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For the requirements of in-wheel traction systems, a new motor is proposed based on a specific property of multiphase machines: the ability in vector control to develop smooth torque at low speeds by using simultaneously the first and third harmonics to generate p and 3p polarities. From an initial fault-tolerant seven-phase axial–flux machine with two outer axial rotors for small vehicles such as moto/scooter is born the proposed motor just by adding magnets in the cylinder closing the two 2p-pole axial rotors of initial in-wheel motor, this addition creates thus a third radial rotor with 6p poles without changing the global volume. With an increase by 51% of the torque density, this more expensive motor can be considered in comparison with the initial in-wheel motor as a modular solution. With the same volume, a higher torque for higher acceleration and slopes can be obtained. The possibility to use different polarities with a strong non-sinusoidal back-emf without torque ripples is verified in 3D-FEM simulation and in a manufactured 28 slots – 12/36 poles prototype. Experimental results are given to prove the effectiveness of the proposal.

In order to improve the driving performance of electric vehicles (EV), a permanent magnet synchronous motor with double V-shaped magnet structure (DVMPMSM) and its driving system are studied in this paper. A 150 kW DVMPMSM for EV is designed firstly, and the design parameters of the motor are determined. In order to overcome the drawbacks of the finite element analysis (FEA), especially the issue on calculating time, a dynamic equivalent magnetic network (EMN) model of the DVMPMSM is constructed, by which the air gap flux density, back electromotive force, electromagnetic torque and winding inductance parameters of the motor can be solved. Compared with the FEA, the dynamic EMN model constructed in this paper greatly increases the calculation speed while the calculation accuracy is maintained well. This paper also introduces the stator winding switching method to replace the field-weakening control method. Then, a vector control method of DVMPMSM based on dynamic EMN model and stator winding switching is proposed. The demands brought forward by EV for high torque output under low speed and high upper limit of speed can be well satisfied. Finally, the accuracy of the dynamic EMN model and the effectiveness of the proposed control method is validated through prototype experiments.

As one of the key components, low-speed direct-drive in-wheel machines with high compact volume and high torque density are important for the traction system of electric vehicles (EVs). This paper introduces four different types of outer-rotor permanent magnet motors for EVs, including one five-phase SPM machine, one three-phase IPM machine with V-shaped PMs, one seven-phase axial flux machine (AFM) of sandwich structure and finally one hybrid flux (radial and axial) machine with a third rotor with V-shaped PMs added to the AFM. Firstly, the design criteria and basic operation principle are compared and discussed. Then, the key properties are analyzed using the Finite Element Method (FEM). The electromagnetic properties of the four fractional slot tooth concentrated winding in-wheel motors with similar dimensions are quantitatively compared, including air-gap flux density, electromotive force, field weakening capability, torque density, losses, and fault tolerant capability. The results show that the multi-phase motors have high torque density and high fault tolerance and are suitable for direct drive applications in EVs.

For non-sinusoidal electromotive force (NS-EMF) multiphase machines, this paper proposes a new strategy and control scheme to guarantee smooth torque under an open-phase fault. Notably, the conventional proportional-integral (PI) controllers implemented for vector control in healthy mode can be used in the faulty mode. The strategy is based on reduced-order transformations while the control scheme applies a simple artificial intelligence algorithm using a specific online-trained Adaptive Linear Neuron (ADALINE). Indeed, the inputs of ADALINE require the knowledge of rotor position and NS-EMF harmonic rank to optimize the learning time. The proposed strategy and control scheme are tested on a seven-phase machine with a strong Total Harmonic Distortion (THD) of NS-EMFs, containing numerous harmonics Hk (THD=38% with 100% H1, 32.3% H3, 9.4% H7, 12.5% H9, 10.3% H11). Numerical and experimental results are presented in this paper. This paper is accompanied by a video demonstrating the experimental results.

Fault tolerance has been known as one of the main advantages of multiphase drives. When an open-circuit fault happens, smooth torque can be obtained without any additional hardware. However, a reconfiguration strategy is required to determine new reference currents. Despite advantages of non-sinusoidal electromotive forces (NS-EMFs) such as high torque density, multi-harmonics existing in NS-EMFs cause more challenges for control, especially under faulty conditions. Therefore, to guarantee high-quality vector control of multiphase drives with multi-harmonic NS-EMFs, this two-part study proposes control schemes using adaptive linear neurons (Adalines) to adaptively eliminate torque ripples. The proposed simple Adalines are efficient because of taking advantage of the knowledge of rotor position and of torque harmonic rank induced by the NS-EMFs. The control scheme using an Adaline for healthy mode was described in part I of this study. In this second part, the control scheme using another Adaline for an open-circuit operation, under the impacts of multi-harmonics in NS-EMFs, is proposed. Notably, smooth torque and similar copper losses in the remaining healthy phases can be obtained. Experimental tests are carried out on a seven-phase permanent magnet synchronous machine (PMSM) with a high total harmonic distortion (THD = 38%) of NS-EMFs. A demonstration video is provided with this paper.

This two-part study proposes a new sensorless control strategy for non-sinusoidal multiphase permanent magnet synchronous machines (PMSMs), especially in integrated motor drives (IMDs). Based on the Sliding Mode Observer (SMO), the proposed sensorless control strategy uses the signals (currents and voltages) of all fictitious machines of the multiphase PMSMs. It can estimate the high-accuracy rotor position that is required in the vector control. This proposed strategy is compared to the conventional sensorless control strategy applying only current and voltage signals of the main fictitious machine, including the fundamental component of back electromotive force (back-EMF) of the non-sinusoidal multiphase PMSMs. Therefore, in order to choose an appropriate sensorless control strategy for the non-sinusoidal multiphase PMSMs, these two sensorless control strategies will be highlighted in terms of precision in the rotor position and speed estimations. Simulation and experimental results of a non-sinusoidal seven-phase PMSM will be shown to verify and compare the two sensorless control strategies. In this part of the study (part I), only the sensorless control in medium and high-speed range is considered. The sensorless control at zero and low-speed range will be treated in the second part of this study (part II).

This paper proposes a sensorless control strategy based on Sliding Mode Observer (SMO) for a Five-phase Interior Permanent Magnet Synchronous Machine (FIPMSM), with a consideration of the third harmonic component. Compared to conventional three-phase machines, the third harmonic of back electromotive force (back-EMF) contains more information. Thus, in this paper, the first and third harmonic components of the five-phase machine are considered to estimate the rotor position which is necessary for the vector control. Simulation results are shown to verify the feasibility and the robustness of the proposed sensorless control strategy.

More degrees of freedom not only enable multiphase drives to be fault-tolerant but also allow non-sinusoidal electromotive forces (NS-EMFs) in high-quality vector control. NS-EMFs lead to lower costs of design and manufacturing of electrical machines. However, the presence of multi-harmonics in NS-EMFs possibly generates pulsating torque in both healthy and faulty conditions of multiphase drives. To facilitate the use of NS-EMFs, this two-part study proposes control schemes to adaptively improve torque quality of multiphase drives in dealing with multi-harmonics of NS-EMFs. The proposed schemes are based on a simple but effective type of artificial intelligence, Adaptive Linear Neuron (Adaline). The knowledge of multiphase drives including the harmonic ranks of NS-EMFs and the rotor position is exploited to design the online-trained optimal Adalines. The first part of this study is to propose a control scheme using an Adaline for healthy mode with high-quality torque regardless of numerous harmonics in NS-EMFs. The second part of this study introduces a control scheme using another Adaline for open-circuit faults. The proposed schemes are numerically and experimentally validated on a seven-phase permanent magnet synchronous machine (PMSM) possessing a high total harmonic distortion (THD=38%) of NS-EMFs. A demonstration video is provided with this paper.

In this paper, a novel five-phase fractional-slot concentrated winding (FSCW) with 20-slot/22-pole is presented. It benefits not only the advantages of conventional FSCW, but also weak space harmonics of magnetomotive force (mmf). The winding allows eliminating the 1st sub-order harmonic. The new layout of the winding topology is obtained by a combination of stator shift technique of the winding in the slots with a special coupling of the windings (star-pentagon), using winding function theory. The high performances of the new winding layout are validated using finite element method (FEM). Compared to the conventional winding, the winding factor and the THD of mmf are improved by 1.3% and 2.2%, respectively. With the same injection of current density, the average output torque is increased by 1% and the torque ripple is decreased by 60%. The eddy current losses in the PMs at rated speed (600 rpm) and 2100 rpm speed are improved by 67% and 56%, respectively.

This paper investigates a real-time fault diagnostic of a transportation system which needs two drives with fault-tolerance capabilities. Because of constraints on the mass of the system and on the cost of the Voltage Source Inverter (VSI), a drive with two Six-Phase Permanent Magnet Synchronous Machines (PMSM) in series-connection supplied by two six-leg inverters is chosen. Despite the serial -connection, independent control of the two machines and fault –tolerance to open-switch fault is ensured. Nevertheless, a Fault Detection Identification (FDI) process is required for analysis and/or control reconfiguration. The proposed FDI is based on the combination of different criteria obtained from the two zero-sequence currents and from the normalized currents mapped into two frames defined by the Concordia Transformation. Results obtained from simulation and experimental tests show the effectiveness of the proposal.

In the context of future Permanent Magnet Synchronous Machines (PMSMs) with a high number of phases (>7) in integrated drives, this paper proposes several control strategies when multiphase PMSMs with non-sinusoidal back electromotive forces (back-EMFs) operate in healthy and open-circuit faults. In all operation modes, the considered constraint on current is related to the maximum root mean square (RMS) current allowable in one phase of the machine. The constraint on voltage limits the maximum peak value of the phase voltage determined by the DC-bus voltage of the converter. When one or two phases are open-circuited, to maximize torque and respect the constraints, new current references obtained by several proposed methods in rotating and natural frames are imposed to the machine. Due to the non-sinusoidal waveform of back-EMFs and the considered constraints, numerical computations based on analytical formulations are required to obtain maximal torque-speed characteristics, including the flux-weakening operation. The usefulness of the proposed strategies is verified by numerical and experimental results.

This paper proposes several easy-to-implement control strategies when seven-phase axial flux brushless DC machines with trapezoidal back electromotive forces operate in normal and faulty modes by taking into account constraints on voltage and current. The constraints are related to the converter and machine design in terms of maximum values of current and voltage. The considered faults are cases in which one or two phases of the machine are open-circuited. Numerical computations based on analytical formulations are applied to obtain torque-speed characteristics, including the flux-weakening operation. The methods determine current references to ensure the torque optimizations while currents and voltages are within their limits. The usefulness of the methods is verified by numerical results.

Multiphase machines have recently gained interest in the research community for their use in applications where high power density, wide speed range and fault-tolerant capabilities are required. The optimal control of such drives requires the consideration of voltage and current limits imposed by the power converter and the machine. While conventional three-phase drives have been extensively analyzed taking into account such limits, the same cannot be said in the multiphase drives’ case. This paper deals with this issue, where a novel two-stage Model Predictive optimal Control (2S-MPC) technique is presented, and a five-phase permanent magnet synchronous multiphase machine (PMSM) is used as a case example. The proposed method first applies a Continuous-Control-Set Model Predictive Control (CCS-MPC) stage to obtain the optimal real-time stator current reference for given DC-link voltage and stator current limits, exploiting the maximum performance characteristics of the multiphase drive. Then, a Finite-Control-Set Model Predictive Control (FCS-MPC) stage is utilized to generate the switching state in the power converter and force the stator current tracking. An experimental validation of the proposed controller is finally provided using a real-time simulation environment based on OPAL-RT technologies.

High cost, no-ideal driving range and charge time limit electric vehicle market share. Facing these challenges, an integrated motor drive/battery charger system has been proposed by Valeo. A further advancement, based on this system, is present in this paper; for the first time, the integration of traction, charging and air-compressor supply modes is proposed and tested by real-time experimentation. This integrated system is expected to increase the vehicle component compactness and power, therefore potentially reduce the cost and battery charging time. An overall and unique control scheme is detailed to achieve the three main operating modes: traction, charging and air-compressor supply modes. The real-time experimentation results show the system feasibility.

This paper presents an extension of previous methods in order to find electrical series-connections between multiphase machines allowing the independent control of each one of them. These new electrical series-connections explore the symmetrical disposition of the phases of even-multiphase machines, allowing the inversed connection of some of the phases, different from the direct connections as it was previously done. Therefore, electrical series-connections of two symmetrical 6-phase or of four symmetrical 10-phase machines are now possible. Besides that, this new solution ensures a natural independent control of permanent magnet synchronous machines even if the back-electromotive forces generated by the rotor are not sinusoidal, without need of special machine conception or supplementary control strategy. This control independency is mathematically proved using the decomposition of multiphase machines in fictitious diphase and homopolar machines. Experimental results are presented to show the functioning and the advantages of this new coupling for two symmetrical 6-phase permanent magnet synchronous machines.

This paper proposes a procedure that is suitable for experimental investigation of real-time open-switch and open-phase faults diagnosis of a five-leg Voltage Source Inverter (VSI) feeding a five-phase bi-harmonic Permanent Magnet Synchronous Machine (5-Φ B-PMSM). The algorithm is based on the specific characteristics of multiphase machines, which allows inverter fault detection with sufficient robustness of the algorithm in the presence of fundamental and third harmonic components. Firstly, the inverter fault effects analysis is achieved in the characteristic subspaces of the five-phase PMSM. Specificities that are interesting for the elaboration of a real-time Fault Detection and Identification (FDI) process are highlighted. Original and particular algorithms are used for an accurate two-dimensional normalized fault vector extraction in a defined fault reference frame. This frame is dedicated only for fault detection and identification. To ensure the high immunity of the FDI process against transient states, a particular normalization procedure is applied. The normalized diagnostic signals are formulated from the defined frame and others variables derived from the reference and measured currents. Simulation and experimental results of open-switch and open-phase faults are provided to validate the proposed algorithm.

This paper analyzes two fault-tolerant dual-multiphase motor drives, a series connected topology and a standard H-bridge topology. Previous studies have shown that the series connected topology is appropriate to an aerospace application and has lower peak current in degraded mode in comparison with the H-bridge topology, which may consequently diminish the system’s weight and cost. This paper extends the study to compare different control strategies of these structures under two fault conditions: short-circuit of an inverter’s switch and an open-phase of the machine. The control strategies analyzed in this paper do not impact the fundamental current or the torque generation, but the amplitudes of some harmonics in degraded mode are expected to be narrowed down in order to reduce the inverter’s size. Some analyses of maximum voltage and peak current in degraded mode have been used for inverter dimensioning. Experimental results are shown and compared to the simulated ones to confirm the validity of this study.

This paper proposes a novel variable speed control strategy of a particular 5-phase Permanent Magnet Synchronous Generator (PMSG) in healthy and faulty modes by taking into account the constraints on voltages and currents. These constraints are related to the converter and machine design. The considered faults are open-circuited phases (one phase, two adjacent phases and two non-adjacent phases). A variable speed control strategy is presented, including flux weakening operations. Based on analytical formulations, a numerical computation is proposed to bring out the torque-speed characteristics. This method allows the determination of the current references which ensure the functioning of a 5-phase PMSG at variable speed while keeping phase voltages and currents below their limits. Theoretical, numerical and experimental results are presented. These results are compared in order to validate the proposed approach.

A novel centroid-based diagnostic method of the power switches in five-leg Voltage Source Inverter (VSI) is proposed in this paper. Using a vectorial multi-machine description, a five-phase drive presenting an opened switch or an opened phase faults has typical operating characteristics in comparison to classical three-phase drives. Based on such characteristics, this work aims to provide a simple and robust diagnostic process for switches fault regardless of the shape of the back-EMFs (harmonic components) and the transient states due to the load variation. Original theoretical developments are presented. Experimental results are shown to validate the proposed strategy.

This paper proposes a new method based on Artificial Neural Networks for reducing the torque ripple in a non-sinusoidal Synchronous Reluctance Motor. The Lagrange optimization method is used to solve the problem of calculating optimal currents in the d-q frame. A neural control scheme is then proposed as an adaptive solution to derive the optimal stator currents giving a constant electromagnetic torque and minimizing the ohmic losses.Thanks to the online learning capacity of neural networks, the optimal currents can be obtained online in real time. With this neural control, each machine’s parameters estimation errors and current controller errors can be compensated. Simulation and experimental results are presented which confirm the validity of the proposed method.

Multi-phase machines are well-known for their fault tolerant capability. Star-connected multiphase machines have fault tolerance in open-circuit. For inverter switch short-circuit fault, it is possible to keep a smooth torque of Permanent Magnet Synchronous Machine (PMSM) if the currents of faulty phases are determined and their values are acceptable. This paper investigates fault-tolerant operations of an open-end five-phase drive, i.e. a multi-phase machine fed with a dual-inverter supply. Inverter switch short-circuit fault is considered and handled with a simple solution. Original theoretical developments are presented. Simulation and experimental results validate the proposed strategy.

This paper presents a new method for online symmetrical components and phase-angle extraction from high-voltage transmission-line faults. This method is based on the Adaline neural networks and the instantaneous power theory, also known as the p-q method. A new current decomposition is proposed in order to derive the direct, inverse, and homopolar current components. The average and oscillating terms of powers in the αβ frame are separated by using four Adaline neural networks. The Adalines use a cosine and sine as inputs in order to learn the linear combination of the powers. The resulting symmetrical components are used by three other Adalines for phase-angle estimation between direct and inverse current components. These phase angles permit classifying the fault types. The neural networks use an online learning process-based Widrow-Hoff algorithm and can adapt their weight parameters to the power-supply evolution. Simulation results show the performance and the robustness of this method and provide a perspective for protection relay improvement.

This study proposes several high precision selective harmonics compensation schemes for an active power filter. Harmonic currents are identified and on-line tracked by novel Adaline-based architectures which work in different reference-frames resulting from specific currents or powers decompositions. Adalines are linear and adaptive neural networks which present an appropriate structure to fit and learn a weighted sum of terms. Sinusoidal signals with a frequency multiple of the fundamental frequency are synthesized and used as inputs. Therefore, the amplitude of each harmonic term can be extracted separately from the Adaline weights adjusted with a recursive LMS (Least Mean Squares) algorithm. A first method is based on the modified instantaneous powers, a second method optimizes the active currents, and a third method relies on estimated fundamental currents synchronized with the direct voltage components. By tracking the fluctuating harmonic terms, the Adalines learning process allows the compensation schemes to be well suited for on-line adaptive compensation. Digital implementations of the identification schemes are performed and their effectiveness is verified by experiments.

This paper presents the design, analysis and control of an original low speed and high torque five-phase external rotor permanent magnet synchronous machine (PMSM) applied for the direct drive of coal conveying system. Firstly, the design considerations including the windings factors and the magnetomotive force (MMF) are given. Secondly, according to the performance requirements, the preliminary dimensions of the machine are firstly calculated using the magnetic circuit method, and then optimized using a Kriging model optimization strategy. Thirdly, the performances of the proposed five-phase PMSM are given and compared to a traditional three-phase PMSM, including both the no-load and on-load conditions using finite element method (FEM). An increase of 22.3% for the output torque with same copper losses is found. Keeping low torque ripples, the torque density of the five-phase machine can be still improved by 14.6% by injection of third harmonic current with same resultant peak current. Finally, a 5-phase, 40-slot, 44-pole prototype is fabricated, and the expected performance of the prototype is analyzed through experiments.

T-type multilevel inverters are a potential alternative because of their increased efficiency and low conduction losses. A conventional two-level inverter is extended with a bidirectional active switch to form a T-Type topology. There are a few T-Type MLIs formulated based on requirements and applications. This work provides a comparative analysis of three different T-Type five-level MLIs with a five-level cascaded H-Bridge converter. Four multi-carrier pulse width modulation (PWM) strategies, i.e., phase disposition PWM (PDPWM), phase opposition disposition- PWM (PODPWM), alternate phase opposition disposition-PWM (APODPWM), and Hybrid PWM schemes are implemented to evaluate the performance of these MLIs. They are operated over a wide range of modulation indices, and the converter output voltage, total harmonic distortion (THD), and characteristics are observed. MATLAB\Simulink environment is used for this comparative performance analysis.

At low speed, the traditional high frequency signal injection (HFSI) control strategy will lead to large torque ripple, and affect the estimation accuracy of the position/speed related to sensorless control algorithm, and finally lead to the problem of the system stability. Based on the characteristics of sevenphase Permanent Magnet Synchronous Machine (PMSM), this paper proposes a new sensorless control strategy in full speed range. In the zero/low speed range, HFSI method is applied to the 5th harmonic subspace, which reduce the torque ripple of the machine.. In the medium/high speed range, the sliding mode observer (SMO) is used in the 1st harmonic subspace to estimate the speed and position of the machine. The influences between the two methods are effectively reduced when exchanging from zero/low speed to medium/high speed range. Moreover, the estimated position and speed is more accurate and the torque ripple is smaller with the proposed sensorless control strategy. Finally, the effectiveness of the proposed strategy is verified by simulation results.

This paper presents a new approach to control properly the currents of a dual three-phase PMSM operating in open-circuit fault condition with a wide speed range. Using fault tolerant control strategies proposed in the literature lead to high frequency current components in the rotor frame. Operating at high speed required in some industrial applications induces a strong constraint on the current controllers. In this paper, a second transformation matrix resulting constant currents in the new frame is proposed. However, there is still a coupling between axes. Thus, a simple Adaptive Linear Neuron is proposed to decouple and enhance the performance of the current tracking. Comparative simulation results are shown for a 12slots/8poles dual three-phase PMSM to confirm the validity of the proposed method.

In previous research, a novel three-phase dual-stator axial flux permanent magnet machine characterized by the advantages of compact structure and low moment of inertia is proposed for industrial robot application. In order to improve its functional reliability furtherly, the dual threephase axial flux permanent magnet machine (DTP-AFPM) is firstly proposed. Benefiting from the combination of 12 slots/10 poles, the coil configuration of one stator disk can be modified to a dual three phase full-pitch winding straightforwardly, as a result, one kind of the DTP-AFPMs is achieved which is named as the no shift model in this paper. For eliminating the coil reconfiguration on each stator disk and the connection of the coils belonging to the same phase between two stator disks, the shift model which is based on the shift of the two stator disks to obtain the phasor difference between two three-phase windings is introduced. The characteristics and electromagnetic performances of these two models are analyzed and compared. However, it should be noted that the light-weight disk-type rotor of DTP-AFPMs also degrade the strength of the rotor. The proposed DTPAFPMs are more sensitive to the axial stress on the rotor which introduces not only the vibration and noise but also the deformation or even the damage of the rotor. Thus, the axial stress on the rotor is investigated and treated as a critical evaluation indicator. The axial stress is analyzed under both healthy and fault conditions and its distribution on the rotor is given on a 2-D plane.

In this paper, a novel topology of five-phase fractional-slot concentrated winding (FSCW) with selective magnetomotive force (MMF) harmonic elimination is proposed. Compared to traditional FSCW with stator shift technique, not only the parasitic sub- or sup-order harmonics of the MMF can be selectively reduced or eliminated, the non-overlapping characteristic is also kept. Firstly, based on 20-slot/22-pole single-layer (SL) winding topology, a dual five-phase 40-slot/22-pole one of SL winding with 1 st harmonic elimination is introduced. Secondly, a new 40-slot/22-pole of double-layer with selective harmonic reduction is presented. Finally, the high performances of the machine with the proposed winding topology are evaluated using finite element analysis (FEA), including air gap flux density, output torque, machines losses, etc.

For in-wheel machine, outer rotor machines appear as a natural solution. Practically these machines are either radial-flux with one rotor or axial-flux with two rotors. The paper is proposing a machine with three outer rotors with two different polarities in order to reduce useless end-windings while keeping an acceptable thickness for the radial-flux rotor and high torque quality. This Hybrid Flux Permanent Magnet original structure (named HFPM) is possible thanks to the use of seven phases. The third rotor can be considered as an option of an initial double-rotor axial-flux machine in order to increase the torque density. First, the machine structure and the winding design are presented; then, based on 3D finite element method, comparison between the two machines, with two or three rotors, are provided in terms of torque densities and qualities.

This paper proposes the design and development of a five-phase external rotor permanent magnet synchronous machine (PMSM) which is used for direct drive convey application. Firstly, the slot/pole combination of fraction slot concentrated winding (FSCW) is selected according to four criteria, which are the least common multiple (LCM) and the greatest common divisor (GCD), the winding factor and the MMF distribution; secondly, based on the design requirement, an analytical model of the proposed machine topology is built, and the initial machine parameters are then obtained; thirdly, the machine is optimized by combing the finite element model and the Kriging model, and the final optimal results are compared to the initial one. Detail design principles and performance characteristics of the proposed machine topology are presented and validated with finite element models.

Automotive industry is evolving towards more fault-tolerant actuators to fulfill future autonomous vehicles requirements. Critical applications such as steering or braking have to resist to fault occurrences while being low cost due to mass production market. Considering these two criteria, multiphase electric drives offer a good tradeoff between increasing the degrees of freedom and limiting system oversizing. This paper proposes to compare three multiphase electric drives for electro-hydraulic power steering for trucks: a five-phase machine and a six-phase machine both fed by a full bridge inverter (FBI), and a seven-phase machine fed by a standard half-bridge inverter (HBI). Several comparison criteria are considered in the meantime: motor, electronics, control and manufacturing parameters. Some of criteria are obtained from finite-element analysis (FEA), while others are derived from analytic formula or dynamic simulations. criteria are evaluated for each drive and then results are discussed In the given low-voltage high-current application, H-bridge inverter topology seems to be a promising solution. Both five-phase and six-phase present similar results. However, six-phase drive could be more interesting, as it could be brought close to standard three-phase solutions and adapted to dual-lane supply.

This paper proposes a strategy using new transformation matrices to calculate new current references when a non-sinusoidal seven-phase permanent magnet synchronous machine (PMSM) has an open-circuited phase. The new current references allow to obtain a smooth torque with similar copper losses in the remaining healthy phases even when the back electromotive force (back-EMF) is non-sinusoidal. A real-time current learning process using an adaptive linear neural network (Adaline) is applied to extract from measured currents useful harmonic components in torque generation. It improves torque quality, especially at high speed, even when standard proportional-integral (PI) controllers are applied. In addition, similar copper losses in the remaining phases with the new current references can avoid overheating of windings. The effectiveness of the proposed control strategy is validated by numerical results.

Automotive safety applications will be soon a standard based on market evolution trends. Actuators performing safety operations, such as steering or braking, need to be more reliable with a low manufacturing cost. Multiphase drives seem to be a good alternative to actuators redundancy, as it offers greater degrees of freedom with at a limited extra cost. These drives have been studied for a while, especially in other industries such as ship propulsion or aeronautic actuator. However, comparison between multiphase drives for a given application is rare. In this paper, a methodology is proposed to evaluate several drives for a safety automotive application. Some manufacturing assumptions have been made in order to narrow the study to five, six and seven phase permanent magnet synchronous motors (PMSM). Machines have been modeled using 2-D finite elements analysis (FEA) software in order to extract their parameters which will be used in dynamic simulations. Based on the obtained results, each drive is evaluated according to defined criteria and best solutions are highlighted. Considering a low voltage high current application, full bridge inverter topologies feeding a six-phase motor seem to be a promising solution.

This paper presents a sensorless control strategy for seven-phase non-sinusoidal permanent magnet synchronous machine (NSPMSM) with high frequency signal injection (HFSI) method in 5th harmonic subspace. Seven-phase nonsinusoidal machine benefits high torque density due to the use of third harmonic components. Firstly, two torque generation strategy in different harmonic subspaces with the minimum injected rms value and amplitude of current is deduced in this paper. Secondly, in order to reinforce the reliabilities of multiphase machine, the HFSI sensorless control is employed. Comparing with traditional HFSI method, the proposed control strategy is achieved in 5th harmonic subspace, which can avoid the torque ripple caused by the injected signal. Finally, according to simulations results the two torque distribution method is validated and compared and the effectiveness of the HFSI method is verified.

This paper is to propose a control scheme, a combination of the classical field-oriented control (FOC) technique and artificial intelligence (AI), to obtain constant torques in multiphase non-sinusoidal permanent magnet synchronous machine (PMSM) drives. Higher torque density, easier fabrication, and lower costs are several advantages of non-sinusoidal back electromotive force (back-EMF) machines over sinusoidal ones. However, multi-harmonics existing in back-EMFs possibly generate torque ripples, reducing torque quality of the drive. Therefore, in this paper, an adaptive linear neuron (ADALINE), a simple type of AI, is combined with the classical FOC technique to eliminate these torque ripples. The proposed control scheme is validated by numerical results with a seven-phase PMSM. In addition, these results are compared with an existing strategy to prove its effectiveness.

This paper proposes a new sensorless control strategy based on a Sliding Mode Observer (SMO) for a non-sinusoidal Seven phase PMSMs. This strategy, based on all harmonics contained in the back-EMF, is compared to the classical sensorless control strategy using only the fundamental of back-EMF signal. As the novel sensorless control strategy estimate the rotor position by using different harmonics, it can lead to a good torque response compared to the classical strategy, specially in transient states. Therefore, in order to define the appropriate sensorless control strategy for the non-sinusoidal seven-phase PMSM, each sensorless control strategy will be highlighted in terms of robustness to the speed variation and torque ripple. Simulation results will be shown to verify the feasibility of the proposed methods.

This study is to deal with unwanted current harmonics in rotating (d-q) frames of a 7-phase non-sinusoidal permanent magnet synchronous machine (PMSM) in a wye-connected winding topology. The machine is supplied by a 7-leg voltage source inverter (VSI) fed by a DC-bus voltage. In control, cur-rent responses are expected to properly track their references. However, several unwanted harmonics of the non-sinusoidal back electromotive force (back-EMF) and the inverter nonlinearity generate unwanted harmonic com-ponents in d-q currents. These current harmonics cannot be nullified by con-trollers such as conventional proportional-integral (PI) controllers. Conse-quently, the current responses cannot track their references. In this study, a combination of conventional PI controllers and simple adaptive linear neu-rons (ADALINEs) is proposed to eliminate these current harmonics, improv-ing current control quality of the drive. The effectiveness of the proposed control structure is verified by experimental results.

This study aims at eliminating unwanted harmonics in current control of a five-phase non-sinusoidal permanent magnet synchronous machine (PMSM) in an open-end winding configuration. The machine is supplied by two voltage source inverters (VSIs) using a single DC-bus voltage. High-frequency harmonics, caused by the zero-sequence current with the inverter switching frequency, have been significantly reduced by using a proper pulse width modulation (PWM) strategy. Meanwhile, low-frequency current harmonics are generated by unwanted harmonics of the back electromotive force (back-EMF) and by the inverter nonlinearity. In this study, the low-frequency current harmonics are nullified by simple adaptive linear neural networks (ADALINEs) in rotor reference frames combined with the back-EMF compensation. As a result, the quality of current control is improved. The effectiveness of the proposed strategies is verified by numerical results.

Torque density is usually improved by injecting the third current harmonic for five-phase permanent magnet synchronous machine (PMSM). It increases the degrees of freedom of a multiphase drive. However, it also separates the current limitations of the motor and the transistors, respectively related to the RMS and peak values of the currents. These two constraints are represented by Maximum Torque Per Ampere (MTPA) strategy and Maximum Torque Per Peak Current (MTPPC) strategy. In this paper, these two strategies are studied and analyzed in order to optimize the generated torque with injection of the third current harmonic. Torque improvement principal and the optimizing algorithm considering two constraints are illustrated. Then, the analytical results of these two strategies are compared and discussed. It is shown that injecting the third current harmonic can improve the torque especially at flux-weakening region. Besides, compared with MTPA, MTPPC could produce higher torque for the same inverter current limit.

This paper presents new fault-tolerant control strategies for field-oriented control of 7-phase non-sinusoidal permanent magnet (PM) machines supplied by voltage source inverters (VSI). Single phase open-circuit fault is considered. The proposed strategies aim at finding waveforms of current references in natural frame in the way that post-fault currents create the same rotational magnetomotive force (MMF) as in healthy mode. Therefore, in the faulty mode, average torque can be maintained if no current limits are set. The proposed strategies are validated and compared to a previous strategy by numerical results in terms of joule losses, maximum RMS and peak phase currents, maximum phase voltage as well as their controllability with PI controllers.

This paper presents the modeling and control of an Electric Vehicle (EV) driven by a 5-phase Permanent Magnet Synchronous Machine (PMSM). The machine in an open-end winding configuration is supplied by two isolated 5-leg Voltage Source Inverters (VSIs). The inverters are fed by a Hybrid Energy Storage System (HESS) consisting of a battery and Supercapacitors (SCs). To increase the battery lifetime, the SCs are used to provide the high-power requirement during driving operations. In addition, an Energy Management Strategy (EMS) is proposed to take advantages of this EV architecture. Numerical results are derived to verify workability of the EV system.

For an open-end windings integrated Permanent Magnet Synchronous Machine, the demagnetization of the permanent magnets is analyzed when a transistor is shortcircuited and no specific control strategy is adopted. Depending on the temperature, the high currents due to the inverter fault may locally demagnetized the permanent magnets leading to an accelerated aging of the machine and torque loss. A cosimulation, using a Finite Element software for the machine coupled with an average modeling of the transistor, gives interesting local prediction of the machine behavior in healthy and degraded mode.

Compared to sinusoidal machines, a bi-harmonic machine (with only two harmonics of similar value in the electromotive force spectrum) can develop torque of comparable values under three kinds of supply: with only first or both first and third sinusoidal currents. Therefore, more degrees of freedom for the control of the machine can be achieved. In this paper, the specificities of 7-phase bi-harmonic permanent magnet synchronous machine (PMSM) are investigated under different control strategies, such as maximum torque per ampere (MTPA) at low speed and fluxweakening strategies at high speed, both in healthy and faulty operation modes. The fault with one open-circuited phase are taken into account. The current references are calculated in order to maximize the output torque under the constraint on both voltage and current. The performances of the considered machine is validated by numerical results.

This paper studies control strategies using modified transformation matrices when five-phase machines operate in oneopen-phase faults. The basic idea of these methods is to maintain the rotating field under asymmetrical conditions as the same as in healthy condition by determining new transformation matrices. The dimension of the new matrices is equal to the number of remaining healthy phases in post-fault conditions. There have been different ways to determine the new transformation matrices applied for different types of five-phase machines in recent decades. In this study, an overview and analyses on these methods will be presented. In addition, advantages and drawbacks of these control strategies are clarified by numerical results.

This article presents the development of an algorithm which can be used at standstill and low speed for sensorless control of a five-phase Permanent Manget Synchronous Machines (PMSM) with non-salient poles. The estimation method is based on the machine’s torque. Two different strategies are investigated for the proposed method. The first one uses the torque measurement and the second one uses the estimated torque from the measured currents. Results for the implementation of both strategies are presented and analysed, together with possible improvements to explore.

This paper presents a novel 7-phase hybrid excitation permanent magnet (HEPM) machine with three rotors around one stator. Two rotors with PMs axially magnetized and the third rotor with PMs radially magnetized. Thanks to the addition of the third rotor, the inactive end-windings in the configuration with two rotors are then becoming active with a contribution to the torque with an increase of 30%. The impact of the third rotor on the torque density and on the pulsating torques is presented. The fault-tolerant characteristics of the proposed machine are also presented, which proves the interests of this machine for low speed applications.

This paper deals with control strategies when a seven-phase axial-flux brushless DC machine operates in one open-circuited phase fault by considering constraints on voltage and current. The constraints are related to the converter and machine design in terms of maximum values of voltage and current. In addition, the sensitivity of the torque control on parameters of new imposed current references under the base speed and in the flux-weakening region is analyzed. The current references taking into account only first and third harmonics in healthy phases are proposed to ensure the torque optimization while phase currents and voltages are within their limits. The usefulness of the control strategies and the parameter analyses are verified by numerical results.

A rotor position estimation for low speed and standstill applications in multiphase PMSMs with non-salient poles is presented in this paper. For this purpose, a comprehensive state of the art was performed. Then, an estimation method was proposed based on existing methods for surface three-phase PMSMs, and is finally adapted to a five-phase machine. Experimental results are illustrated and analysed.

In this paper we investigate the impact of the supply strategy on the peak voltage value for a five-phase bi-harmonic machine. In fact, this kind of machine is able to deliver significant equivalent torque from either the first, the third current harmonic due to the equivalent value of these harmonics in the back-emf. Since, different supply strategies are possible for this machine depending on the repartition of current between the two harmonics. Classically, the maximum torque per ampere strategy (MTPA) is used below the base speed, and it is achieved by setting a current in phase with the back-emf, with an optimal repartition of current density between the first and the third harmonic. However, it is not always possible practically to guarantee these features simultaneously, due to uncertainty in control. This uncertainty come out as a phase shift between back-emf and the current, or a modification in the optimal repartition of current density between the first and the third harmonic. Thus, this error can make the required voltage peak value more or less than the maximum voltage that can be delivered by the VSI. FE simulations and experimental are performed in order to test this phenomenon which can determine the sensitivity of the optimal control

This paper deals with the fault effects analysis and diagnosis in 6-Φ PMSM designed for aerospace applications. The addressed work aims to analyze the features offered by the space vector theory applied to these systems for fault detection and identification purposes. The paper starts with a presentation of the overall electric drive system structure and its control. Then, fault effects analysis under faulty operation mode of the 6-leg voltage source inverter is presented considering the space vector theory. Based on such analysis, an accurate FDI process is designed for these applications. All results are verified analytically and through simulation software using Matlab/Simulink

Multiphase machines have recently gained importance in the research community for their use in applications where high power density, wide speed range and fault-tolerant capabilities are needed. The optimal control of such drives requires to consider voltage and current constraints imposed by the power converter and the machine itself. If classical three-phase drives have been optimally controlled under such limits for a long time, the same cannot be said in the case of multiphase drives. This paper deals with this issue, where an optimal control technique based on Cascaded Model Predictive Controls (MPC) is presented for a five-phase permanent magnet synchronous machine (PMSM). A Continuous-Control-Set MPC (CCS-MPC) numerically computes optimal current references in real-time in order to exploit the maximum performance for given DC bus voltage and current limits. Then, a Finite-Control-Set MPC (FCS-MPC) is used to carry out the current control in the machine, directly applying the switching state that minimizes a cost function related to the current tracking. Obtained mixed microprocessor-based and FPGA-based real-time simulations prove the interest of the proposal, which ensures the optimal control of the multiphase drive operating under current and voltage constraints.

This papers presents a sensorless control for fivephase PM synchronous machines. An adaptive method, based on a linear neural network called Adaline (Adaptive Linear Neural Networks), has been achieved to estimate the rotor position with a high precision even at low speed without high frequency signal injection. Non-sinusoidal three-phase PM machines require more complex algorithm for sensorless control because of harmonics in the back-EMF. This is not the case for multiphase PM machines thanks to the property of equivalent machines in the eigenspace. Some given simulation and experimental results in laboratory confirm the possibility of real-time implementation of Adaline networks and the good performance of sensorless control based on this.

This paper deals with the real time Fault Detection and Identification (FDI) process of inverter Open Switch Fault (OSF) and Open Phase Fault (OPF) in five-phase PMSM designed for aerospace applications in which the electric drive system has particular operating characteristics either in healthy states or in the faulty ones. Two original contributions are considered in this paper. They consist in normalizing the input variables of the FDI process applied to multiphase system and compensating the noise (switching and sensors noises) and dc-component resulting from the fault occurrence. The proposed strategy uses multiple normalized criterias derived from the measured phase currents and the voltages obtained from the outputs of the current controllers. The FDI shows an independence with respect to the transient states and to the switching and measurement noises. Moreover, it can be easily included in an existing software without any additional sensors. The validity of the proposed method is verified by Matlab/Simulink simulation tests.

This paper describes analytical and simulation tools to analyze the effects of Open Switch Fault (OSF) and Open Phase Fault (OPF) on five-phase PMSM designed for aerospace applications. For such applications, the fault tolerance and the reliability of the drive (PMSM and the power converter) are important to take into account for design. The addressed work aims essentially to analyze the dynamic of the measured phase currents in post-fault operation with a real-time fault diagnostic purpose in the VSI. The paper starts with a presentation of the electric drive system structure and its control used in pre-fault and post-fault operation. Then, fault effects analysis (FEA) on the system will be considered. All results are verified analytically and through simulation software using Matlab/Simulink®. The theoretical development and the simulation results show that the five-phase PMSM under inverter faults presents typical characteristics which can be used as better input variables for designing a high performance real-time fault diagnostic and classification process

This paper presents a new idea by using the Artificial Neural Networks (ANNs) for estimating the parameters of the machine which achieving the maximum efficiency of the Synchronous Reluctance Motor (SynRM). This model take into consideration the magnetic saturation, cross-coupling and iron loss. With Finite Element Analysis (FEA), the characteristics of the SynRM including inductances and iron loss resistance are determined. Because of the non-linear characteristics, an ANN trained off-line, is then proposed to obtain the d-q inductances and iron loss resistance from Id,Iq currents and the speed. After learning process, an analytical expression of the optimal currents is given thanks to Lagrange optimization. Therefore, the optimal currents will be obtained online in real time. This method can be achieved with maximum efficiency and high-precision torque control. Simulation and experimental results are presented to confirm the validity of the proposed method.

This paper analyzes two dual-motor fault-tolerant topologies. The first one supplies independently both machines while the second one connects them in series for reducing the number of transistors. For a given DC-link voltage, the converter component sizing is based on the peak current obtained in the normal and degraded modes.

This paper analyzes two dual-motor fault-tolerant topologies for aerospace thruster application.The first structure supplies independently both machines whilethe second one connects them in seriesfor reducing the number of transistors and offering a capability of energy management between the sources. Inverter short-circuit fault isconsidered.Based on the peak-currents obtained in simulation in degraded mode without reconfiguration and with two different reconfiguration strategies, the two proposed topologies can be compared in economic and technical aspects.

The optimal control of electrical drives necessitates to take into account current and voltage limits that are imposed by the power electronics and the electrical machines. Let’s cite for example the flux-weakening operation of electrical drives or propulsion. If the control of classical three-phase drives under voltage and current limits are known for a long time, the specific characteristics of multiphase drives open the way to researches on their control under such constraints. This paper aims to explain what are the main differences between three-phase and multiphase drives when they run under voltage and current constraints and try to show what are the scientific and technical problems to be solved. Some first results are given in order to show that Model Predictive Control (MPC) is expected to be a good candidate to answer the proposed challenge.

An original analytical expression is presented in this paper to obtain optimal currents minimizing the copper losses of a multi-phase Permanent Magnet Synchronous Motor (PMSM) under fault conditions. Based on the existing solutions [i]opt1 (without zero sequence of current constraint) and [i]opt2 (with zero sequence constraint), this new expression of currents [i]opt3 is obtained by means of a geometrical representation and can be applied to open-circuit, defect of current regulation, current saturation and machine phase short-circuit fault. Simulation results are presented to validate the proposed approach.

The work presented in this paper aims to propose a control strategy being able to extract efficiently energy from a fixed-pitch marine current turbine associated with a 5–phase Permanent Magnet Synchronous Generator (PMSG) in healthy mode and in faulty mode. The considered faults are opened phases. For each tidal current speed, the control strategy aims to extract the maximum power with respect of the maximum values of currents and voltages related to the converter. The maximum power is directly related to the Maximum Torque per Ampere (MTPA) control strategy characteristics (all the points which are below the MTPA torque VS rotating speed characteristic can be reached by the converter/generator set). This paper proposes a methodology to establish MTPA characteristics and calculate the corresponding current references in healthy mode and in faulty mode (one or two opened phases) for a 5-phase generator. The studied strategy includes flux weakening operations in the both modes.

All-electric vehicles should be made more reliable in such way one can continue driving even after the event of one or more faults in the electrical drive. For this, the use of multiphase (more than 3 phases) electrical machines is considered here due to its redundant feature. An additional technique to increase reliability is to replace sensors by observers. This paper studies the feasibility to control the torque in multi-phase permanent magnet synchronous drives without a position sensor, with the lowest Joule losses, and this for a healthy as well as for a faulty operation with one or more phases open-circuited.

Multi-phase machines are known for their fault-tolerant capability. However, star-connected machines have no fault tolerance to inverter switch short-circuit fault. This paper investigates the fault-tolerant operation of an open-end five-phase drive, i.e. a multi-phase machine fed with a dual-inverter supply. Open-circuit faults and inverter switch short-circuit faults are considered and handled with various degrees of reconfiguration. Theoretical developments and experimental results validate the proposed strategies.

This paper presents a new method based on Artificial Neural Networks to obtain the optimal currents, for reducing the torque ripple in a Non-sinusoidal Synchronous Reluctance Motor. Optimal current control has to develop a constant electromagnetic torque and minimize the ohmic losses. In d-q reference frame without homopolar current, the direct and quadrature optimal currents will be determined thank to Lagrange optimization. A neural control scheme is then proposed as an adaptive solution to derive the optimal stator currents. Thank to learning capacity of neural networks, the optimal currents will be obtained online. With this neural control, either machine’s parameters estimation errors or current controller errors can be compensated. Simulation results using Matlab/Simulink are presented to confirm the validity of the proposed method.

This paper presents a specific control strategy of double-ended inverter system for wide-speed range of open-winding five phase PM machines. Different virtual stator winding configurations (star, pentagon, and pentacle) can be obtained by choosing the appropriated switching sequences of two inverters. The motor’s speed range is thus increased.

This paper proposes a sensorless control based on Sliding Mode Observer (SMO) for a Five-phase Interior Permanent Magnet Synchronous Machine (FIPMSM), with a consideration of the third harmonic component. Compared to the conventional three-phase machines, the third harmonic of electromotive force contains more information. Thus, in this paper, we consider the first and third harmonic components of the five-phase machine to estimate the rotor position that is necessary for the control. Simulation results of the implemented SMO are shown to verify the feasibility of the proposed sensorless control strategy

Dans le cadre d’une commande en mode dégradé d’un drive comprenant deux machines polyphasées connectées en série et pilotées de façon indépendantes, l’article s’intéresse à analyser la performance du drive dans le cas d’une reconfiguration complète, c’est-à-dire, une modification de l’algorithme de commande lors d’un défaut en mode dégradé

Cet article s’intéresse au dimensionnement de génératrices synchrones polyphasées à aimants permanents destinées à être associées à un multiplicateur de vitesse de faible rapport (qui ne nécessite que très peu d’entretien contrairement au multiplicateurs de rapports élevés) et une turbine à pas fixe. L’objectif est de comparer les structures à bobinage concentré à 5 phases régulièrement réparties et les structures à 2*3 phases, à une structure de référence à 2*3 phases à bobinage distribué classique, afin de voir l’influence du bobinage et de la structure polyphasées choisies, en termes de capacité de fonctionnement en défluxage en mode normal et dégradé pour un même cahier des charges relatif à une génératrice hydrolienne.

This paper presents an original method, based on artificial neural networks, to reduce the torque ripple in a permanent-magnet non-sinusoidal synchronous motor. Solutions for calculating optimal currents are deduced from geometrical considerations and without a calculation step which is generally based on the Lagrange optimization. These optimal currents are obtained from two hyperplanes. The study takes into account the presence of harmonics in the back-EMF and the cogging torque. New control schemes are thus proposed to derive the optimal stator currents giving exactly the desired electromagnetic torque (or speed) and minimizing the ohmic losses. Either the torque or the speed control scheme, both integrate two neural blocks, one dedicated for optimal currents calculation and the other to ensure the generation of these currents via a voltage source inverter. Simulation and experimental results from a laboratory prototype are shown to confirm the validity of the proposed neural approach.

In this paper, a multiplexing technique is applied on a neural harmonics extraction method, based on an efficient formulation of the instantaneous reactive power theory. This approach can be used in nonlinear loads compensation with APFs (Active Power Filters). The architecture for reference current generation, synchronized by a neural phase lock-loop, is composed of three Adaline neural networks. This leads to an important consumption of field programmable gate array resources during implementation. The proposed technique uses only one Adaline and keeps the immunity of the approach under non-sinusoidal and unbalanced conditions of voltage. Simulation results of the neural harmonics detection system connected to a reference current controller show balanced and sinusoidal source currents under various conditions. Results with experimental measurement made on an APF test bench demonstrate its good performances on harmonics filtering. Moreover, the simplified structure from the new approach called mp-q method shows a significant resource reduction.