Laurent Bernard

Thermal Model With Winding Homogenization and FIT Discretization for Stator Slot

The aim of the method detailed in this paper is to get an equivalent thermal model of a stator slot, in order to simplify the calculation of desired temperatures in an electrical machine winding. This study is divided in two steps: First, the equivalent thermal conductivity is deduced from a homogenization of the winding, and next, a discretization is achieved using the finite integration technique considering transient analysis. In order to evaluate the method, results from the equivalent model are compared with finite element simulations considering two slot geometries.

Effect of Stress on Switched Reluctance Motors: A Magneto-Elastic Finite-Element Approach Based on Multiscale Constitutive Laws

The design of electromagnetic devices submitted to high mechanical stress is a growing issue and requires consequently appropriate modeling tools. We propose in this paper to implement a multiscale model for magneto-elastic behavior into a finite-element code. The 2-D magneto-elastic constitutive law is derived from a multiscale model based on a local energetic approach. The method is applied to study the effect of stress on the magnetic behavior of a switched reluctance motor. This work provides a finite-element tool for the modeling of the effect of multiaxial stress on electrotechnical devices.

Evaluation of Electromagnetic Fields in Human Body Exposed to Wireless Inductive Charging System

This paper presents an evaluation of the EMFs in the human body exposed to the wireless inductive charging system of electric vehicles such that the compliance of this charging system with respect to human EM exposure limits can be examined. A magnetic resonance imaging-derived and high-resolution model of the human body is used. An exposure assessment of a representative wireless inductive charging system, under a limited set of operating conditions, is provided to estimate the induced EMFs. The numerical analysis is performed with the finite element method. Numerical modeling of the system next to a standing human model shows that the EM exposure limits can be absolutely satisfied even when the transmitter coil is very close to the body. Furthermore, the worst configuration for the exposure evaluation of the wireless charging system is taken into consideration. This paper provides a useful guideline for the industry to develop inductive charging systems following the safety standards of radiation protection.

Advanced Modeling of a 2-kW Series–Series Resonating Inductive Charger for Real Electric Vehicle

This paper focuses on the design of a contactless charging system for electric vehicles (EVs) using inductive loops connected to a resonance converter. The study carries out the system operation, electromagnetic radiation, and testing. It is shown that the presence of the chassis leads to a double resonance and has a strong influence on the radiated fields.

Efficient Implementation of the UPML in the Generalized Finite-Difference Time-Domain Method

In this paper, we show how to use hexahedral and prismatic elements for the efficient development of uniaxial anisotropic dispersive media (UPML) around an initial unstructured tetrahedral primal mesh using the generalized finite-difference (GFD) method. The initial mesh is assumed to have plane external boundaries. Taking into account the properties of the UPML medium, we build a special discrete Hodge in order to have a simple scheme for the time-domain solution of Maxwells equations. The method is presented for the general 3-D case and numerical results show its efficiency.

Homogenized Magnetoelastic Behavior Model for the Computation of Strain Due to Magnetostriction in Transformers

This paper deals with the prediction of the deformation of a multilayer transformer core made of an assembly of anisotropic E-shaped and I-shaped sheets. This magnetomechanical coupled problem is solved by a stepping finite-element method sequential approach: magnetic resolution is followed by mechanical resolution. A 3-D simplified multiscale model describing both magnetic and magnetostrictive anisotropies is used as the constitutive law of the material. The transformer core structure is modeled in 2-D, and a homogenization technique is implemented to take the anisotropic behavior of each layer into consideration and define an average behavior at each element of the finite-element mesh. A three-layer transformer prototype is fabricated with Hi-B grain-oriented iron-silicon alloy. Experimental measurements are carried out and compared with the modeling results. Small discrepancies are observed and discussed.

Electromagnetic model of EV wireless charging systems in view of energy transfer and radiated field control

A wireless charging system for electric vehicle (EV) is considered. A 3D Finite Element (FE) model of the inductive coupler is developed in order to compute the inductances and the radiated magnetic field around the system. In addition, a circuit model associated tofield computation allows determining the electric behavior of the system during charging. Simulation results are then validated by comparison withexperimental measurements. The developed model allows the design of the system considering the optimization of the energy transfer and the radiated electromagnetic compatibility (EMC) compliance.

3-D Modeling of Thin Sheets in the Discontinuous Galerkin Method for Transient Scattering Analysis

This paper presents a modeling of thin sheets. An interface condition based on analytical solution is used to avoid a fine mesh. This condition is integrated in a time-domain discontinuous Galerkin method to evaluate the shielding effectiveness. This approach is validated by a comparison with analytical solution. 2-D and 3-D cavities are simulated to illustrate the efficiency of the condition.

Three-Dimensional Generalized Finite-Difference Modeling of Electromagnetic Time Reversal: Impact of the Density of Dipoles for the Localization of a Dielectric Obstacle in Free Space

This paper presents a three-dimensional (3D) full time-domain modeling of the time reversal process for the localization of a dielectric obstacle in free space using an array of transceivers made of electric dipoles. The main purpose of this study is to propose a localization method and analyze the influence of the density of dipoles in the Time Reversal Array (TRA) on the accuracy of the localization in a given electromagnetic configuration. A Generalized Finite Difference (GFD) method and a leapfrog time discretization are used to get the numerical results.

Electromagnetic fields in body by wireless inductive system

Purpose – The purpose of this paper is to calculate the induced electromagnetic fields in human body exposed to the wireless inductive charging system of electric vehicles has been conducted based on the numerical simulation. Design/methodology/approach – A homogeneous human body model is built and a representative wireless inductive charging system is used for the exposure assessment. The numerical simulation relies on finite element method with formulations in terms of the magnetic vector potential. The electromagnetic fields in terms of magnetic flux density and electric field are computed in the human body and compared with the electromagnetic exposure limits. Findings – It has been found that the induced EMFs in the near-field exposure configuration greatly comply with the safety guidelines. Originality/value – This study could help the development of the wireless inductive charging system with meeting the safety standard of radiation protection.