimise the EMI generated by power transistors. A new simple control technique for insulated gate transistors is presented which allows to act upon turn-on transition waveforms just as an integrated adjustable snubber may do. This control may be applied to MOSFET or IGBT and allows to reduce the di/dt during turn-on commutation. In a simple elementary commutation cell such as a boost converter, it allows sensible reduction of over-current and high frequency oscillations associated to diode reverse recovery.

L’électronique de puissance utilise des interrupteurs commutant à des fréquences de plus en plus élevées. Les variations de courant et de tension durant les transitions provoquent des perturbations électromagnétiques dans de larges bandes de fréquence. Afin de réduire les émissions conduites et rayonnées générées par les interrupteurs de puissance, un nouveau dispositif de commande appelé CATS (Commande Autour de la Tension de Seuil) permet de contrôler de façon simple les gradients de courant ou de tension lors des commutations des transistors de puissance à grille isolée (MOSFET et IGBT). Dans un premier temps le principe de fonctionnement des commandes CATS/ON et CATS/OFF est présenté en boucle ouverte, puis en boucle fermée. Ce dispositif présente plusieurs avantages comparé à une méthode classique de commande par variation de la résistance de grille. L’efficacité de la commande CATS dans la réduction des émissions électromagnétiques est également mise en évidence.

As switches in power electronic converters operate at higher and higher frequencies, current and voltage transitions result in electromagnetic perturbations over wide frequency ranges. In this paper, a voltage control mode is presented, which is named CATS (Commande Autour de la Tension de Seuil). It allows to control in a simple manner the current and/or voltage rate-of-rise during turn-on and/or turn-off switching of insulated-gate power transistors, by acting directly on the input gate voltage shape. In an elementary switching cell, it allows to strongly reduce overcurrent associated to the reverse recovery of the free-wheeling diode at turn-on, and oscillations of the output voltage across the transistor at turn-off. First, the open-loop voltage control is presented, then the closed-loop voltage control is implemented, thus allowing secure turn-on and turn-off commutations of insulated gate transistors. In the last part, the robustness of this gate-voltage control is estimated under variations of dc-voltage supply and transistor switched current.

La norme CEM 89/336/CEE applicable depuis le 1er janvier 1996 impose des limites sur les perturbations électromagnétiques émises et transmises par les appareils électriques. Pour la plupart des convertisseurs d’électronique de puissance, les interférences électromagnétiques résultent de l’excitation des éléments parasites du circuit par les commutations des interrupteurs fonctionnant à des fréquences de découpage de plus en plus élevées. En particulier, la montée du courant à la fermeture d’un interrupteur est à l’origine du mode d’émission différentiel des interférences ; les gradients de tension à l’ouverture sont quant à eux liés au mode commun. Les méthodes de réduction d’interférences conventionnelles reposent sur le filtrage, le blindage ou l’élimination des chemins de propagation (couplages) entre la source et l’élément perturbé « victime »; tout ceci ne fait que préserver le récepteur des perturbations. Agir sur la source des perturbations, à l’aide d’une commande reprochée adaptée, peut s’avérer à terme une solution tout aussi efficace qu’économique, en limitant le recours aux matériaux de construction absorbants. Après avoir exposé le principe de base de la commande autour de la tension de seuil (CATS), nous exposerons ses qualités expérimentales. Le souci de rendement des convertisseurs a motivé la mise en œuvre du concept au sein d’un système en boucle fermé. Le système bouclé sera confronté, dans ce but, à une méthode de limitation des interférences plus conventionnelle, qui consiste à augmenter la résistance de grille.

Power electronics converters generate conducted electromagnetic interference (EMI) over a wide frequency range. In order to prevent pollution of the electrical network and thus comply with electromagnetic compatibility (EMC) standards, it is necessary to install filters at the input side of converters. The optimal design of these filters requires modeling the entire energy conversion system and using the proposed models in circuit simulations (SPICE, etc.). Depending on whether the conversion system is already implemented or in the design stage, there are several modeling methods. When the system is already implemented, the method that treats the converter with its load as a black-box model, called “Terminal Modeling” is particularly suitable in this case. In this paper, we highlight its limitations and propose a gray-box model to enhance its accuracy and robustness up to 100 MHz.

This work investigates the power GaN-HEMTs switching behaviour differences resulted from usage of two gate driving configurations: single and split outputs. The analysis based on simulation and experimental results show that GaN-HEMTs could switch slower and cause higher switching losses when the split output configuration is used. This is because the output capacitance (Coss) of MOSFETs inside gate driver will be charged during the turn-on process of GaN-HEMTs, and this charging process can reduce the charging speed of input capacitance (Ciss) of GaN-HEMTs. Moreover, the gate resistance and parasitic inductance are the main parameters selected for analysis, and their distribution can amplify this effect by increasing the impedance ratio of turn-on and turn-off loop. This research provides guiding suggestions for gate driver and high-efficiency GaN-HEMTs power module design.

integrated drives are becoming a target for manufacturers aiming at addressing the increasing market of electrical embedded systems, such as e-transportation systems. Anyway, the integration of the power converter inside the electrical machine induces challenges if compactness is required. Additionally to the research of the best choices for the power electronics, electromagnetic, and thermal components, interconnection issues also arise, leading to cope simultaneously with several physical challenges. This paper gives an example of a multidisciplinary approach to propose smart integrated drive solution dedicated to middle power embedded systems.

A new method is proposed in this paper to investigate the influence of current collapse effect on the Id−Vds characteristics of GaN-HEMTs in high voltage region based on a modified H-bridge circuit. The measured Id−Vds characteristics with and without the Vds bias are compared, which shows the effect of charge trapping due to the Vds bias on device Id−Vds characteristics in saturation region. These data will be used for a device model including the current collapse effect in full Id−Vds region.

High-frequency static converters requires inductors, common and differential mode chokes with a low equivalent parallel capacitance. To reduce it, this paper proposes first a semi-analytical model of this capacitance for inductors made with coated ring cores of nano-crystalline material. This model is based on 2D finite element method to compute the turn-turn and turn-core parasitic capacitances, taking into account loose windings. Then the total capacitance is computed thanks to an energetic approach. The model is validated against measurements performed on one core for several numbers of turns. Since the model shows that the capacitance is almost linear with the parasitic turn-core capacitance, specific devices are proposed to increase the distance between turns and core and thus decrease the capacitance. It is demonstrated that a small increase in overall volume allows to divide the equivalent parallel capacitance of a common mode choke by almost a factor of three while increasing its overall volume by only 37%.

The constant growth of electric consumption leads to considerable progress in power conversion. Recent studies have shown that using Gallium Nitride (GaN) as a technological building bloc permits to develop converter operating at high frequency with reduced volume and weight. Furthermore, it is conceivable the monolithic co-integration of devices towards full-GaN switching cells. Therefore, characterization of GaN power devices is needed to provide accurate models in a wide frequency band in order to design new generations of converters. An innovative modeling method for GaN High Electron Mobility Transistor (HEMT) power transistors based on the use of Scattering parameters (S-parameters) and small-signal equivalent circuit was recently developed and validated in previous studies. Meanwhile, the demand concerning GaN diodes increases, pushing forward the need for dedicated electric model. Through S-parameters, current-voltage and current-collapse measurements, this paper presents the characterization of packaged GaN diodes with the aim to establish an accurate nonlinear model. The analyzed devices are still in the development phase, but initial results are very promising and get close to commercial SiC diodes available on the market.

The onset and pinch-off voltages shift of lateral GaN field-effect rectifier diodes (L-FER) and normally-off HEMTs are studied. It is shown that a short duration of low power SF6 plasma followed by a low temperature annealing permits to get an effective and stabilized fluorine ions deposition on the AlGaN barrier, contributing to reduce the back shift of both devices threshold voltages.

The stray capacitance of inductors impairs their high frequency impedance. A semi-analytical model is proposed for inductors with conductive core to gain insight for ways to decrease stray capacitance for high frequency power electronic applications. First the elementary capacitances are simulated thanks to 2D electrostatic finite element method (FEM), then an energetic approach is used to compute the global stray capacitance. Experimental verification has been performed on a nanocrystalline ring core. Relative error to the measurement shows that the proposed model improves the accuracy, notably by properly taking into account spaces between turns and between turns and core.

The embedded energy conversion systems onboard vehicles impose strong constraints on power density (low weight and volume) and robustness. Several solutions can be used to achieve these objectives which consist in acting either on the design of the static converter or on the electric machine. In this paper, we propose to act on the two systems together. Thus, the increase in the power density of the converter will be achieved by using wide band-gap semiconductor power devices like the SiC or GaN. These components are very small and able to operate at high frequency, thus reducing the dimensions of passive components and of the cooling system used. To increase the reliability of the electric machine, a multiphase PMSM is used. In this paper, the proposed design method of the integrated GaN inverter into a machine is presented. It will be used for the realization of an integrated GaN inverter into a multiphase PMSM.

This work proposes the electrothermal modeling of a packaged GaN power transistor in order to evaluate by simulation its performances in a 200 W – 1 MHz DC/DC converter. The complete electrical modeling of the high frequency converter using EM-circuit co-simulations is presented. After validation of the GaN transistor switchings waveforms and estimation of power losses, the operating temperature of the device is simulated and experimentally validated.

This paper presents a methodology to evaluate and analyze the volumetric power density of planar magnetics used in power electronics converters. The power density is computed for various EE and E/PLT cores considering optimal configurations for the planar transformers’ design and for its cooling heatsink. The analysis is performed for three cooling configurations: natural convection without heatsink, single sided cooled component with one heatsink, and double sided cooled with two heatsinks. This study can be very useful for designers to evaluate their design specifications and to adapt their technological choices to achieve the desired planar magnetics’ characteristics.

ElectroMagnetic Interference ( EMI) simulation of power converters helps engineers in the design process. In this paper, we describe a frequency - domain simulation method based on the Multi-Topology Equivalent Sources (MTES) model. The aim is to reproduce the non-linear behavior of power switches for a fast evaluation of the conducted EMI. The method performance is validated on a DC-DC converter.

GaN transistors allow to design highly efficient and high power density converters due to their low conduction and switching losses. However, their very fast switching and low gate threshold voltage make them prone to gate instability issues. Furthermore, they suffer from current collapse issue that is notably known to impair on-state resistance, but other effects may be expected. This paper focuses on commutation behaviour and shows how current collapse also impacts the circuit stability by altering immunity to gate oscillations. Consequently, it is shown that the conventional double-pulse test (DPT) may not provide reliable assessment of the switching cell design. Theoretical analysis is carried out and a modified DPT test bench is proposed to evaluate the influence of current collapse on GaN converter circuit stability. The analysis is validated by experimental results based on the modified DPT setup.

In order to model GaN device dynamic RDSon value due to trapped charge, a measurement circuit to accurately measure device dynamic RDSon value under different OFF-state time and ON-state time is at first proposed. Based on measurement results, an analytical model with different cells is proposed to represent dynamic RDSon evolution. It is then represented as a behavioural voltage source to compensate device ON-state VDS voltage, which can be implemented easily into device manufacturer model in Spice-type electrical circuit simulator. The model is then validated by comparing with the measurement on device dynamic RDSon value of different switching frequencies, where the model agrees with experimental results on both transient and stabilized dynamic RDSon value.

GaN power transistors are drawing extensive research interest to increase power electronics systems efficiency and power density for electrical vehicles (EV). However, GaN devices suffer from current collapse, which results in shifted device static characteristics. In this paper, different measurement methods are proposed to investigate the influence of GaN transistor current collapse on device conduction and switching losses. By proposing a measurement circuit to accurately characterise GaN transistor dynamic RDS(on) , it is shown that device dynamic RDS(on) increases to 60% bigger than its static RDS(on) value when it is operated at 1MHz converter. By proposing a modified double pulse test fixture, device switching transition can be characterised when it is unbiased. Therefore, it is shown that current collapse increases device switching losses 20% bigger than unbiased condition. It is finally represented the influence of GaN device current collapse on device safe operation area in terms of operation current and frequency in EV-based power converters.

This paper presents the feasibility of an open-loop control of Active Gate Voltage Control (AGVC) during turn-on and turn-off of GaN HEMTs in order to reduce the current or voltage switching speed. For the turn-on, two parameters (Vint, Tint) are used to reduce the current transient speed while for the turn-off three parameters (T0, Vint0, Tint0) are used to adjust the voltage transient speed. The results show that the GaN HEMT can be controlled by the AGVC. However this technique is limited by the response time of the commercial gate drivers.

Inductors are required in switching power converters for energy storage. They take a large volume compared with the other components of converters because of their small energy density. Nowadays, the operating frequency of power converters increases to MHz range because of the fast switching time of the new power GaN transistors. This allows to reduce the volume of the required inductors. In this paper, a design based on the optimization of the volume of PCB inductor for GaN converter is proposed where a flexible ferrite sheet is used to realize the inductor. The proposed method takes into account the thermal issues of the ferrite sheet. The required inductance value for the GaN converter is chosen from a Losses-Volume curve.

This paper assesses the effect of the temperature on an open loop control of Active Gate Voltage Control (AGVC) during turn-on and turn-off of GaN HEMTs in order to reduce current or voltage switching speed. For the turn-on, two parameters (Vint, Tint) are used to reduce the current transient speed while for the turn-off three parameters (T0, Vint0, Tint0) are used to adjust the voltage transient speed. Initially, the temperature effect of the parameters is assessed using the static characteristics of GaN-HEMT and then experimentally verified. The results demonstrate the degradation of the AGVC operation with the increase in temperature. This degradation is due to a variation of the transistor threshold voltage and a decrease in current capability with temperature. The temperature affects the turn-on more than the turn-off.

EMC filters consist of passive components mainly. The insertion loss and type of filter define the appropriate values of these components. However, the volume of EMI filters is usually defined by the common-mode (CM) and differential mode (DM) inductors. In order to reduce the total volume, in this paper the Coupled Common-Differential Inductor (CCDI) is proposed. In addition, two aspects are presented: the influence of the packaging and the winding strategy in the high frequency CCDI impedance. The CCDI is manufactured using two types of magnetic materials. Nanocrystalline ring core for CM impedance and iron powder for DM impedance. The experimental results highlight the advantages and disadvantages of the packaging and winding strategy of CCDI.

Wide Bandgap (WBG) power devices show very good characteristics for high frequency operation in power converters, leading to a better power integration by reducing size and weight of passive components. Access parasitics such as resistances and inductances related to packaging and interconnections are important parameters to determine in order to better predict high frequency switching of WBG power devices. In order to design a 1 MHz hybrid GaN/SiC power converter, this paper reports on the characterization of packaged power devices such as Gallium Nitride (GaN) transistors and Silicon Carbide (SiC) Schottky diodes using S-parameters in order to extract the device parasitics. The method lays on a calibration procedure carried out using specific test fixtures designed on FR4 Printed Circuit Board (PCB). The proposed method has the objective to be suitable for a wide range of power devices.

The development of the high switching frequency static converters based on Wide-Bandgap Semiconductors (GaN and SiC) equires EMI filters with high-performance for aeronautic applications. It is well known that the high frequency parasitic ouplings between passive components have a negative impact on EMI filter attenuation. In this paper, the method of eduction in parasitic couplings between component-component and component-PCB is analyzed in order to increase the EMI filter ttenuation at high frequency (beyond 10MHz). Because of simulation complexity of these high frequency couplings, the roposed method is based mainly on experimental approach. The obtained results put in evidence the effectiveness of the proposed method to improve EMI filter attenuation up to 100MHz.

— Currently, to increase the power density of static converters, it is necessary to increase the switching frequency to reduce the size of passive components. One of the solutions is to use wide-gap semiconductor components such as Silicon Carbide (SiC) or Gallium Nitride (GaN). Increasing switching frequencies causes significant voltage and current variations (dv/ dt) and (di/dt) that generate electromagnetic interference (EMI) over a wide frequency band. The subject of this paper is to study the design of an EMI filter for a DC-DC converter using a GaN transistor and SiC diode in order to reduce conducted emissions to comply with EMC standards. The EMI filter design method is based on an equivalent electrical model of the converter taking into account the impedances of the earth wire and the ground plane. A simulation based on the proposed model allowed to validate the design method by highlighting the solutions adopted to reduce noises spectrum at frequencies above 10MHz. Comparisons between the simulations results and the experimental data of conducted emissions with and without filters show the validity of the proposed method.

Power electronics converters require energy storage components. The DC-DC converters need the magnetic storage components which take a large volume. The new power GaN transistors allow to increase the operating frequency of the power converter. The consequence is a reduction of the values and the dimensions of the passive components mainly the inductors. In this paper, a design method for PCB-integrated inductors is proposed. It is based on the optimization approach of inductors volume. The inductor is integrated on PCB with a flexible ferrite sheets used as magnetic material.

Gallium Nitride (GaN) power devices developed these recent years are ideal candidates for high frequency power conversion, leading to a reduction of size, cost and weight of power converters. The design of these converters is based on simulations which require developing accurate models over a wide frequency range. This paper presents a new characterization method of GaN power transistors based on the extraction of devices small-signal parameters up to the gigahertz range using 2-port S-parameters measurements and dedicated characterization fixtures on printed circuit boards (PCB).

This paper presents a design method of a power converter that will be used to realize integrated adjustable speed drives. In order to reduce the dimensions of the static converter to integrate it to the machine, a converter based on gallium nitride (GaN) transistor is being developed. Indeed, GaN transistors packages are small and can operate at high switching frequencies which lead to the reduction of the passive component dimensions. To design this GaN-converter, the determination of parasitical elements of the gate and power circuits is necessary. In fact, these elements have a direct influence on transient behaviour, on the transistor losses and therefore on the cooling system. This work is achieved within the project CE2I (Intelligent Integrated Energy Converter).

Integrated Drives are a target in terms of simplicity in complex systems such as transportation. Anyway the integration of the power component inside the electrical machine induces challenges if the compactness is required. The CE2I project, for “Smart Integrated Drives”, searches to deal simultaneously with the constraints such as better thermal control and modelling, more efficient numerical virtual modelling for co-simulation, exploration of new materials and use of low losses, high frequency wide-band-gap (WBG) components.

The influence of the electromagnetic environment of the indoor power line grid (Houses’ Power Grid) is increasingly important on the Power Line Communication transmission. The household equipment operating changes considerably the network impedance. Several procedures exist to evaluate the network impedance. Two impedance measurement techniques seem to be the most adequate and allow to characterize loads under their operating conditions. The first one uses current injection and reception probes and the second one uses capacitive coupling. With a proper pre-measurement calibration process, the proposed methods allow to measure the evolution of the impedance versus frequency of the active loads (TV screen, Fluorescent lamp…). This study deals with the analyses of these two methods in order to evaluate their advantages and disadvantages. The measurements are carried in narrowband and broadband in the frequency range of 10 kHz to 100 MHz.

In this paper is presented the study of the influence of temperature on the attenuation of the electromagnetic interference (EMI) filters associated to the power converter used in the embedded system. It is well known that in the hybrid vehicle, the power conversion system can be located near the thermal engine where the temperature is very high. The consequence is that the performances of the passive components, like these used in the EMI filter can be affected. The aim of this paper is to study the influence of the external temperature on the electrical characteristics of the inductors and capacitors of the EMI filters used with DC-DC converter operating at 400 kHz. Firstly, each element of the filter is characterized separately to study the evolution of the different parameters with the temperature. Several capacitor technologies will be studied. Secondly, a high frequency models of the common mode (CM) and differential mode (DM) filters taking into account of the temperature influence are proposed. Finally, the filter model and the power converter impedance are used to study by simulation the influence of the temperature on the attenuation of the EMI filter. The obtained results have allowed make it possible to highlight the most influential elements on the filter attenuation.

The subject of this paper is to propose a new design method of EMI filters that allows to minimize the volume of the common-mode inductor with consideration of core saturation issues. One of the main results of this study shows the impact of the switching frequency on the filter insertion loss and the volume of the coupled common-mode inductor depending on the length of the shielded cable. Then, the relationship between switching frequency and optimum inductor volume is investigated. Obtained results show that, depending on the cable length, an optimal switching frequency that allows to minimize the inductor volume can be determined.

The ring core inductors are widely used in EMI filters to reduce the conducted emissions induced by the power converters. However, the high frequency behavior of these inductors is modified by the apparition of the stray capacitances. These elements have more influence on the efficiency of the EMI filters. In this paper, three modeling methods based on the finite elements method are proposed to calculate the stray capacitance of the core ring inductor that will be integrate in EMI filter design tool. Also, a new measurement approach of the permittivity of magnetic materials was proposed. Finally, the EMI filter model include the high frequency stray capacitances is used to calculate the insertion loss of the EMI filter in a wide frequency bandwidth.

The subject of this paper is to propose a design method of the EMI filters that allows to minimize the volume of the common mode inductor with consideration of core saturation issues. Inductor volume depends not only on its inductance value, but also on the relationship between the filter and its environment which can saturate the magnetic material due to many parameters, especially when the filter resonance frequency Fr is higher than the converter switching frequency Fs. One of these parameters is the converter duty cycle D. This study explains why it is more desirable to set Fr below Fs in order to reduce the coupled inductor volume while increasing the filter performances.

EMI filters are necessary in many applications in order to meet EMC standards, which significantly increase overall cost and volume mainly because of the common-mode choke. In this paper, a new method to calculate the minimum volume of the inductor is proposed. It takes into account core saturation issues that may greatly impact inductor volume. Consequently, it is shown that in some cases, increasing the inductance up to an optimal value can significantly reduce the filter volume in addition to further enhancing filter attenuation. Besides, determination of the filter resonance frequency with nano-crystalline material is worked out to support the analysis.

It is well known that static converters are sources of conducted and radiated emissions. To reduce the conducted emissions towards the power network and meet with electromagnetic compatibility (EMC) standards (EN 55011), several solutions can be applied. The most used solution consists to install electromagnetic interferences (EMI) filter at the input side of the power converter. This paper deals with an EMI filter design method using the simulations at the design stage of the energy conversion system. In order to carry out these simulations, the accurate models based on high frequency equivalent electrical circuits are necessary. The aim of this study is to identify the different values of the filter models but also to obtain the limits values of the high frequency stray elements of the passive components which have a more important influence on the efficiency of the filters. One will also study the influence of the ground plane impedance on the performances of the filter in high frequency band. To valid the proposed method, the simulation results are compared to the measurements data without and with the EMI filter.

In this paper, the thermal resistance of planar magnetic components in natural convection is studied in order to obtain analytical formula taking into account effects of ambient temperature as well as power dissipated inside the component. The analytical model is deduced from Computational Fluid Dynamic simulations and is validated with measurements on prototypes.

This paper focuses on pulse-width modulation (PWM) strategies that aim at cancelling common-mode (CM) voltage generated by power converters. In the typical use case of frequency converters, such strategies perform simultaneous switching between different inverter legs, so that their effects on CM voltage cancel each other. Doing so, the resulting CM voltage is reduced to mere commutation residues because simultaneous switching voltage waveforms may not be identical nor perfectly synchronous. Based on a PWM strategy that theoretically cancels the CM voltage generated by a variable-speed drive, this paper highlights the influence of desynchronization effects, commutation speeds, and different waveforms due to instantaneous currents, on the resulting CM voltage spectrum. Practical rules are derived in order to optimize the electromagnetic compatibility (EMC) performance of such PWM strategies.

Since some years, one solution to increase the power density of the power converters consists to use the wide band gap semiconductors like SiC and GaN. These devices allow having power converters that operating with the high switching frequencies. These fast devices induce of very high variations of the voltage (dv/dt) and current (di/dt) during commutations. The direct consequence is the generation of the very high levels of the electromagnetic interferences (EMI) in a wide frequency band. This study is focus only on the conducted emissions induced by a Buck converter using GaN-transistor and SiC-diode. To reduce these emissions and to comply with EMC standards, one solution consists to use an EMI filter. In order to design the EMI filters by simulations, a modeling method based on an electrical equivalent circuit is proposed. This method allows taking into account of additional common mode impedance that correspond to the ground plane often neglected in the design of the filters. The comparison of the simulation results and measurements of the conducted emissions of the Buck-converter without and with the EMI filter confirm the validity of the proposed approach.

Ring core inductors (RCI) are widely used as filter components for electromagnetic interferences (EMI) mitigation. In order to design these filters with accuracy, a behavioral model of the RCI, based on an equivalent electrical circuit, is proposed. This model takes into account the frequency-dependent impedance of ferrite and nanocrystalline RCI. The main contribution in this model is the inclusion of the capacitive behavior (dielectric behavior) of the ferrite material, the skin effect in the nanocrystalline material and the parameterization of the electrical equivalent model by the number of turns of the coil. The proposed Behavioral Ring Core Inductor (BRCI) model is simulated and verified with experimental measurements

Usually, the insertion loss (IL) of the EMI filter is characterized under 50Ω/50Ω input and output impedances even if these impedances are different in the real application. In this paper, two approaches are presented to calculate the insertion loss of the filter taking into account the arbitrary input and output impedances. First, a black-box 50Ω/50Ω model is obtained from S-parameters and then extended to determine the IL of the EMI filter with different impedances. And second, a direct measurement procedure interconnecting the real impedances obtained with the measurement equipment. Both approaches are compared to the real insertion loss calculated from conducted emissions with and without filter

This paper presents a PWM strategy for the reduction of common-mode (CM) voltage generated by variable-speed motor drives composed of two-level, three-phase active-front-end rectifier and three-phase inverter. This method theoretically provides complete elimination of the CM voltage by synchronizing all inverter commutations with rectifier commutations, so that the resulting CM voltage does not vary. The degrees of freedom of this strategy are studied and an experimental implementation is provided on a 15 kW prototype to validate the method effectiveness. Taking into account dead-time compensation, measurements in time and frequency domains show that the CM voltage is strongly reduced and that more than 15 dB reduction is achieved in a wide frequency range.

This paper deals the design of EMI filter associated with DC-DC converter using fast semiconductors as a silicon carbide SiC (diode and transistor JFET). The converter used in our study is a buck converter 200V, 2A operating at a switching frequency of 200kHz. To comply with EMC standards, a filter design method based on an electrical equivalent circuit model is proposed. Values of the various elements of the filter are obtained by simulation. The improvement provided by our model is important mainly in HF (above 1MHz) taking into account the impedances of the different propagation paths of the common mode currents of the converter. The comparison of the simulation results with the measurements data carried out on a converter without and with the EMI filter, shows the effectiveness of the proposed design approach.

In the simulation of power electronics systems, for reasons of computing time and convergence, it may be necessary to use ideal components which generate ideal voltage switchings (steep edges). However, in reality, these voltage variations are far from ideal and to reproduce a voltage closer to reality, it is necessary to model these variations. This is especially important for the study of residual voltage obtained by simultaneous switching, which are present in PWM strategies developped to reduce the impact of the common-mode voltage generated by 3-phase inverters. This paper is focused on the required model accuracy, in order to take into account these residues obtained by the synchronization of switching voltages.

The classic procedure design of EMI filters determines the insertion loss of the common mode and differential mode filters under standardized 50Ω at the input and output impedances. In order to choose the more adapted filter topology for a static converter, it’s necessary to consider the exact impedances connected to the input and output port in operating conditions. These impedances represent the LISN and the static converter which are measured with the current injection method. For simulation purpose, equivalent electrical circuit models are obtained and then applied in the filter design process.

With the advantage of high bandwidth and small insertion impedance, a current surface probe (CSP) used to measure switching current waveforms is presented in this paper. Its transfer impedance is characterized and validated in the first time by measuring an IGBT switching current with a passive current probe (CP) and a Hall effect current probe (HECP). It is also shown that a return current beneath the PCB on which is put the CSP can reduce its transfer impedance. In the second time, the CSP is used to measure a GaN-HEMT switching current and the obtained results are compared with those measured with a current shunt (CS). The comparison of these results prove that CSP and CS are able to measure fast switching current (of the order a few nanoseconds). However, the advantage of the CSP is that it has no influence on the power device VDS voltage measurement. Also, the CSP brings less parasitic inductance in the commutation mesh than the CS and it does not have the ground connection drawback, which is the case for the CS.

The paper focuses on the design of EMI filter for a power converter used Silicon Carbide power devices (SiC-JFET and SiC diode). The DC-DC converter used in this study is a buck converter which has operating frequency of 100 kHz and the turn-on and turn-off times of the JFET are equal to ten nanoseconds. It is well known that the switching times have a direct link to the spectrum of the EMI sources. In order to reduce the conducted emissions induced by the SiC-converter, it’s necessary to add an EMI filter in order to compliance the EMC standard. In this paper, design method of the EMI filter based on the simulation is proposed. For this, a high frequency model of the filter which takes into account of all impedance paths of the system is used. Values of the various elements of this model are determined by a new approach. The improvement provided by this model is important in high frequencies (above 1 MHz) taking into account the measured impedances of different propagation paths of the common mode currents of the system. The conducted emissions measured without and with the obtained EMI filter show the effectiveness of the proposed design method.

In recent years, design and service evolution in electric distribution networks are mainly guided by the increasing in the customer consumption and the emergence of new sources and loads such as renewable energy, electric and hybrids vehicles. The lack of control over these new constraints in the future may lead to technical and financial problems. Therefore, establishing a supervisory strategy offering a more advanced knowledge of distribution networks is an interesting alternative compared to an expensive strengthening of current networks. Power Line Communication (PLC) technologies present a significant advantage for a supervision application of electric distribution networks. Nevertheless, these networks have not been developed to transmit High Frequency (HF) signals like a PLC. Thus, they induce difficult propagation conditions for PLC. This paper presents an approach to model in HF one element of the distribution network: the MV/LV transformers which established the connection between Medium Voltage (MV) and Low Voltage (LV). The proposed modeling method is based on a black box model whose parameters are obtained from various impedance measurements. It has been applied to four transformers most commonly used by Gérédis, French Distribution System Operator (DSO).

The electrical power aboard aircraft tends to increase thanks to the progress in switched-mode power converters. The generalization of the use of power converters leads to EMI issues. The EMC standards compliance is often obtained by adding an EMI filter after a measurement on a prototype. Since prototyping is costly and time consuming, it is interesting to evaluate the level of EMI without prototyping. To achieve this goal, frequency-domain simulation is interesting, but classical method can not give a good representation of non-linear transition of the power switches. That is why a new frequency domain method is proposed. This method uses two equivalent generators topologies and combine them to obtain an accurate results. The combination is based on the use of validity functions associated with each topology. This paper is focused on the impact of the validity functions on the final result.

Two current probes, based on the current injection method, are designed with appropriated high frequency magnetic material. These probes are used to measure the common-mode impedance of power converters in real-operating conditions. The characterization of this impedance is of importance for the EMI filter design. In this paper, a simple formulation of the probe’s transfer impedance using S-parameters is proposed. The proposed probe allows improving the accuracy of the impedance measurement in a wide frequency band up to 100 MHz. Different measurements of common-mode configurations are detailed and discussed.

The characterization of voltage-dependent capacitances of power semiconductor devices is very important for modeling their dynamic performances. A measurement method using multiple current probes has been proposed to characterize inter-electrode capacitances of power devices. The advantage of this method is that it can isolate the measurement devices from the high-voltage DC bias power source. This method has been validated first on SiC JFET to obtain more capacitance dependency information both on high voltage of Vds and on Vgs , of which the latter is not included in datasheet. It is then applied on GaN HEMT, to prove its sensibility for a few picofarads capacitances measurement.

This paper presents a method to improve EMI filters performances, based on the optimization of the component layout. It’s well known that the EMI filter insertion losses are highly degraded by the high frequency stray couplings between filter passive components. The latter can be reduced by acting on these components’ placement. This paper proposes a method that allow to determine the components’ positions for minimizing the parasitic coupling between them. Their placement is deduced from the study of current distributions and magnetic field induced by these components. This method examines more specifically the parasitic inductive couplings between inductors and capacitors. The choice of the placement that minimizes couplings in 3D is determined to achieve better performance. Some prototypes are realized ​​and characterized to validate the proposed method.

EMI filters are essential parts in power converters to reduce the conducted EMI emissions in order to meet with EMC standards. However, the parasitic capacitances of Common Mode (CM) inductors of filters limit their performances on high frequencies. This paper proposes a complete procedure for modeling the parasitic capacitances of CM inductors in planar technology. The proposed method uses analytical multilayered Green function to determine the capacitance matrix in 2D configuration. Then an energetic approach is applied for calculating the equivalent parasitic capacitances. The proposed procedure is validated by measurements on several prototypes. The calculated results show good agreement with the measured ones.

Since the early 1990’s, electrical energy tends to replace pneumatic and hydraulic energy aboard aircrafts. This is lead by MEA project and allows to reduce weight and volume of the actuators. But an increase of onboard electric energy leads to EMI issues. To comply with EMC standards, an EMI filter is often added to the electrical systems. In order to reduce the weight and volume impact of EMI filters, it is interesting to perform an optimization of the embedded electrical system at the design stage, based on EMC criteria, using a simulation approach. In order to perform these simulations, HF model of the system is necessary. Two approaches exist: either time-domain or frequency-domain simulations, each one having advantages and drawbacks. This paper presents a frequency-domain modeling method. The proposed method is based on the use of two linear equivalent noise generators topologies. The results obtained with the two topologies are combined, to obtain a good representation of power converters. This method increase the validity range of the simulation above 30MHz.

The increase of electric energy in aircraft leads to EMI issues, because the use of power electronics converters induces sharp voltage and current variations. EMC standards compliance often calls for EMI filtering. In order to simulate a system up to 50MHz it is necessary to use high frequency models of the studied system. The subject is to perform a frequency-domain analysis which induces short simulation times but cannot represent non-linear phenomena. In this paper, we propose EMI noise source models with topology combination through convolution of appropriate ”validity functions” to overcome this drawback. Comparison with time-domain simulations shows the validity of the proposed approach in a wide frequency range.

The passive magnetic ferrite components used in EMI filters have a complex magnetic permeability (CMP) which varies with frequency. The CMP in frequency range from 150 kHz to 30MHz is not given by manufactures. Moreover, measurement techniques require some specific size and shape of sample to measure CMP of ferrites. Common application of these passives components are EMI filters, where toroid ferrite cores need to be characterized to determine the insertion loss function. In this paper a CMP measure procedure is proposed. The leakage inductance and parasitic capacitance of an inductor are determined. Then, a rational function approximation (RTA) is applied to represent the HF equivalent impedance of CMP.

Power semiconductor components with high switching speed are widely used in static converters. However, they pro-duce conducted electromagnetic interferences in high frequencies. Filters are one solution for reducing the conducted emissions. However, the parasitic elements of the passive components in the EMI filter deteriorate its performances. In this paper, we propose to study a differential mode (DM) inductor in planar technology. The goal is to reduce the parasitic capacitance of the planar DM inductor via an improved parasitic capacitance cancellation technique. The technique is based on the results of an analytical method using Electric Field Decomposition and energy based approach. The cancellation is then realized through the structural parasitic capacitances under an optimal geometry configuration. The efficiency of the proposed cancellation technique is validated by measurements.

The aim of this paper is to propose a new design method of EMI filters for the power converters using high frequency models of the passive components. It is well known that the static converters are the main source of conducted disturbances of the common mode and differential mode. Often, the solution used to reduce conducted emissions consists to use the EMI filters. The design of these filters is very difficult because it requires complete mastery of the design process. In this paper, a high frequency modeling method of the coupled inductors of filter is proposed. Coupled inductors and capacitor models are used to make a complete EMI filters. The high frequency models of these components are used in the simulations and the obtained results are compared to a prototype measurement data. A new EMI filters design method based on the optimization of the stray elements is detailed. It is based on the analysis of conducted EMI induce by the DC-DC converter.

Impedance measurements are widely used to characterize the behavior of n-windings magnetic components. The identification process is realized manually and becomes more and more difficult as the number of equivalent circuit parameters increases. This paper deals with an automatic identification method based on Rational Function Approximation (RFA) which enables to obtain these parameter values very quickly and leads to reliable models. The effectiveness of such method is demonstrated with the characterization of a planar common mode inductor and a toroidal coupled inductor.

This paper deals with an experimental process offering a quasi instantaneous visualisation of the Electric or magnetic fields distribution. This experimental process is based on an antenna connected to electro-optic sensor which converts the field received by the antenna in light. Colour light varies with the level of the field. By moving quickly the antenna in a plan, a camera configured long pause, records any light information gathered during the movement of the antenna. Then this device offers a visualization of the field distribution in a plane in color scale. This paper is focused on the assessment of this experimental process, by comparison of the distributions of field obtained using this setup with the simulation results. This study is carried out at 10 MHz and is based on the magnetic field.

Cet article traite du dimensionnement des filtres CEM utilisés pour les convertisseurs DC-DC. Les convertisseurs statiques utilisés dans les systèmes de conversion d’énergie génèrent d’importantes perturbations conduites de mode commun et de mode différentiel. Pour réduire ces perturbations et respecter ainsi les normes CEM en vigueur, il est nécessaire d’utiliser des filtres CEM. L’objectif de cet article est de proposer une méthode de dimensionnement des filtres CEM basée sur des mesures et des simulations. Les résultats de simulation du filtre proposé sont comparés aux résultats expérimentaux obtenus en utilisant un dispositif de mesure spécifique. Les résultats obtenus montrent une bonne concordance entre les courbes simulées et les relevés expérimentaux pour des fréquences variant de 150 kHz à 30 MHz.

Abstract -- This paper deals with conducted electromagnetic interferences (EMI) generated by the power static converter used in the adjustable speed drive (ASD) applications. To study, by simulation, the conducted emissions induced by the power converter with reasonable calculation duration, a simple high frequency model of noise sources is necessary. In this paper, EMI sources of the PWM inverter are modeled using an equivalent current or voltage generators in the time domain. The simulation results are compared with measurement data in the frequency domain. In order to validate the proposed model in the ASD system, it is necessary to use a precise model of energy cable and AC motor which take into account various phenomena which appear when the frequency increases. A model of the shielded 4-wire energy cable that taking into account of the dissymmetry structure is used. The obtained high frequency ASD model is used to estimate the conducted emissions over all inverter functioning period.

The subject of this paper is the design of EMI filters for the DC-DC converters. It is well known that the static converters used in electric traction systems are major sources of conducted disturbances which are the common mode and differential mode. Often, the solution used to reduce conducted emissions consists to use the EMI filters. The design of these filters is very difficult because it requires complete mastery of the design process. In this paper, we propose a design method of the EMI filter based on the simulation of the filter in frequency domain. Thus, the high frequency models of the filter components are proposed. The obtained models have been tested and give good results on a large frequency range, from 9 kHz to 30 MHz.

This paper analyzes the electrical parameters of differential-mode (DM) and common-mode (CM) inductors used in EMI filters. To design an EMI filter, it is necessary to identify the various parameters of the passive elements: inductors and capacitors. Because of their major impact on filter efficiency, these elements must be identified with accuracy. In this study, a high frequency model of coupled inductors is proposed. Simulation results of the proposed model are compared to the experimental data obtained using a specific experimental setup. These results made it possible to validate the filter model in frequency range varying from 9 kHz to 30 MHz. The proposed high frequency coupled inductors model will be very helpful for EMI filter optimization design.

This paper deals with a high frequency modeling method of the common and differential mode inductors used in EMI filters. These filters are intended to reduce conducted emissions generated by power static converters towards power network. To model the EMI filters, it is necessary to identify the various parameters of the passive elements: inductors and capacitors. Because of their major impact on filter efficiency, these elements must be identified with accuracy. In this study, high frequency model of common mode coupled inductors is proposed. Simulation results of the proposed model are compared to the experimental data obtained using the specific experimental setup. These results made it possible to validate the proposed filter model and its robustness in a frequency range varying from 9 kHz to 30 MHz. The proposed high frequency inductor models will be very helpful for design optimization of EMI filters, since the high frequency behaviour of the filter mainly depends on magnetic materials used and on the geometrical characteristics of winding.

The paper presents the first step of an EMC Electromagnetic Compatibility) analysis of a railway power substation in high frequency with reduced scale model. The mock-up of the substation is powered by a 220 V three-phase voltage supplied by a 15 kVA power transformer, a rectifier and loads. The study consists in designing an equivalent electrical circuit of power transformer in high frequency, available over a large panel of loads. The model of power transformer was deduced from measurements in frequency domain within the range 40 Hz to 30 MHz.

The utilization of the simulation tools to predict Electromagnetic Interferences (EMI) of the power converters is a necessary step in the conception of the system. This paper describes the high frequency behavior modeling method of an Adjustable Speed Drive (ASD) that will be used to estimate the conducted emissions. In order to study the influence of various elements of the ASD on the EMI level, it is necessary to use a precise model of the PWM inverter, energy cable and AC motor, which take into account various phenomena that appear when the frequency increases. In this study only the common mode emissions are considered. To model the PWM inverter, three equivalent common mode noise sources corresponding to inverter switches are used and that will be modeled using a trapezoidal voltage generator using average values of the rise and fall times over a PWM inverter period. The high frequency current that appears in the system is essentially caused by common mode capacitances between the energy cable + motor and ground. A model of the cable has been proposed and validated in the frequency domain for two different lengths. The obtained high frequency ASD model is used to estimate the conducted emissions on all inverter functioning period. In this study SPICE is used to simulate the system in the time domain. The comparison of measured and simulation results of conducted emissions (with LISN) shows a good concordance. One can conclude that the proposed ASD behaviour model gives results with an acceptable precision and with reasonable simulation duration.

The utilization of the simulation tools to predict Electromagnetic Interferences (EMI) of the power converters is a necessary step in the conception of the system. This paper describes the high frequency behavior modeling method of an Adjustable Speed Drive (ASD) that will be used to estimate the conducted emissions. In this study only the common mode emissions are considered. To model the PWM inverter, three equivalent common mode noise sources corresponding to inverter switches are used and will be modeled using a trapezoidal voltage generator using average values of the rise and fall times over a PWM inverter period.

Understanding and characterizing complex EMI phenomena through accurate converters EMI noise emission models is a necessary first step for achieving an efficient filtering. Some of the existing EMI noise source models are only valid for specific applications. In order to study, by simulation the conducted emissions in PWM inverters with reasonable calculation duration, a behavioural model of EMI noise is necessary. In this paper, two EMI noise source models are proposed. It is used to represent the commutation transients of a power device via an equivalent current or voltage source.

Pulse-width-modulated (PWM) voltage-source inverters are known to provoke high-frequency disturbances in motor-drive applications, especially when long cables are used. Indeed, the parasitic elements of the cable along with steep voltage transitions due to semiconductor switchings are responsible for conducted electromagnetic emissions as well as high overvoltages on the motor terminals. Therefore, several specific PWM schemes have been proposed in order to reduce these phenomena without requiring large passive filters. However, strategies which reduce common-mode currents (main conducted electromagnetic emission) tend to increase the overvoltages generated on the motor. This paper focuses on a new PWM strategy which reduces the common-mode currents generated by three-level inverters. It provides a control algorithm which makes sure that the motor overvoltages never exceed those of conventional strategies, while improving the electromagnetic-compatibility performance of the drive

In adjustable speed drive applications, the switching of the inverter semiconductors generates common mode currents as well as harmful overvoltages on the motor terminals when long cables are used. Consequently, bulky and expensive input and output filters must be used. This work aims at reducing these disturbances from their origin by using a three-level neutral-point-clamped (NPC) inverter controlled with a new pulse-width-modulation (PWM) strategy. Whereas previous common mode noise-reducing strategies usually generate higher overvoltages than conventional ones, the proposed PWM is able to manage both problems thanks to its internal degrees of freedom.

Active Gate Voltage Control (AGVC) consists in introducing an intermediate voltage level into the control voltage of isolated gate transistors at turn-on: it allows to force the rate-of-rise of current through the switched-on device to a fixed value [1]. In the case of AC-AC converter (alternative chopper), it is then possible to set the amplitude and duration of this intermediate voltage level so that each device switching may be achieved under reduced overcurrent and overvoltage conditions, simultaneously. In this paper, switching operation analysis and experimental results are presented, for antiseries association of diodes and IGBTs (series-connected current bidirectional switches). A closed-loop active gate voltage control is applied to control short-circuit current into the 2 bidirectional switch cell. Such a complete and safe control allows to avoid overvoltage across switching devices.

The rapid commutation of the modern power semi-conductor devices used in the static converters is the source of the conducted and radiated emissions. These devices produce high voltage variations (dv/dt) which excite leakage elements of the power circuit and induce high frequency parasitical currents. These currents used the energy cables to be propagated from the converter to the load and the power grid. This paper proposes a high frequency modelling method of energy cable that takes into account phenomena that appear when the switching frequency increase as: skin and proximity effects and dielectric losses. The proposed method is applied to the three-wire unshielded cable and extended to the four-wire shielded cable. The obtained models are validated in both frequency and time domain in Adjustable Speed Drives system.

The rapid commutation of the modern power semi-conductor devices used in the static converters is the source of the conducted and radiated emissions. These devices produce high voltage variations (dv/dt) which excite leakage elements of the power circuit and induce high frequency parasitical currents. These currents used the energy cables to be propagated from the converter to the load and the power grid. This paper proposes a high frequency modelling method of energy cable that takes into account phenomena that appear when the switching frequency increase as: skin and proximity effects and dielectric losses. The proposed method is applied to the three-wire unshielded cable and extended to the four-wire shielded cable. The obtained models are validated in both frequency and time domain in Adjustable Speed Drives system.

A new carrier-based PWM for the reduction of common mode currents applied to Neutral Point Clamped inverters

Inverters used in adjustable speed drives create common mode voltages with high dv/dt transitions resulting in high frequency common mode currents which flow to the ground through stray capacitances. These common mode currents are known to damage the bearings of electric machines and cause malfunctions in other surrounding electronic devices, and therefore need to be confined by using bulky and expensive electromagnetic compatibility (EMC) filters . The presented work focuses on the three levels neutral-point-clamped (NPC) inverter and proposes a new pulse width modulation (PWM) strategy for the reduction of common mode currents by lowering the number of step variations of the common mode voltage. Unlike previous strategies, this carrier-based PWM pays attention to the real phenomena involved in the generation of common mode currents so as to efficiently reduce them by avoiding dead time effects . The new strategy has been implemented in a 20 kVA prototype and the experimental results presented in this paper confirm its best EMC behavior compared with classical PWM.

The use of high frequency switching power devices in the Adjustable Speed Drives (ASDs) induces high voltage variations (dv/dt) that result in exciting parasitic elements into the power circuit, leading to conducted emissions at high frequencies. Thus the advent of these devices has generated several unexpected problems, such as premature deterioration of motor ball bearings and high increases the ElectroMagnetic Interference (EMI) levels, caused by circulation of the high frequency parasitic currents. This paper deals with high frequency modeling of the ASD system that will be used to study the influence of the PWM inverter commutations on level of the common mode and the differential mode currents between power converter and motor. First a shielded 4-wire energy cable model is presented. Next, the high frequency models of the PWM inverter and AC motor models are proposed. Finally, the ASD system is simulated and the obtained results are compared to the experimental measurements.

In Adjustable Speed Drive (ASD) applications, most cables connecting the electronic voltage source to the ac-motor are multi-wire and shielded. The various inductive and capacitive effects are at the origin of high frequency phenomena that require models with distributed parameters as in transmission lines. From curves showing the evolution of the cable impedance with frequency, and under the assumption of choosing appropriate models, it is possible to calculate the values of the numerous parameters of the model from design tool software. This paper deals with the modelling of a shielded 4-wire energy cable, with the determination of the values of the parameters R, L, C and G of the energy cable, in order to obtain an equivalent electric model which is valid both in the time and frequency domains. The obtained results show that the proposed model reproduces the oscillations of current induced by the hard switchings of the power converter with a difference lower than 10% when compared to experimental measurements.

In adjustable speed drive applications operating at high switching frequencies, common mode and differential mode perturbations may cause premature ageing of electric machines and important electromagnetic radiations. These disturbances are generated by the power electronic converter, but can be amplified by the connection between the converter and the electric machine. This connection is ensured by multi-wire energy cables, shielded or unshielded. If it is easy to find models allowing to simulate the High Frequency behavior of cables intended to transmit information, the HF models of the cables intended to carry electric power are still to be built. This article deals with HF modeling of an unshielded 2-wire energy cable. A model with distributed constants is proposed and validated in both time and frequency domains, first in voltage pulse mode and loaded by a pure resistive load, then in an experimental setup where the cable ensures the connection between an elementary power electronic converter and a load with inductive couplings and stray capacitors.

Dans un variateur de vitesse utilisant un convertisseur électronique de puissance, les commutations des interrupteurs sont à l’origine de perturbations à la fois conduites et rayonnées. Les perturbations conduites empruntent 2 chemins correspondant respectivement au mode différentiel et au mode commun. Pour réduire ces perturbations, il est utile de déterminer les impédances des différents tronçons constituant les chemins de propagation identifiés. Les mesures effectuées dans les domaines temporel et fréquentiel permettent d’abord de valider le schéma équivalent proposé pour ces chemins. La prise en compte de l’état ON ou OFF des diodes du redresseur d’entrée montre ensuite la nécessité d’avoir recours à 2 schémas équivalents légèrement différents.

The use of high frequency switching power devices in PWM inverter induces high voltage variations (dv/dt) that result in exciting parasitic elements into the power circuit, leading to conducted and radiated emissions at high frequencies. Thus the advent of these devices has generated several unexpected problems, such as premature deterioration of ball bearings and high levels of electromagnetic emissions, caused by circulation of parasitic currents. The conducted emissions are propagated in Common Mode (CM) and Differential Mode (DM). The disturbing behaviour of the inverter can be reduced to 2 commutations modes: commutation from diode to transistor associated with diode reverse recovery, and commutation from transistor to diode where highest dv/dt may occur. In this paper, the repartition of conducted emissions into CM and DM currents is analysed, showing that both propagation modes may interfere.

To day, Adjustable Speed Drives (ASDs) uses high-speed switching devices such as the Insulated Gate Bipolar Transistors (IGBTs) to achieve higher efficiency, low weight and small size. The fast power devices transition has generated high levels of electromagnetic emissions, caused by flowing of parasitic capacitive currents. In order to evaluate these currents, a high frequency PWM inverter drive model is proposed by the identification of the spreading paths. In this paper, first the simulations are carried out using the proposed high frequency model and compared with experimental results. In the second part, a CM choke and reduction of the dv/dt by varying a gate resistance of IGBTs are used allowing to minimize de conducted emission in the ASD.

Introducing intermediate levels into the gate control voltage of isolated gate transistors allows to slow down current or voltage rising into the switching device, thus reducing overcurrent due to reverse recovery of the associated diode, and resulting in ElectroMagnetic Interferences. But the same reduction may be achieved simply by increasing the gate resistance value into the control circuit. In this paper, it is shown that slowing down the current or voltage rate-of-rise by intermediate voltage level leads to better performances in terms of delay times and switching losses than higher gate resistance value.

Permanent progress of insulated gate transistor technologies (like MOSFET and IGBT) increased their utilization in the power converters functioning at higher frequencies. The utilization of this switch induces rapid variations of the current (di/dt) and voltage (dv/dt) produced conducted and radiated emissions in wide frequency bands. To reduce these perturbations as well as those linked by the control electronics, there exist various solutions. We propose here an approach associating two EMI reduction methods. A direct method that allows to reduce perturbations to the source by acting directly on the gate control voltage of the power switches, and a passive filtering method allowing to reduce conducted emissions up to 30MHz. The advantages of the association of these two methods are to allow an optimization of the passive filtering installed. The waited benefit is a cost and weight of the converter what is a mainly advantage for the embarked equipment. In this study, the proposed method is applied to 6 kW converter.

In the last years, Adjustable Speed Drives (ASDs) manufacturer’s uses Insulated Gate Bipolar Transistors (IGBTs) as the power switching devices. However, the advent of fast power devices has generated several unexpected problems, such as premature deterioration of ball bearing and high levels of electromagnetic emissions, caused by flowing of parasitic capacitive currents known as common mode (CM) currents. In order to reduce these currents, a suitable modeling of an AC motor is obtained by the identification of the spreading paths. By connecting the model of the cable with a proper high frequency model of the motor and the equivalent model of the converter, a representation of the whole ADS is developed. In this paper, first the simulations are carried out using the proposed model and compared with experimental results. In the last part, a CM choke method is used allowing to reduce de CM current in the ASD.

Introducing an intermediate voltage level into the control voltage of isolated gate transistors at turn-on allows to force the rate-of-rise of current through the switched on device to a fixed value. In the case of AC-AC converter (alternative chopper), it is then possible to set the amplitude and duration of this intermediate voltage level to a unique fixed value so that each device switching may be achieved under reduced overcurrent and overvoltage conditions, simultaneously. In this paper, switching operation analysis and experimental results are presented, for antiseries and antiparallel-associations of diodes and transistors, MOSFET or IGBT. This switching circuit is applied to control short-circuit current into an AC-AC commutation cell. Such a complete and safe control allows to avoid overvoltage across switching devices.

As a consequence of rapid spread of power semi-conductors and power electronic systems, interference levels on power mains have increased significantly in intensity and frequency of occurrence. Most power semiconductors produce conducted and radiated disturbances. To reduce this ElectroMagnetic Interferences (EMI), a new simple control technique for isolated gate transistors is presented which allows to act upon turn-on and turn-off transition waveforms just as an integrated adjustable snubber may do. This control may be applied to MOSFET or IGBT and allows to reduce the di/dt and dv/dt during commutations. In a simple elementary commutation cell such as a buck converter, it allows sensible reduction of overcurrent and oscillations associated to diode reverse recovery.

Nous présentons les résultats d’un travail qui a consisté à réaliser l’étude pratique et à simuler le comportement d’une cellule de commutation à Interrupteurs Bidirectionnels en Tension et en Courant (IBTC). Ce type d’interrupteur n’étant pas disponible sous une forme monolithique, il faut le réaliser en effectuant l’association de plusieurs composants élémentaires. Afin de simplifier l’étude, nous distinguons deux types de cellules de commutation suivant qu’elles utilisent des interrupteurs unidirectionnels ou bidirectionnels en tension. Une étude préalable de la cellule à interrupteurs trois segments bidirectionnels en tension permet une bonne analyse des phénomènes capacitifs et ainsi de faciliter la description du comportement de la cellule à IBTC (quatre segments).

Today the insulated gate semiconductor (MOS, IGBT and MCT) is one of the most important power devices for mediums power inverter applications. Parallel to the continued development of the new generation of the IGBT somme other insulated gate semiconductor are also under development for example the MCT. The MCT (Mos Controlled Thyristor) is the new component who to be an alternative to IGBT in medium and high power applications. The primary aims of this study is to make a comparison between this two component in Zero-Current-Switching mode (ZCS). The test circuit are choice, allowing the above switching conditions single shot mode and with adjustment of differents parametres of turn-off transition in ZCS mode. The experimental results are presented for this two insulated gate devices, operating in ZCS switching mode in a constant frequency controlled buck converter.

A new simple control technique of isolated gate transistors is presented which allows to act upon turn-on transition waveforms just as an integrated adjustable snubber. This control may be applied to MOSFET or IGBT. In a simple elementary commutation cell such as a buck converter, it allows sensible reduction of overcurrent and oscillations associated to diode reverse recovery. It is also possible to eliminate dead times between gate driving pulses into an inverter leg. In applications such as ac-ac direct converters, where bidirectional switches are necessary, safe operation of commutations is somewhat hard to obtain and the new control technique may be of great help

Insulated gate semiconductor switches are easy to drive, and as their voltage and current ratings rise, they allow for better performances of static power converters. But apart from the MOS that is an unipolar device, it is still hard to reach high operating frequencies without the associated commutation losses becoming excessive. One among the possible solutions is to get the switches embedded into such a circuit as turn-on switching occurs at zero voltage, or turn-off switching occurs at zero current, then providing favorable conditions for soft-commutation. Zero-voltage-switching (ZVS) or Zero-current-switching (ZCS) may be driven by the alternative source or sink of the converter, or by an oscillating circuit connected close to the switch which then becomes a resonant switch; converters using such resonant switches are called quasi-resonant converters (QRC). In this paper, experimental results are presented for two insulated gate devices, IGBT and MCT respectively, operating in zero-current switching mode, in a constant frequency controlled buck converter.

A numerical model of GTO thyristor used in a zero-current-switching (ZCS) configuration is presented. It behaves as a quasi-resonant switch and application to a buck chopper circuit is described. In such a circuit, the GTO thyristor and the free-wheeling diode undergo and/or generate various types of stresses which cannot appear if the switches are modelled as two-state resistors (Ron and Roff), as is the case with many power circuit simulation softwares. Much more precise models have been developed from semiconductor physics, but they hardly apply to power circuit simulation because of the associated large number of equations. The purpose of this paper is to present a simple model of GTO thyristor derived from the device physics and allowing to represent the behaviour at turn-off in ZCS configuration. This was achieved with the use of Bond-Graph technique.

A numerical model of GTO thyristor used in a zero-current-switching (ZCS) configuration is presented. It behaves as a quasi-resonant switch and application to a buck chopper circuit is described. In such a circuit, the GTO thyristor and the free-wheeling diode undergo and/or generate various types of stresses which cannot appear if the switches are modelled as two-state resistors (Ron and Roff), as is the case with many power circuit simulation softwares. The purpose of this paper is to present a simple model of GTO thyristor derived from the device physics and allowing to represent the behaviour at turn-off in ZCS configuration. This was achieved with the use of Bond-Graph technique. The GTO model appears to be in good concordance with experimental results, and it may be used to show how ZCS GTO turn-off losses depend on time-shift between GTO and auxiliary thyristor gating signals, respectively.

This paper reports on a new numerical model of GTO thyristor embedded in a buck converter configuration. In such a circuit, the GTO thyristor and the free-wheeling diode undergo and/or generate various types of stresses which cannot appear if the switches are modelled as two-state resistors (Ron and Roff), as is the case with many power circuit simulation softwares. Much more precise models have been developed from semiconductor physics, but they hardly apply to power circuit simulation because of the associated large number of equations. The purpose of this paper is to present a simple model of GTO thyristor derived from the device physics and allowing to represent the behaviour at turn-off in ZCS configuration. This was achieved with the use of Bond-Graph technique. The GTO model appears to be in good concordance with experimental results, and it may be used to show how ZCS GTO turn-off losses depend on time-shift between GTO and auxiliary thyristor gating signals, respectively.

Les convertisseurs d’électronique de puissance génèrent des perturbations électromagnétiques conduites dans une large bande de fréquences. Afin d’éviter de polluer le réseau électrique et respecter ainsi les normes de compatibilité électromagnétique (CEM), il est nécessaire d’installer des filtres à l’entrée des convertisseurs. Le dimensionnement optimal de ces filtres CEM nécessite une modélisation de l’ensemble du système de conversion d’énergie puis l’utilisation des modèles proposés dans des simulations de type circuit (SPICE …). Selon les cas où le système de conversion est déjà réalisé ou au stage de conception, il existe plusieurs méthodes de modélisation. Lorsque le système est déjà réalisé, la méthode, qui considère le convertisseur avec sa charge comme un modèle boîte noire, appelée “Terminal Modeling” est particulièrement adaptée dans ce cas. Dans ce papier, on met en évidence ses limites puis on propose un modèle de type boîte grise afin d'améliorer sa précision et sa robustesse jusqu'à 100MHz.

La montée en fréquence des convertisseurs statiques de puissance oblige à dimensionner les filtres de compatibilité électromagnétique en prenant en compte les éléments parasites de ces derniers. L’objectif est alors d’obtenir un modèle circuit de la bobine de mode commun sur une large plage de fréquence (150 kHz à 30 MHz ici), puis d’utiliser ce modèle pour dimensionner une bobine de mode commun pour le respect d’une norme (DO-160-B ici). L’équivalence circuit du modèle de Debye de la perméabilité magnétique complexe permet de simplifier le dimensionnement de l’inducteur avec la prise en compte de la chute de perméabilité avec la fréquence. La solution semi-analytique de la bobine optimale prend en compte la non-saturation du noyau, et le remplissage de la fenêtre de bobinage, le tout avec un coût de calcul modéré. La géométrie optimale est alors utilisée dans un modèle de la capacité parallèle équivalente de l’inducteur pour prédire avant réalisation sa valeur et la maintenir en deçà du maximum calculé pour le respect de la norme.

Les capacités parasites des bobines impactent leur impédance à haute fréquence. Un modèle semi-analytique de la capacité parasite équivalente pour des bobines à noyau conducteur (nanocristallin) est proposé pour expliquer son origine et la réduire, notamment pour des applications de filtrage pour la compatibilité électromagnétique (CEM) à haute fréquence. Une approche énergétique est utilisée pour calculer la capacité parasite équivalente à partir du nombre de tours et de la valeur des capacités parasites élémentaires issues de simulation éléments finis. Les erreurs relatives par rapport aux mesures montrent que le modèle proposé améliore la précision de la prédiction par rapport aux modèles classiquement utilisés dans la littérature et prend en compte correctement l’évolution avec le nombre de tours et les espacements inter-spires, et spire-noyau.

Les systèmes électriques embarqués dans les véhicules doivent satisfaire aux exigences normatives de compatibilité électromagnétique. Afin de s’en assurer, l’émission des interférences électromagnétiques est caractérisée par des méthodes de mesure normalisées. Les paramètres du récepteur de mesure, tels que la bande passante de résolution et le mode de détection, influent directement sur les résultats. De ce fait, pour réaliser des confrontations entre résultats de simulation et de mesure, la réponse du récepteur de mesure doit être prise en compte. La méthode proposée permet de modéliser cette réponse avec un faible temps de calcul. Le principe utilisé repose sur la transformée de Fourier à court terme et fournit des résultats en détection crête, quasi-crête et moyenne.

La méthode du produit des aires est très répandue pour le dimensionnement des composants magnétiques en électronique de puissance, grâce notamment à sa simplicité de mise en œuvre. Néanmoins, l’utilisation de cette méthode nécessite des itérations pour affiner le choix du noyau et la définition des bobinages afin de respecter les contraintes thermiques des composants. Dans cet article, la méthode du produit des aires est étendue pour pouvoir y incorporer la prise en compte des effets haute fréquence et les contraintes thermiques liées aux composants magnétiques planar. L’expression finale obtenue permet un dimensionnement plus efficace et plus rapide des composants planar en évitant les itérations liées aux contraintes thermiques. La différence entre les deux approches est illustrée au travers d’un exemple de dimensionnement de transformateur planar (100 kHz / 2 kW).

Les systèmes électriques embarqués dans les véhicules doivent satisfaire aux exigences normatives de compatibilité électromagnétique. Afin de s'en assurer, l'émission des interférences électromagnétiques est caractérisée par des méthodes de mesure normalisées. Les paramètres du récepteur de mesure, tels que la bande passante de résolution et le mode de détection, influent directement sur les résultats. De ce fait, pour réaliser des confrontations entre mesure et simulation, la réponse du récepteur de mesure doit être prise en compte. La méthode proposée permet de modéliser cette réponse. Le principe utilisé repose sur la transformée de Fourier à court terme et fournit des résultats en détection crête, quasi-crête et moyenne.

Ce papier propose une nouvelle méthode pour estimer les permittivités relatives qui permettent de calculer la capacité parasite des bobines toriques utilisées dans le filtrage CEM. Cette méthode est basée sur une association d’essais expérimentaux et des simulations éléments finis 2D sur FEMM permettant de déterminer les permittivités relatives des noyaux magnétiques en prenant en compte une éventuelle anisotropie. Ensuite, ce même logiciel a été utilisé pour estimer la capacité parasite équivalente de la bobine avec une faible erreur relative indépendamment du nombre de spires.

Les composants de puissance à base de GaN présentent un fort potentiel pour le développement de convertisseurs statiques fonctionnant à hautes fréquences. Les principales propriétés de cette filière technologique conduisent à une réduction de la taille, du poids et du volume des convertisseurs d’énergie. La conception de ces convertisseurs hautes fréquences (HF) repose sur des simulations nécessitant des modèles de composants actifs très précis. Afin d’obtenir ces modèles, une phase de caractérisation permettant d’obtenir les différents paramètres du modèle est nécessaire. Ce travail présente une méthode de caractérisation des transistors de puissance GaN basée sur la mesure de paramètres S à l’aide de dispositifs d’adaptation sur circuit imprimé ainsi que des mesures en régime pulsé.

Cet article présente une méthodologie permettant l’analyse des densités de puissance volumique qui peuvent être obtenues via l’utilisation de composants magnétiques planar au sein des convertisseurs d’électronique de puissance. En se basant sur une configuration optimale pour le transformateur, les densités de puissance volumique maximales atteignables pour différents noyaux magnétiques EE et E/PLT sont étudiées pour trois types de refroidissement : sans refroidisseur, refroidissement simple face et refroidissement double face. Ce type d’analyse peut être utile à un concepteur, lors d’une phase de dimensionnement, en le guidant vers des choix technologiques adaptés.

Ce travail de thèse s’inscrit dans le cadre de la collaboration entre l’IEMN et le L2EP sur la thématique de la montée en fréquence des convertisseurs statiques pour l’intégration de puissance. Les transistors de puissance à base de Nitrure de Gallium (GaN) offrent la possibilité de commuter de fortes puissances (au- delà d’1 kW) à hautes fréquences (au-delà d’1 MHz), permettant ainsi de réduire le volume des composants passifs des convertisseurs d’énergie. La conception des convertisseurs hautes fréquences par simulation nécessite de disposer de modèles de composants de puissance précis et valides sur une large plage de fréquence. Les techniques classiques de caractérisation et modélisation utilisées en électronique de puissance sont limitées en bande de fréquence et ne permettent pas de modéliser de façon précise tous les effets intrinsèques aux composants en hautes fréquences. L’objectif de ce travail est d’adapter les techniques utilisées dans le domaine de la caractérisation hyperfréquences pour la modélisation d’un transistor de puissance GaN. Dans le cadre de cette étude, le transistor GS66502B 650V/7.5A de type GaN HEMT sera utilisé pour la mise en place de notre méthode. La plage de fréquence visée pour la modélisation est 1 MHz – 1 GHz.

Ce papier propose une nouvelle méthode de dimensionnement de la bobine couplée du filtre de mode commun qui minimise son volume tout en tenant compte de la contrainte de la saturation du noyau magnétique. Les résultats de simulations obtenus, validés expérimentalement, montrent que, dans certains cas, augmenter la valeur de l’inductance jusqu’à une valeur optimale permet de réduire le volume du noyau magnétique tout en améliorant les performances des filtres CEM.

Les filtres CEM sont largement utilisés dans les convertisseurs statiques afin de respecter les normes CEM, ce qui augmente considérablement le volume et le coût des installations à cause de la bobine de mode commun. Ce papier présente une nouvelle méthode qui permet de calculer le volume minimal de la bobine couplée de mode commun en tenant compte des contraintes de la saturation du matériau magnétique. Les résultats obtenus montrent que, dans certaines applications, augmenter la valeur de l'inductance jusqu'à une valeur optimale permet de réduire le volume du noyau magnétique tout en améliorant l'atténuation du filtre.

The Ring core inductors are widely used in EMI filters within the aeronautic domain. To optimize, at the design step, the performances of the EMI-filters, a design tool is developed in which a lot of high frequency physical aspects are included. It's well known that the high frequency behavior of the inductors used in EMI filters is limited by the stray capacitance. In this paper, in order to develop a high frequency inductor model, three methods using finite elements method are detailed to calculate the stray capacitance value. These results are integrated into the inductor model that will be used in the EMI filter design tool.

Les composants magnétiques planar sont de plus en plus présents dans les convertisseurs de puissance en remplacement des composants bobinés classiques. L’aspect thermique de ces composants est essentiel pour un fonctionnement correct des structures de puissances. Dans cet article, un modèle thermique de transformateurs planar, basé sur un réseau nodal de résistances thermiques (RRT), est développé. Ce réseau est appelé structurel car toutes les résistances thermiques sont directement en lien avec la géométrie du composant. Les résultats de ce modèle seront comparés à des résultats issus de simulations par éléments finis ainsi qu’à des mesures expérimentales sur un prototype.

The performance of the EMI filter is characterized by the insertion loss (IL). Classical measurement of the IL is performed with 50Ω/50Ω even if the final application has not these impedances values. In this work, an experimental approach is used to determine the IL for arbitrary (input/output) impedances. The proposed method is based on a black-box model obtained from S-parameter measurements with 50Ω/50Ω, and then extended to determine the IL of the EMI.

Ce papier a pour objectif le dimensionnement d’un filtre CEM associé à un hacheur série utilisant des semi-conducteurs rapides au Carbure de Silicium SiC (diode et transistor JFET). Afin de respecter les normes CEM, une méthode de dimensionnement du filtre basée sur un modèle de type circuit électrique équivalent est proposée. Elle permet de déterminer les différentes valeurs des éléments du filtre à réaliser ainsi que les valeurs limites des éléments parasites des composants passifs à utiliser. Le dimensionnement du filtre est basé sur des simulations qui utilisent un modèle HF de l’ensemble du système de conversion d’énergie. Le but est d’étudier l’influence de la modification des chemins de propagation à cause de l’installation d’un filtre. Une solution est également proposée pour réduire les perturbations conduites qui apparaissent en haute fréquence provoquées par les commutations des composants SiC. Les mesures effectuées sur un convertisseur DC-DC, sans et avec filtre, montrent l’efficacité de la méthode de dimensionnement proposée.

Afin d’étudier les commutations du transistor SiC-JFET “ Normally-off ”, l’évolution des capacités inter-électrodes est présentée dans ce papier lorsque le composant est en régime désaturé. La capacité de contre-réaction Cgd est tout d’abord caractérisée par la méthode des pinces de courant et ensuite validée par la mesure à l’aide d’analyseur d’impédance. Ces méthodes de caractérisation sont ensuite appliquées à la mesure de la capacité de sortie Coss, et montrent une forte augmentation de capacité apparente en régime désaturé. L’influence de la résistance de grille interne est alors étudiée, soulevant la problématique de mesure des capacités inter-électrodes des composants de puissance lorsque le canal conduit. Les résultats de caractérisation permettent finalement la mise en oeuvre d’un modèle comportemental dont le comportement en commutation est validé par des mesures sur un hacheur buck.

Dans le domaine de la variation de vitesse, les perturbations conduites de mode commun sont les plus difficiles à maîtriser du fait des multiples chemins de propagation possibles. Ces perturbations peuvent être réduites à l’aide de filtres passifs qui sont généralement très volumineux. Une solution pour réduire la taille de ces filtres consiste à réduire les perturbations de mode commun à la source, à savoir la tension de mode commun induite par le convertisseur. C’est dans cette optique que s’inscrit cet article qui étudiera une stratégie de modulation permettant la synchronisation de tous les fronts de tension dans une structure onduleur-redresseur entièrement commandé. Avec l’utilisation de cette stratégie de synchronisation que l’on qualifiera de synchronisation totale (ST), il est possible de réduire la tension de mode commun à de simples résidus issus des commutations des différents bras de la structure. Dans cet article seront présentés les développements de la stratégie de synchronisation totale en vue d’une généralisation à tout point de fonctionnement du variateur ainsi qu’une étude de l’impact des résidus liés aux commutations des différents bras de la structure sur le contenu spectral de la tension de mode commun.

Cet article présente une méthodologie de calcul de capacités parasites pour un composant magnétique de type planar en 3 dimensions. La méthode proposée est basée sur la décomposition du champ électrique entre plusieurs conducteurs (EFD). Des formulations 2D utilisées en micro-électronique ont été étendues pour pouvoir être utilisées dans le cas de composants magnétiques planar. Le calcul en 3D basé sur une approche énergétique, en tenant compte des effets du matériau magnétique, a été proposé. Des prototypes d’inductances et d’inductances couplées ont permis de valider cette approche analytique.

Cet article présente une méthodologie pour l’identification automatique des éléments d’un circuit électrique équivalent à partir de mesures d’impédances. L’algorithme de détermination des paramètres électriques des composants magnétiques est basé sur une décomposition améliorée en fonction rationnelle (IRFA) qui permet de modéliser n’importe quel impédance (ou admittance) avec un degré de précision voulu. Cette décomposition est ensuite transcrite en circuit électrique équivalent de manière systématique en utilisant l’expansion de Foster. Tous ces outils ont été implantés dans une application logicielle pour permettre la caractérisation d’inductances de mode commun d’un filtre CEM. L’approche systématique peut permettre l’extension de cette méthode à tous les composants magnétiques.

Ce papier traite du dimensionnement d’un filtre CEM associé à un hacheur série utilisant des composants rapides au Carbure de Silicium (SiC). Les perturbations conduites engendrées par le convertisseur en mode commun et de mode différentiel sont importantes et nous amènent à utiliser un filtre en double T pour réduire les perturbations dans une large bande de fréquence. De plus pour les fréquences supérieures à 10MHz un soin particulier a été apporté au blindage de l’ensemble convertisseur-charge afin de réduire au maximum les perturbations hautes fréquences et respecter ainsi la norme EN55011 (classe B). Une méthode de dimensionnement du filtre est proposée. Elle permet de déterminer les valeurs des différents éléments du filtre en tenant compte des éléments parasites des composants passifs qui réduisent ses performances. Les mesures des perturbations effectuées sur le convertisseur, sans filtre et avec le filtre, montrent l’efficacité du filtre réalisé. Mots-clés : dimensionnement des filtres CEM, filtre de mode commun, filtre de mode différentiel, modélisation des inductances couplées, perturbations conduites.

Les convertisseurs statiques de puissance fonctionnent à des fréquences de plus en plus élevées. Ils génèrent des fronts raides de tension et de courant qui sont à l’origine de perturbations électromagnétiques conduites et rayonnées. Dans cet article, on s’intéresse aux perturbations conduites de mode commun et de mode différentiel. Pour réduire ces perturbations et respecter ainsi les normes CEM en vigueur, il est nécessaire d’utiliser des filtres CEM. L’objectif de ce papier est de proposer une méthode de caractérisation et de modélisation des inductances couplées utilisées dans les filtres CEM. La démarche proposée est basée principalement sur des mesures expérimentales afin de déterminer les paramètres du modèle du filtre. Ainsi, les modèles proposés sont du type circuit et seront utilisés pour le dimensionnement du filtre à l’aide du logiciel SPICE. Dans cette étude, nous proposons des modèles d’inductance couplée utilisée en mode commun et en mode différentiel. Les résultats de simulation sont comparés aux relevés expérimentaux obtenus en utilisant un dispositif expérimental spécifique. Les résultats obtenus montrent une bonne concordance entre les courbes simulées et les relevés expérimentaux dans la bande de fréquence variant entre 9 kHz et 30 MHz.

Cet article aborde l’étude des cellules de caractérisation destinées à déterminer les pertes d’insertion des filtres CEM secteur sous impédances variables. Nous présentons l’étude théorique, les réalisations et la méthode de mesure permettant de connaître l’évolution de l’efficacité attendue des filtres dans la bande de fréquence 100kHz à 100MHz. Nous mettons en évidence la spécificité de la mesure en mode commun et donnons des résultats comparatifs en fonction de la fréquence. Les cellules, de type mode commun ou de mode différentiel, réalisées au laboratoire sont décrites dans ce document.

Cet article propose de mettre en pratique la méthode de décomposition du champ électrique pour les conducteurs en technologie PCB, avec pour application, une évaluation analytique de l’effet capacitif des composants planars. En combinant des éléments de décomposition élémentaires, des formules analytiques ont été proposées pour étendre à l’électronique de puissance ces formulations déjà utilisées en micro-électronique. Les résultats obtenus ont été validés à l’aide de simulations FEM et de mesures d’impédances réalisées sur différents prototypes. Ces formules, simples et précises permettent d’envisager, à terme, le calcul analytique des capacités parasites des composants planar.

Depuis quelques années, les fréquences de fonctionnement des convertisseurs d’énergie ne cessent d’augmenter. Ceci est rendu possible grâce à l’utilisation des composants de puissance de plus en plus rapide. Ces composants modernes induisent de fortes variations de tension (dv/dt) et de courant (di/dt) durant les commutations. Ces fronts raides induisent des perturbations électromagnétiques conduites et rayonnées dans une large bande de fréquence. Dans le cadre de cette étude, nous nous intéressons uniquement aux perturbations rayonnées générées par un convertisseur DC-DC de type hacheur série. La structure étudiée est constituée de deux boucles localisées au niveau du circuit d’alimentation et du circuit de la charge. L’objectif est de mettre en évidence l’influence des topologies des deux boucles (du routage du circuit imprimé) sur le niveau du rayonnement électromagnétique.

L’objet de cet article concerne l’étude des perturbations électromagnétiques conduites générées par les convertisseurs statiques. L’objectif est de proposer une démarche permettant d’analyser l’influence du pont redresseur à diodes sur la propagation des perturbations conduites de mode commun et de mode différentiel vers le réseau électrique. Pour réaliser cette étude, des modèles haute fréquence du réseau électrique et du système de conversion statique ont été proposés. Les résultats de ce travail permettront l’optimisation du dimensionnement du filtre CEM à mettre à l’entrée du convertisseur en fonction des impédances réseau et

Le papier présente l’étude menée sur la caractérisation d’un transformateur de puissance dans le domaine temporel. Un modèle hautes fréquences de transformateurs de puissance a été proposé et la détermination de ses paramètres repose sur la mesure d’impédances aux entrées et sorties dans le domaine fréquentiel. La caractérisation de transformateurs de très haute puissance à l’aide de l’impédance mètre peut s’avérer assez difficile du fait des problèmes de connectique entre le transformateur de grande puissance et l’impédance-mètre. Il y a également un inconvénient lié à la limitation de la puissance fournie. De ce fait une méthode caractérisation des transformateurs à partir de mesures dans le domaine temporel est proposée. Des comparaisons entre des impédances obtenues par un traitement des signaux temporel et par mesure à l’aide d’un impédance-mètre sont présentées

Cet article présent une étude de caractérisation de l’impédance HF d’un câble rencontré dans les installations ou équipements utilisant des convertisseurs d’énergie de puissance. Nous présentons dans cette étude une méthode de caractérisation d’un câble bifilaire de puissance utilisé dans les chargeurs de batteries de forte puissance. Nous mettons en évidence la spécificité de la mesure en HF en présentant une démarche expérimentale permettant de déterminer l’impédance d’un câble d’énergie en fonction de ses caractéristiques géométriques en présence d’un plan métallique.

Cet article présente une nouvelle stratégie de modulation de largeur d’implusion (MLI) destinée à réduire les courants de mode commun générés dans les applications de variation de vitesse utilisant un onduleur à trois niveaux de type neutral-point-clamped (NPC). Il détaille le principe de la commande et son implantation dans un processeur par un modulateur à porteuses en dents de scie. Celui-ci permet de contrôler les degrés de liberté apportés par la stratégie.

Dans des travaux précédents, nous avons développé une méthode d’identification des paramètres pour un modèle comportemental des câbles d’énergie bifilaires, blindés ou non, soumis aux gradients de tension élevés créés par les convertisseurs électroniques de puissance. Dans cet article, nous appliquons la même méthode pour obtenir successivement le modèle d’un câble non blindé à 3 conducteurs, puis d’un câble blindé à 4 conducteurs. Les modèles obtenus sont validés dans les domaines fréquentiel et temporel. Ces modèles permettent d’identifier les chemins de propagation des courants de mode commun et de mode différentiel, et de prédéterminer les surtensions provoquées par les interrupteurs de puissance à semi-conducteur, de sélectionner les câbles les mieux adaptés ou les moyens les plus adaptés pour les réduire.

Les commutations des composants semi-conducteurs de puissance sont les principales sources de perturbations conduites dans un convertisseur d’énergie. Ces émissions utilisent les liaisons filaires pour se propager. Afin d’étudier l’influence des caractéristiques du câble d’énergie dans la propagation des perturbations conduites dans un convertisseur de puissance, il est nécessaire d’utiliser un modèle précis des liaisons filaires en tenant compte des différents phénomènes qui apparaissent lorsque la fréquence de commutation augmente. Dans cet article, nous nous intéressons uniquement à la modélisation du câble d’énergie bifilaire. Le modèle proposé est de type circuit (à constantes réparties) qui tient compte des effets de peau, de proximité et des pertes diélectriques. Le modèle obtenu est simulé avec le logiciel SPICE dans les domaines fréquentiel et temporel.

Depuis quelques années, les convertisseurs d’énergie utilisent des composants de puissance fonctionnant à des fréquences de plus en plus élevées pilotés par des commandes «rapides». Les commutations des interrupteurs induisent des variations rapides de courant et de tension qui excitent les éléments parasites du circuit de puissance provoquant des émissions électromagnétiques dans de larges bandes de fréquence. La propagation de ces perturbations dans le circuit (perturbations conduites) s’effectue de différentes manières en fonction de la disposition des éléments du système. L’objet de cette étude est l’identification des sources et des différents couplages dominants, en fonction de la hauteur des éléments et de la position angulaire des câbles d’entrée-sortie d’un chargeur de batteries.

It is well known that GaN device dynamic ON-state resistance would increase when device is operated in high frequency power converter, where device is possibly operated by zero voltage switching (ZVS) to reduce turn-ON switching losses. When device finishes ZVS during one switching period, it has been operated under both reverse and forward conduction. Therefore, its dynamic Rdson needs to be carefully measured under both conduction modes to understand device power losses. For this reason, a measurement circuit with simple structure and fast dynamic response will be presented to measure device reverse and forward Rdson. In order to improve measurement sensitivity, a trapezoidal current mode will also be presented to characterise device Rdson under almost constant current, which resolves measurement circuit sensitivty issue caused by parasitic inductance and measurement probes deskew.

GaN transistors have been attracting much attention in recent years due to their significant benefits on the reduction of conduction and switching losses in power converters. However they suffer from current collapse effect due to trapped charges that notably impairs on-state resistance, as largely discussed in literature. This work focuses on commutation and shows that current collapse also impacts the switching waveforms of GaN transitors, notably increasing switching losses at turn-on. The influence on gate instability at turn-off is also discussed, showing that conventional double-pulse test may be misleading when measuring switching transitions. Theoretical analysis is validated by experimental measurements using a modified double-pulse test to evaluate the influence of current collapse on switching waveforms.

Les composants magnétiques planar sont de plus en plus présents dans les convertisseurs de puissance en remplacement des composants bobinés classiques. L’aspect thermique de ces composants est essentiel pour un fonctionnement correct des structures de puissances. Dans cet article, un modèle thermique de transformateurs planar, basé sur un réseau nodal de résistances thermiques (RRT), est développé. Ce réseau est appelé structurel car toutes les résistances thermiques sont directement en lien avec la géométrie du composant. Les résultats de ce modèle sont comparés à des résultats issus de simulations par éléments finis ainsi qu’à des mesures expérimentales sur un prototype.

Les commutations des composants semi-conducteurs de types MOSFET et IGBT sont les principales sources de perturbations électromagnétiques dans un convertisseur électronique de puissance. Les variations rapides de tension et de courant excitent les éléments parasites du dispositif en provoquant l’apparition de courants HF de mode commun et de mode différentiel.
Généralement les perturbations conduites utilisent les liaisons filaires pour se propager dans l’ensemble du système. L’identification préalable des chemins des courants perturbateurs, dans les domaines fréquentiel et temporel, à l’aide d’outils de simulation, nécessite l’utilisation de modèles HF de chaque élément du dispositif. Les divers logiciels de type circuit proposent souvent des modèles de lignes qui ne tiennent pas compte de l’évolution des paramètres linéiques du câble d’énergie en fonction de la fréquence.
Nous proposons une méthode de modélisation des câbles d’énergie blindés et non blindés dont les paramètres linéiques sont déterminés à l’aide de 3 méthodes : formulations analytiques, code de calcul éléments finis et mesures au pont d’impédance.
La méthode de modélisation proposée tient compte de l’évolution des paramètres linéiques des câbles en fonction de la fréquence. Afin de renseigner les modèles sur les propriétés des matériaux des câbles, nous avons utilisé les résultats de mesures expérimentales pour améliorer le modèle. Ainsi, à partir des relevés expérimentaux et d’outils mathématiques, les paramètres R(f), L(f), C(f) et G(f) sont modélisés à l’aide de circuits électriques équivalents.
Les modèles de câbles blindés et non blindés obtenus sont validés dans les domaines fréquentiel et temporel dans une application de type variateur de vitesse.

L’objectif du brevet est de proposer une topologie de machine permettant de solutionner ce type de défis avec un focus sur des machines sans refroidissement par circulation par pompe de fluide liquide. L’intégration de l’électronique de puissance dans les machines posent les défis suivants :  Thermique à savoir la compatibilité concernant les différents composants présents à l’intérieur de la machine intégrée : le passage « actuel » aux composants de puissance Grand Gap supportant normalement des températures plus élevées que les composants Si et plus compatibles à celles que supporte la machine doit permettre l’intégration sans diminution des performances de la machine seule. A noter qu’il ne faut pas oublier les composants petits signal pour les contraintes en température  Compatibilité électromagnétique : s’il n’y a moins de problème de compatibilité électromagnétique à l’extérieur (uniquement deux fils parcourus par courant continu) , les contraintes se retrouvent à l’intérieur de la machine  Fiabilité fonctionnelle du drive du fait de l’augmentation de la complexité structurelle du drive électrique avec des contraintes thermiques et électromagnétiques

méthode de modulation permettant de limiter les perturbations CEM engendrées par la modulation des convertisseurs MLI

Ce mémoire présente une synthèse de mes travaux de recherche qui portent sur la modélisation comportementale des composants actifs et passifs, pour les convertisseurs statiques, et son application à l’étude des perturbations électromagnétiques. La première partie de mes activités de recherche a porté sur l’étude des mécanismes de commutation des Interrupteurs Bidirectionnels en Tension et en Courant (IBTC) à l’aide de modèles comportementaux. L’objectif était de réduire les contraintes en courant et en tension sur ces interrupteurs en agissant sur la commande des transistors. Les résultats de ces travaux nous ont conduit à proposer une nouvelle commande rapprochée appelée CATS (Commande Autour de la Tension de Seuil) qui permet de contrôler les commutations à la mise en conduction et au blocage des transistors à grille isolée de type MOSEFT et IGBT. Utilisée avec des IBTC, cette commande a permis le fonctionnement en toute sécurité d’un convertisseur AC-AC avec une maîtrise complète des contraintes, en tension et en courant, subies par les différents composants semi-conducteurs, augmentant par la même occasion leur fiabilité. La commande CATS a trouvé également son application dans la réduction des perturbations électromagnétiques générées par un convertisseur statique dont la commutation des composants de puissance est la source principale. La seconde partie de mes travaux de recherche a été consacrée à l’étude par simulation des perturbations électromagnétiques générées par un système de type variateur de vitesse afin de mettre en place les moyens de protection adéquats. Pour cela, nous avons proposé des méthodes d’identification des paramètres des modèles comportementaux : du convertisseur, des câbles d’énergie blindés et du moteur asynchrone. La simulation globale du variateur de vitesse, dans le domaine temporel et fréquentiel, a permis d’identifier les chemins de propagation des perturbations conduites dans l’ensemble du système. En utilisant cet outil de simulation, nous avons proposé des solutions pour réduire ces émissions en agissant sur la stratégie de commande du convertisseur.

This research work is supported by center research exchange scheme between the University of Nottingham and University of Lille in France. It is proposed an improved characterisation method to measure GaN-HEMT dynamic ON-state resistance quickly (less than 100 nanoseconds) after device OFF-state to ON-state transition (in comparison to 1 microsecond of authors' previous work). GaN-HEMT dynamic ON-state resistance is thus evaluated in megahertz high frequency switching power converter when device is in soft switching (in comparison with 10kHz hard switching power converter of previous work) to compare with device static ON-state resistance.

It is proposed a novel GaN-HEMT modelling method by using S-parameters to characterise device inter-electrode capacitances and terminal contact resistances.Afterwards, the model is implemented into virtual prototyping software. By co-simulation with electromagnetic models generated of the VP software, device switching waveforms are then obtained and they are compared with commercial ADS software and experimental measurement.

Common mode voltages generated by adjustable-speed drives create common mode currents which damage electric machines and require expensive filters. Usual ways to cope with this issue are based mainly on filtering and designing appropriate converters. However, recent development on power electronics shows that solutions can also be developed on PWM strategies. Thus, the presented work aims at elaborating a suitable PWM strategy for the reduction of common mode currents in three levels Neutral-Point-Clamped (NPC) inverters. The proposed new PWM appears to be a compromise solution between the quality of low frequency voltage supply (output Total Harmonic Distortion: THD) and high frequency conducted emissions (Electro-Magnetic Compatibility: EMC). The principle of the method is to lower the number of variations of the common mode voltage by introducing simultaneous commutations, so that the common mode voltage is not affected during the switching. As a consequence, the associated common mode current of the commutations is cancelled. The particularity of this PWM strategy, compared with previous ones, is that the double commutation is permanently controlled and adapted so as to ensure its perfect synchronism by avoiding dead time effects. The novel strategy has been implemented on an experimental bench using a carrier-based modulator and validated through common mode current measurements in both temporal and frequential domains. This research results from a co-operation between Schneider Electric, STIE (Schneider Toshiba Inverter Europe) and the L2EP (Laboratoire d’Electrotechnique et d’Electronique de Puissance de Lille), and focuses on the theme of adjustable-speed drives with reduced electromagnetic emissions. It is financed by Schneider Electric for one part and by the French State and the Région Nord-Pas-de-Calais for the other part. The new PWM strategy has been the subject of a patent deposit from Schneider Electric in 2006.

The first part of the chapter will present the global aspect of the railway power infrastructures and specially the power supply substation. The goals of this study consist in proposing a high frequency model of the railway systems and verifying by simulation the conformity with the EMC standards. Thus, each component of the railway power infrastructure (transformer, power rectifier) is modeled and the simulation results of the conducted emissions are compared to measurements on a reduced scale of the power supply substation.