Christian Chillet

Magnetic moment and reluctance network mixed method applied to transformer modeling

The aim of the study is to find a method to model electromagnetic devices which generate consequent magnetic leakage. Classical methods have proved to be efficient but time consuming. The method proposed in this paper is based on the magnetic moment method (MMM). An original methodology to obtain a simplified MMM model is described, adjusted with simple RNM model results. Besides the good accuracy, the simplicity of the model makes it possible to consider complicated studies with reasonable resolution times.

Simplified magnetic moment method applied to current transformer modeling

The aim of the study is to find a method to model electromagnetic devices which generate consequent magnetic leakage. Classical methods have proved to be efficient but time consuming. The method proposed in this paper is based on the magnetic moment method (MMM). We first introduce MMM and present a comparison with the finite-element method in transient conditions. Then, a methodology to obtain a simplified MMM model is described. Beside the respectable accuracy, the simplicity of the model makes it possible to consider more complicated studies with reasonable computation times.

Efficient Reluctance Network Formulation for Modeling Design and Optimization of Linear Hybrid Motor

The aim of this paper is to propose an efficient and unique reluctance network (RN) model for all translator displacements of a linear hybrid motor. This model has to consider several translator positions to analyze the linear motor performances. The proposed RN model takes into account the magnetic characteristic and the flux leakage. Consequently, the proposed model gives precise results of the electromagnetic characteristic. The RN model considers an interesting solution to deal quickly with an optimization task of a large number of constraints and parameters. The developed model is coupled with sequential quadrating programming method for an optimization process of the linear machine. The obtained results confirm the efficiency of this method for modeling and optimization of the linear machine.

Cost ? performance ? size optimization for automotive induction machines: A fast and accurate FEM, analytical model and optimization mixed procedure

Purpose – Seeks to posit a new procedure to optimize the geometry of an electric motor for hybrid vehicles (HV), based on an optimization model implementing the complex specifications, environment‐sizing constraints and vehicle‐operating points.Design/methodology/approach – In this work, induction machines (IM) were studied for automotive traction applications, more specifically, for HV. The necessary models and methods to analyse and design such electric machines were developed. A limited number of finite element computations was used to establish a non‐linear electromagnetic model of the machine. This model was then adapted to study the sensitivity of the design for the most significant geometric variations. Thus, one can easily adapt a machine for new sizing requirements.Findings – This modelling methodology was extended to take into account a great number of parametric variations. This model was used for constrained optimisation on the geometry of a machine. To achieve this, a new “reset model optimis...

Loss Minimization of an Electrical Vehicle Machine Considering Its Control and Iron Losses

In this paper, optimization of the control of an electrical machine allowing a minimization of its total losses is described. It is based on the use of an iron loss model [loss surface (LS) model] coupled to the electromagnetic finite-element simulations of the machine. The LS model is a scalar and dynamic hysteresis model developed many years ago at G2Elab and tested for iron loss prediction in several cases of electric machines. It is first characterized and improved in this paper for M330-35A SiFe sheets. Then, it is associated with a finite-element analysis to compute, in a post-processor mode, the local and global magnetic losses in the machine. For electric vehicle application, the whole torque-speed variation should be investigated. To do that, a quick response surface is constructed from a small number of simulations and the iron loss is determined. Then, a suitable optimization algorithm is developed. This approach is then illustrated by a case study and compared with classical optimization in which only the copper losses in conductors are considered. Gains of up to 50% reduction in the total losses of the machine in certain operating areas are observed.

An Analytical Approach of Magnetic Diffusion in a Plate Under Time-Varying Flux Excitation

A new analytical computation of magnetic flux distribution and eddy currents is proposed in this paper. Equations are set down for a plate subjected to a time-varying flux excitation. This method consists of using Neumanns boundary conditions in the flux-density diffusion equation to consider the instantaneous variations of the imposed flux waveform. The diffusion equation is solved by separation of variables and Duhamels theorem. Different cases of imposed magnetic flux are studied: sinusoidal flux, flux ramp, and arbitrary time-varying flux. This new analytical method is a complement of the classical approach (with Dirichlets boundary conditions) where induction at boundary needs to be corrected to fit the instantaneous total flux. In this paper, a distinctive method allows to compute the instantaneous distributions and corresponding losses directly from the experimental flux measurements on electromagnetic devices. The analytical expressions of magnetic flux density and eddy current distributions are explicitly given. The comparison between analytical and finite-element simulation results shows the validity of the new analytical method.

Analytical computation of the instantaneous transient magnetic flux and eddy current losses in the armature of a magnetic actuator

An analytical method for computing the instantaneous transient magnetic flux and the eddy currents losses in the armature of an actuator driven by current is proposed. The analytical method consists in modeling the armature by a circuit with reluctances and “eddy inductances”. The difference between this work and the previous ones is the fact that the analytical expressions of reluctances and “eddy inductances” are identified from the Joule effect losses and the magnetic energy in the studied armature, when a known sinusoidal magnetic flux goes through it. The presented analytical model takes into account the skin effect and brings a better accuracy on a larger range of frequency. A ladder circuit of fixed value reluctances and “eddy inductances” is also introduced, in order to approximate the response of the “exact” circuit. In that case, it is more practical for time response study and circuit simulations.

Wound magnetic core consequences on false residual currents

Purpose – Geometric or magnetic anomalies in the wound magnetic core of a residual current circuit breaker can be responsible of its abnormal tripping. The purpose of this paper is to analyse the core shape contribution to false residual currents (FRCs).Design/methodology/approach – To study precisely the core shape contribution, FEM simulations are investigated. First a 2D multilayer geometry is described thanks to linear regions. Then an apparent anisotropic bulk core is developed and validated in 2D and in 3D.Findings – The air gaps between the magnetic layers develop a shielding effect responsible of the core high sensibility to primary conductors eccentricity. This effect can be easily represented using an anisotropic bulk core model.Research limitations/implications – The anisotropic material model is basic and has known limitations. Future research should see the development of a new model.Originality/value – FRCs can considerably disturb operation of residual current device. This paper provides ne...

Reluctance network model for linear switched reluctance motor

This paper presents a new reluctance network model developed in aim to design and optimize the linear switched reluctance motor. The developed reluctance network model is verified using finite element method. This reluctance network model takes an account the saturation of the ferromagnetic parts of the actuator. Also, the dispersion flux is modeled with a particular reluctance. Consequently, the reluctance network model gives precise results of the flux and the force. On the other hand, the important interests of the proposed reluctance network model is that this model can be coupled with other tools in aim to optimize the linear machine.

Citation in machine

This paper describes a method to study the electrical steels with regard to their application. This methodology attempts to link the design of the electrical machine with the practical magnetic material behavior thanks to visualization tools. Firstly, some magnetic characterization are presented to determine the electrical steel behavior and to validate the hypotheses and the model considered. Then, the methodology and visualization tools are exposed. As a result, useful information is extracted to help the experimenter to dimension the characterization bench and to define the maximum frequency to be measured in order to have the best representation of the material behavior within the application.