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LABORATOIRE D'ELECTROTECHNIQUE ET D'ELECTRONIQUE DE PUISSANCE DE LILLE

Recherche, Développement et Innovation en Génie Electrique

Seminar in OMN TEAM

The research team OMN works on different numerical methods associated to electromagnetic field computation. We organize the Junior Seminar in LILLIAD Learning center innovation by our Ph.D. students, as well as our postdocs, and Invited Seminar by the external researchers.

If you would like to give us a talk or have some collaboration ideas about our work, please contact Zuqi who is in charge of the seminar, we can invite you to Lille.
The seminar can be held in English (or French) as you like. There is no limit for the duration of the seminar.

Seminars between Ph.D Student:

More details

  

Upcoming seminars:

TBA on December, 2019, Invited Seminar

Schedule

Olga MULA (Paris Dauphine University): TBA


 

 

TBA on September, 2019, Invited Seminar

Schedule

Stéphane CLENET: TBA


 

 

TBA on September, 2019, Invited Seminar

Schedule

Zuqi TANG: TBA


 

 

July 8, 2019 at 14h00, Invited Seminar


Pr. Stéphane CLENET (ENSAM)

Stéphane Clénet is full professor of electrical engineering at Ecole Nationale Supérieure d’Arts et Métiers (ENSAM), France. After the completion of his PhD, he was Associate Professor at the University of Lille in 1994 before being appointed as full professor in 2002 at ENSAM. In 2008, he was visiting professor as Fulbright Grantee at the University of Akron (USA) in 2008 and 2014 and at Mc Gill University (Canada) in 2015. From 2007 to 2014, he ran a research team in the field of computational electromagnetics and its applications involving more than 25 professors, post docs and PhD students. From 2016 to 2019, he was the director of the campus ENSAM of Lille. He works on the development of 3D Finite Element Model in low frequency. Since 2004, his research focuses mainly on uncertainty quantification in computational electromagnetics based on stochastic approaches and also on Model Order Reduction technics (POD, PGD…). He is co-author of 85 publications in international journals. He has collaborated with numerous researchers from different universities in France but also from abroad like in Liège (Belgium), Akron (USA), Santa Catarina (Brésil), Mc Gill and Laval (Canada), Aalto (Finland), Tsinghua (China), Aachen (Germany). He develops numerous research projects in partnership with major companies like EdF, Valeo, CEA.

Why and how uncertain quantification can be useful in low frequency electromagnetism?

In some applications represented by very accurate models (the modelling and the numerical errors are negligible), if a gap exists between the measurements, assuming perfect, and the results given by the numerical model, it comes from deviations on input parameters which are not in the ”real world” equal to their prescribed values.
The origins of these deviations are numerous and are related to either a lack of knowledge or uncontrolled variations of quantities like temperature, pressure, magnetization. To account for these uncertain deviations on model parameters, the stochastic approach can be used. The model parameters as well as the outputs are then random fields or variables. Several methods are available in the literature to solve stochastic models like sampling methods, perturbation methods or approximation methods. In this presentation, we propose an overview on the solution of stochastic problems in computational electromagnetics. Some applications will be presented in order to illustrate the possibilities offered by this approach Finally, recent numerical techniques proposed in the literature to alleviate the cumbersome needs of resources in terms of memory and time calculation of the stochastic approach particularly due to the the curse of dimensionality appearing when the number of uncertain parameters increases.


 

 

June 27, 2019, Invited Seminar (Invited Prof. of ULille)

Dr. Shuai YAN (Institute of Electrical Engineering, Chinese Academy of Science)

Shuai Yan received the B.S. degree in Mathematics and Applied Mathematics from Beijing Normal University in 2007 and the M.S. degree in Computational Mathematic also from Beijing Normal University in 2010. She received the Ph.D. degree in Computational Optics in University of Erlangen-Nuremberg in Germany, 2014. After that, she joined the Chinese Academy of Science as an Associated Researcher. She has published more than ten papers in international journals. Her current research interests are model reduction techniques for full wave analysis and optimization of high frequency RFID systems and also efficient solvers for multi-physics analysis in integrated circuit design.

Title: Model Order Reduction with POD/PGD and Related Applications in Computational Electromagnetics

Modern industrial development brings new challenges to computational electromagnetics by introducing extremely computationally intensive problems and the needs of real-time simulation. Model order reduction can help with tacking these challenges from two perspectives. One is to solve the problems with less computational cost in time and memory, another is to build a compact parametric model from an “offline process” which can be used to achieve a fast solution during an “online process”. POD and PGD are two important MOR techniques that attracts much attention in recent years. In this presentation, I will discuss about the implementation of POD and PGD in both static and high frequency problems. Issues including complex domains, high dimensionality as well as adaptive algorithms will be addressed.


 

 

June 13, 2019, Junior Seminar


Dr. Emna JAIEM

Emna Jaïem obtained a PhD degree in Applied Mathematics from Tunis El Manar University, Tunis, Tunisia in July 2016. During her PhD thesis, she investigated the geometrical inverse problem related to the identification of defects in mechanical structures from, on the one hand, overdetermined boundary data and, on the other hand sub-Cauchy data. Indeed, her research fields include shape optimization (shape derivative, topological derivative, level set method, …). In September 2017, her work was recognized with the TWMA (Tunisian Women Mathematicians’ Association) award for the best PhD thesis in Applied Mathematics for Tunisian women. She is currently a postdoctoral researcher at L2EP working on the numerical analysis of electromagnetic fields and more precisely on spectral methods (Harmonic Balance Method).

Harmonic balance finite element method applied to electromagnetic problems

The time stepping approach is a well-known numerical method to model electromagnetic problems. However, it can present some drawbacks since it requires expensive computation time in the case of a large transient state. To overcome this problem, harmonic balance method can be used. In the first part of the presentation, we introduce this method. Then, we apply it for electrical machines taking into account the motion. Furthermore, we compare the solutions obtained by the harmonic balance finite element method coupled, on the one hand, with the A formulation and, on the other hand, with Ω formulation with those obtained by the reference method; namely the time stepping finite element method.

Since harmonic balance method relies on the representation of time-periodic function by a truncated Fourier series, the problem of harmonics selection is discussed in the second part of the presentation. A novel approach based on time residual is proposed to solve a nonlinear magnetostatic problem using harmonic balance method.


 

 

June 07, 2019, Invited Seminar


Pr. Mircea M. RADULESCU (Université Technique de Cluj-Napoca, Roumanie)

Mircea M. Radulescu received the Dipl.-Ing. degree in electrical engineering (with honors) from the Technical University of Cluj-Napoca, Cluj-Napoca, Romania, in 1978, and the Ph.D. degree in electrical engineering from the Polytechnic University of Timisoara, Timisoara, Romania, in 1993. Since 1983, he has been with the Faculty of Electrical Engineering, Technical University of Cluj-Napoca, where he is currently a Full Professor in the Department of Electric Machines and Drives, and Head of the Special Electric Machines and Light Electric Traction (SEMLET) Research Laboratory.
He is the author or co-author of more than 180 published scientific papers in refereed technical journals and international conference and symposium proceedings.
His teaching and research activities include classical and special electric machines; computer-aided design of electromechanical devices; design and control of small electronically-commutated motors; actuators and mechatronic drives; light electric traction systems; design and analysis of small-scale renewable energy equipment.
He was an Invited Professor at Swiss Federal Institute of Technology Lausanne – EPFL, Switzerland; Helsinki University of Technology, Espoo, Finland; RWTH Aachen, Aachen, Germany; University of Akron, Akron, USA; University ‘Pierre et Marie Curie’, Paris, France; University of Picardie ‘Jules Verne’, Amiens, France, and Centrale Lille,
Villeneuve d’Ascq, France.
He is an Associate Editor of the international scientific quarterly ‘Electromotion’. His biography is listed in several editions of ‘Who’s Who in the World’ and ‘Who’s Who in Science and Engineering’.
Prof. Radulescu is a Senior Member of IEEE, USA and a Member of IET, UK. He is also a member of the International Steering Committees of several conferences and symposia in the field of electric motor drives, electric traction, and renewable energy.

Nouvelles topologies de générateurs électriques pour micro-éoliennes

Contenu

Introduction aux éoliennes à petite échelle
Exigences de conception des générateurs électriques pour les micro-systèmes de conversion d’énergie éolienne
Analyse comparative de la conception des nouvelles topologies des micro-aérogénérateurs électriques
Conclusion


 

 

June 04, 2019, Visiting Professor from Shanghai Maritime University


Dr. Hao CHEN (Shanghai Maritime University, China)

Hao Chen (M’ 17) was born in Jiangsu, China, in 1985. He received the B.E. degree in automation from Shanghai Maritime University, Shanghai, China, the M.E. and Ph.D. degrees in electrical engineering from the University of Nantes, Nantes, France, in 2008, 2010, and 2014, respectively. He is currently a lecture with Shanghai Maritime University China. His research interests include designing, modeling and control of electrical machines, and wind or tidal energy conversion system.

Research on power electronics and electric drives at Shanghai Maritime University

In the presentation, I firstly introduce Shanghai Maritime University and the colleges briefly. Then, I will focus on the introduction of the department of electrical engineering, especially the research institute of power drive and control. At last, I will present some personal research interests.


 

 

Past seminars:

December 06, 2018, Invited Seminar

Pr. Jiaxin YUAN (Wuhan University)

Jiaxin Yuan (M’07) was born in Nanchang, China, on June 10, 1981. He received the B.S. and Ph.D. degrees from the School of Electrical Engineering, Wuhan University, Wuhan, China, in 2002 and 2007, respectively. From 2007 to 2009, he was a Lecturer with Wuhan University, where he was engaged in research and development of STATCOM and DSP inverter control and, since 2007, he has been engaged in power electronics system control, power quality issues, and application and control of inverters. From 2016, he got the full Professor position at the School of Electrical Engineering, Wuhan University.

The Present Status and Future of Fault Current Limiter in High Voltage Power System

The first part of the presentation gives some brief introduction to Wuhan University, as well as the Department of Electrical Engineering and Automation.
The second part will introduce the Present Status and Future of Fault Current Limiter in High Voltage Power System. Nowadays, the short circuit fault current increasing rapidly in all of the worlds. The short circuit fault current in some grid exceeds the capacity of the breaker, seriously threatening the safety and stability of the power grid. So the presentation will explain the principle of rapid increase in the short circuit current, analysis the different methods to reduce the short circuit current. At last, the presentation will propose a novel fault current limiter.


 

November 29, 2018, Invited Seminar

="" Dr. Alain BOSSAVIT

Sur l’approche géométrique des équations de Maxwell et de leur discrétisation


 

Nomember 20, 2018, LAMEL Day(Plénière du LAMEL)

Schedule

10h00-10h30 : Kévin DARQUES : Modélisation de la tension d’arbre
10h30-11h00 : Sylvain SIHAB : Modèles de pertes magnétiques
11h00-11h30 : Rihad CHERIF : Solveurs Non linéaire
11h30-12h00 : Loic Chevallier et Juien KORECKI : Code_carmel

14h00-14h30 : Emna JAIEM : Mouvement pour Méthode Spectrale
14h30-15h00 : Lydéric DEBUSSCHERE : Techniques de remaillage
15h00-15h30 : Guillaume CARON : Réduction de modèles

 

November 09, 2018, Invited Seminar

="" Oualid MESSAL

Oualid Messal received the Ph.D. degree in Electrical Engennering from Lyon University in Dec. 2013. From 2013 to 2014, he was a Temporary Assistant Professor of Electrical and Computer Engineering with Lyon1 University. From Sep. 2014 to Aug. 2018, he was a CNRS postdoc researcher at the Grenoble Electrical Engennering Laboratory. During his thesis and postdoc, he has been the principal investigator on a number of successful research programs including Aperam company, Renault, Altair, Schneider Electric, etc.
The primary focus of his investigations is the area of magnetic materials for electrical engineering applications. From Sep. 2018, he is associate professor at Lille University where conducts research at the Lab of Electrical Engineering and Power Electronics.

Characterization and modeling of soft magnetic materials for electromagnetic applications


 

September 14, 2018, Visiting Professor from Xi’an Jiaotong University


Pr. Shuhong WANG (Xi’an Jiaotong University)

Prof. Shuhong Wang was born in China, in 1968. He received his Ph.D. degree in Electrical Engineering from Xi’an Jiaotong University, in 2002. Currently, he is a Professor with School of Electrical Engineering, Xi’an Jiaotong University. He is a senior member of IEEE (No. 92041995) and a board member of Council of Applied Superconducting Technology of China Electrotechnical Society. His research interests include theory, computation and application of electromagnetic fields and design, simulation and optimization of electrical apparatus. He presided one National Science and Technology Major Project, two projects supported by the National Natural Science Foundation of China and tens of projects supported by electric power company. He is the author of more than 100 technical papers as well as 6 professional books.

Research on short circuit dynamic characteristics and mechanical life of power transformer winding (Ph.D. student: Shuang WANG)

The dynamic characteristics of transformer windings under short circuit state are of great significance to the safe operation of transformers. The electromagnetic properties of a 110 kV transformer, including leakage magnetic field and electromagnetic force of windings, are calculated using finite element method (FEM). During the short circuit, the power transformer windings’ dynamic force, displacement and stress are calculated. The characteristics of windings’ dynamic motion process because of the big electromagnetic force are analyzed. The mechanical life model of transformer windings is established based on the mechanical experiment of the winding material. The analysis method and research results can provide reference for taking measures to enhance the ability to withstand short circuit of transformer windings.

Study on the Electromagnetic Field in HVDC/AC Hybrid Submarine Cable Tunnel (Ph.D. student: Ting ZHU)

There is a rapidly increasing on the volume of HVDC cable over the last twenty years. To reduce the cost of cable tunnel construction, it is very common that the HVDC cable is laid in the original alternating current (AC) cable tunnel. In the Xiang’an tunnel of Xiamen, China, the operation and maintenance personnel have an electric shock when contacting the sandboxes in DC side during the work period. A model of the tunnel with ±320kV DC cable lines and a 220kV AC cable line is shown in this presentation. The distribution of power frequency electromagnetic field in the HVDC/AC hybrid submarine cable tunnel is studied by simulation and measurement, and the cause of the accident that the operation and maintenance personnel have an electric shock in the tunnel is analyzed, which provides guidance for the safe operation of the cable.

Visiting Schedule

09h40-10h00: Welcome coffee
10h00-10h30: Presentation of L2EP Laboratory and of “OMN” Team
10h30-11h00: Research on short circuit dynamic characteristics and mechanical life of power transformer winding
11h00-11h30: Study on the Electromagnetic Field in HVDC/AC Hybrid Submarine Cable Tunnel

14h00-14h30: Magnetic materials characterization
14h30-15h00: Visiting Platform – Magnetic Materials
15h00-16h00: Discussions / exchanges on potential collaboration projects

 

September 4, 2018, Visiting Professor from Zhejiang University


Pr. Shiyou YANG (Zhejiang University)

Shiyou Yang has been a full Professor at the College of Electrical Engineering, Zhejiang University since 2001. Currently, his research interests include computational Electromagnetics in both high and low frequency domains, the application of numerical techniques in electronic and electromagnetic devices. He has worked in the Department of Electrical and Computer Engineering, Duke University, USA, from November 2007 to May 2008 as a visiting scholar; the Department of Electrical Engineering, the Hong Kong Polytechnic University, Hong Kong, as a postdoctoral research fellow, research and senior research fellows from periods of September 2006 to February 2007, September 2005 to November 2005, March 2003 to February 2004, September 1999 to August 2001; Sau Paulo State University, Brazil, from September 1998 to August 1999 as a postdoctoral research fellow; and Université Pierre et Marie Curie, France, from September 9, 2017 to October 8, 2017 as a visiting Professor. So far, he has published more than 150 papers in referred international conference and journals, and more than 100 in high rank international journals.

Visiting Schedule

13:15 – 13:30 Presentation of “OMN” Team
13:30 – 13:45 Presentation of EEA department
13:45 – 14:00 Presentation of L2EP Laboratory
14:00 – 14:15 Presentation of “Control” Team
14:15 – 14:30 Model order reduction
14:30 – 14:45 Sophemis Optimization Platform
15:00 – 15:20 Visiting Platform – Electrical Vehicle
15:20 – 15:40 Visiting Platform – Power Electronics
15:40 – 16:00 Visiting Platform – Materials

 

August 31, 2018, Invited Seminar

Pr. Chijie ZHUANG (Tsinghua University)

Chijie Zhuang received the B.Eng. and Ph.D. degrees from the Department of Electrical Engineering, Tsinghua University, Beijing, China, in 2006 and 2011, respectively. After a 2-year post-doc program, he became an assistant professor in Tsinghua University, where he was promoted to be an associate professor in 2015. His research interest includes air gap discharge and lightning protection, as well as numerical simulations for problems in electrical engineering.
He has published about 30 papers in international peer-reviewed journals. He was the secretory of CIGRE C4.26 working group (WG), and is the secretory of C4.45 WG, a member of IEEE P2426 WG. He also serves as an associate editor of High Voltage published by IET and CSEE Journal of Power and Energy Systems published by IEEE.

Electrical Discharges: Experiment and Simulations——Two Examples

A leader is an electric discharge mechanism in long-air-gap discharges, which is generally described by a set of convection-diffusion equations, Poisson’s equation and Navier-Stokes equations. We report the shockwave phenomenon in an air-gap leader discharge observed using a Mach-Zehnder interferometer with a time resolution of several microseconds. The continuous temporal evolution of the shock wave and the plasma channel was recorded and reproduced with a thermo-hydrodynamic model discretized by MUSCL and TVDRK schemes, with the measured current as the model input. The simulation results for the shock wave front positions and the plasma channel radius showed good consistency with the experimental measurements. Detailed thermal parameters obtained through the simulation showed that continuous energy injection by the current results in a temporary over-pressure process in the plasma channel and produces the shock wave.

 

July 2, 2018, Invited Seminar

Pr. Anouar BELAHCEN (Aalto University)

Anouar Belahcen (M’13-SM’15) received the M.Sc. (Tech.) and Doctor (Tech.) degrees from Helsinki University of Technology, Finland, in 1998, and 2004, respectively. He is now Professor of Energy and Power at Aalto University, Finland and Visiting Professor of electrical machines at Tallinn University of Technology, Estonia. His research interest are numerical modelling of electrical machines, magnetic materials, coupled magnetomechanical problems, magnetic forces, magnetostriction, and fault diagnostics of electrical machines.

Research at Aalto University, with an emphasis on the magnetomechanical coupling

The first part of the presentation introduces some of the research subjects at Aalto University, Department of Electrical Engineering and Automation. The second part focuses on the research related to the magnetomechanical coupling in electrical steel. Here a measurement setup for rotational magnetic field and arbitrary mechanical stress will be presented together with the results of measurements on a non-oriented electrical sheet. Further, a model for the magnetomechanical coupling will be presented and discussed. The magnetic properties of electrical steel sheets are known to be highly stress dependent. During the manufacturing processes and operation of these devices, multi-axial stresses are exerted on the core laminations. The performance of the electrical machines is then significantly affected by these multi-axial loadings. In order to be able to design efficient devices and analyze the existing ones with better accuracy, the dependency of the core losses on the multi-axial stresses should be studied comprehensively. Yet another important issue is the effect of these loading on the noise and vibrations of electrical machines.

 

 

Juin 21, 2018, Junior Seminar

Reda EL BECHARI

Reda El Bechari was born in Taza, Morocco, in 1993. He received his Master degree from ENSAM Lille, in 2016. Jointly, he has got an engineering degree (Industrial Engineering) from ENSAM Casablanca, Morocco.
He is currently a Ph.D. student with L2EP in Centrale Lille. His research fields include numerical methods of electromagnetic fields, robust design and reliability based design optimization for electromagnetic devices.

Approaches to Design Optimization of Electromagnetic Devices using Finite Element Method

The increasing constraints on the design of electromagnetic devices require numerical tools that are able to finely model the electromagnetic fields in the studied domain. Finite Element Method (FEM) is the most used tool to satisfy such a requirement. However, it may turn out that this tool is very expensive in computational time due to nonlinear behavior, 3D geometries, and time dependency. Thus, its usage for optimization, i.e. iterative process, should be made with caution since only a limited number of evaluations of the simulation tool are possible. Thus, the use of some specific algorithms may not be possible in a limited time, e.g. genetic algorithms, that require many evaluations of the FEM code. On the other hand, gradient-based algorithms cannot be used to their full potential due to the re-meshing error that may appear when computing the gradient using finite difference.
There exist two approaches. A non-intrusive approach that considers the FEM simulation as a black-box and constructs cheap meta-models to reduce the computational burden while refining only in promising regions. And a second approach aims to exploit the derivative of quantities of interest computed from the finite element code by using the adjoint method to be able to use gradient-based algorithms.

 

Juin 1, 2018, Junior Seminar

Kévin DARQUES

Kévin Darques was born in Neufchâteau, Vosges, France in 1990. He received his Master of Electrical Engineering from Lorraine University in 2014. During is degree, he had the opportunity to work with the Jeumont Electric company to study the permanent magnet losses in electrical machines with concentrated windings. After that, he started a Ph.D. at the University of Lille and EDF R&D (CIFRE). His work focused on the analysis of the shaft voltage of high-power turbogenerators. His research topic focuses toward His research topic focuses toward the finite element analysis of electrical machines.

Contribution to the shaft voltage modeling of high-power generators

In large turbo-generators, shaft voltage exists due to the inherent minor imperfections in the construction of the machine or material imperfections but also to defects such as eccentricities or rotor shorts circuits. Therefore, its analysis can constitute a variable to be used to diagnosis some machine defects. A first step consists in determining in an accurate way the effect of these defects on the shaft voltage. In this aim, a didactic analysis is carried out with the help of numerical model based on 2D FEM.
Two high-power non-salient pole synchronous generators of 2 and 4 poles are studied. The study is carried out gradually, first on a simplified structure and then introducing the effect of the stator slots, the parallel coupling, the load or eddy currents in the damper bars have been investigated. The obtained results are analysed in order to clearly determine the impact of each variable.

 

May 23, 2018, Invited Seminar

Antonio Wendell de Oliveira Rodrigues (IFCE)

Antonio Wendell de Oliveira Rodrigues a soutenu une thèse de l’Université des Sciences et Technologies de Lille (France) sur un sujet relatif à l’informatique haute performance utilisant les GPU avec une approche IDM pour la simulation des machines électriques, cofinancée par le Ministère de l’Éducation Française et la société VALEO. Il a fait un stage postdoctoral en gestion de l’innovation au Collège Lambton (Canada) et est titulaire d’un diplôme en ingénierie électrique avec spécialisation en informatique de l’Université Fédérale de Ceará. Enseignant-chercheur à l’IFCE (Brésil) dans les domaines de recherche suivants : ingénierie logicielle, calcul haute performance, réseaux informatiques et systèmes distribués. Il travaille dans divers projets de RD&I en utilisant le traitement d’images pour l’identification des patterns, l’utilisation de drones pour l’inspection par imagerie thermique, SmartGrid, IoT, l’apprentissage de machine…

RD&I et projets appliqués au secteur électrique au Brésil

Antonio Wendell de Oliveira Rodrigues nous fera un panorama des projets de RD&I pour le secteur de la génération, la transmission et la distribution d’énergie au Brésil via une approche calcul scientifique, basée sur des techniques de traitement d’images pour la reconnaissance d’objets, le calcul haute performance, l’intelligence artificielle, IoT et autres.

 

April 26, 2018, Invited Seminar

Brijesh Upadhaya (Aalto University)

Brijesh Upadhaya was born in a small town of Saptari district, Nepal, in 1986. He received his Bachelor of Engineering (Electrical Engineering) degree from Kathmandu University, in 2008. After receiving the B.Eng. degree he joined the alternative energy promotion center (AEPC, Ministry of Environment), and worked as a technical officer for the rural energy development program in the hilly and mountaineous districts of Nepal. In year 2010 he participated for the Fredkorpset Norway (:fK) south-south exchange program as an electrical engineer for the development of the micro-hydro power, in Laos. During his assignment in Laos he was hosted by the Sunlabob Renewable Energy Ltd. Brijesh had an opportunity to work for the energy demand forcast in southern Laos, detail feasibility study of the micro and pico hydro systems in Northern Laos, design of the solar home systems for the projects in Cambodia and Marshall Islands. After completion of the project in Laos, Brijesh started his Master of Science degree in electrical engineering at Aalto University, Finland, in 2012. He received his M.Sc. (Tech) degree in 2014 with a major in electrical systems and minor in electrical drives. Brijesh enrolled as a doctoral student in the research group of electromechanics at the Aalto University and he is currently working towards his doctor of science degree in electrical engineering. His research topic focuses toward the development of a vector hysteresis model that take into account the magnetic anisotropy. The anisotropic model should be suitable for the magnetic field analysis of the mangetic devices.

Modeling of the magnetic anisotropy in a soft magnetic material

A non-oriented (NO) electrical steel sheet present a certain level of magnetic anisotropy. Unlike a grain oriented (GO) electrical steel, the degree of magnetic anisotropy found in the NO electrical steels vary considerably, between low-to-medium levels. A large percentage of the electrical applications utilize the NO electrical steel sheet, such as the rotating electrical machines. Thus, for an efficent design of the electrical applications, an accurate magnetic material model have become increasingly important. For this reason, the magnetic material model capable of describing a weakly anisotropic NO electrical steel sample has been studied in this work. This studied model is an extension of the phenomenological Jiles-Atherton hysteresis model. Furthermore, the extended model of the magnetic anisotropy is analysized, and the simulation results from this model has been compared with the measured magnetic charecteristic. Moreover, the numerical challanges has been studied, regarding the implementation of the vector Jiles-Atherton hysteresis model in a 2D finite element analysis.

 

April 20, 2018, (C2EI Day)

Schedule

Moustafa AL EIT : « Exploitation of the geometrical periodicity of electrical machines in the FE modeling »

Jian ZHANG : « modeling and experiment validation of squirrel cage asynchronous machine with and without faults »

Emna JAIEM : « Spectral finite element method to solve magnetostatic problem taking into account the movement »

 

 

April 19, 2018, Junior Seminar

Sylvain SHIHAB

Sylvain Shihab receive his Master and Phd in condensated matter physics at the Pierre and Marie Curie University in 2012 and 2015. He worked mainly on the magnetization dynamics in the diluted magnetic semiconductor (Ga,Mn)(As,P). He is currently research engineer at the L2EP laboratory. His main researches are on the study and the characterization of soft magnetic steel alloys used in electrical machine to improve models describing magnetization behavior law.

Characterization and modeling of magnetic steels alloys used in electrical machines

Magnetic materials are the heart of electrical machine for mechanical to electrical energy conversion. Thus, an improvement of magnetic materials performance lead to an improvement of the electrical machine. To better understand all relevant materials parameters which have an impact on the magnetic properties, it is necessary to characterize materials in various experimental conditions. Then, starting from our observations, we can propose and improve models of magnetic behavior laws.
During this seminar, I’ll present you our work on the magnetic characterization of non-oriented sheets and bulk magnetic steel alloys, on the conductivity measurement and on the improvement of magnetic losses model.

 

February 15, 2018, Invited Seminar

Ruohan GONG (Wuhan University)

Ph.D. candidate of Electrical Engineering School of Wuhan University. Graduated from Physics and Technology School of Wuhan University with BE degree at 2012. Worked as an associated researcher in High voltage and Insulation Center of Wuhan University form 2012 to 2018. Major in Lightning-protection and Grounding, Electrical Engineering Materials, Multi-Physics Coupling Simulation of electrical devices and Inversion problem.

Study on Hot-spot Temperature Calculation and Inversion Detection Method of Oil-immersed Transformer

Power transformers are one of the most important equipment of the electrical power system. The operating reliability of transformers has a close influence on security and stability of power systems. The end of the life span of power transformers is most due to the loss of their normal insulation, which is very much dependent on the highest temperature occurred in any part of a winding insulation system, as known as hot spot temperature (HST). Thus, getting the values and location of HST is significant to meet the goals of maximizing the load ability, improving the effective lifetime and lowering the total cost associated with transformer operation and maintenance. Some works focused on this topic has been developed as follows:
(1) Considering the complicated and special solid-liquid-gas structure of oil-immersed transformer, the heat dissipation process inside transformer including heat conduction and convection is investigated by multi-physics coupling analysis. The validity and accuracy of calculation model is verified by temperature rise test.
(2) According to the temperature and velocity distribution analysis of inner transformer, an inverse detection method of HST based on support vector regression(SVR) is put forward. This method takes load and tank temperatures as input characteristics. The relative error of HST steady state temperature inversion is less than 3%.
(3) On the basis of steady inversion, an improved HST transient calculation method based on thermal-electrical analogy and IEC standard is proposed. The thermodynamic parameters of this model are estimated by Levenberg-Marquardt(LM) method. This model has been successfully applied to transformers with different voltage classes, capacities and structures. The maximum temperature difference is less than 3℃.



2017