Yvan Lefevre

Finite elements coupled to electrical circuit equations in the simulation of switched reluctance drives: attention to mechanical behaviour

A method to model the switched reluctance motor is presented in this paper. The methodology is based on the simultaneous solution of the magnetic field, represented by the two-dimensional finite element method, with electrical circuit equations. With this model, the currents in the windings are calculated and the force distribution on the stator teeth is obtained. The mechanical response to magnetic forces is calculated by a finite element code.

Electro-magneto-mechanical characterizations of the vibration of magnetic origin of electrical machines

This paper contributes to the modelling of vibration of magnetic origin of electrical machines. It is generally difficult to calculate the damping matrix of actual mechanical structure of electrical machines. The mechanical model that we present here is known as the modal superposition method. It allows us to take into account the damping coefficients of the mechanical structure which can be inferred from experience. Associated with a numerical code for the computation of magnetic force it can be of a great help in the predetermination of the vibration of an electrical machine. >

Some Co-Axial Magnetic Couplings Designed Using an Analytical Model and an Exact Global Optimization Code

The purpose of this paper is to use a new rational approach for the design of some magnetic couplings. Our method is based on the association of analytical models and an exact global optimization algorithm named IBBA and developed by the third author. The analytical model presented in this paper is more sophisticated than those previously dealt using IBBA. Therefore, some under and over estimating functions have been constructed for those particular problems of design in order to improve the convergence of IBBA. Some optimal results highlight the efficiency of this approach.

Optimization of the Settings of Multiphase Induction Heating System

This paper deals with the setting-parameter optimization procedure for a multiphase induction heating system considering transverse flux heating. This system is able to achieve uniform static heating of different thin/size metal pieces without movable inductor parts, yokes, or magnetic screens. The goal is reached by the predetermination of the induced power-density distribution using an optimization procedure that leads to the required inductor supplying currents. The purpose of the paper is to describe the optimization program with the different solution obtained and to show that some compromise must be done between the accuracy of the temperature profile and the energy consumption, with the calculation of the losses.

Design of Electrical Rotating Machines by Associating Deterministic Global Optimization Algorithm With Combinatorial Analytical and Numerical Models

This paper presents a new methodology of design of electrical rotating machines. The methodology is an extension of previous works of the second author. Indeed, associating combinatorial analytical models with exact global optimization algorithms leads to rational solutions of predesign. These solutions need to be validated by a numerical tool (using a finite-element method) before the expansive phase of hand-making a prototype. Such an automatic numerical tool for computing some characteristic values, such as the torque, was previously developed. The idea of this paper is to extend the exact global optimization algorithm by inserting the direct use of this automatic numerical tool. This new methodology makes it possible to solve design problems more rationally. Some numerical examples validate the usefulness of this new approach.

A 2D finite element formulation for the study of the high frequency behaviour of wound components

When the frequency of power converters increases, their wound components, such as inductors or transformers, can no longer be supposed ideal. In this paper, a formulation using 2D finite elements is presented for studying these high frequency coupled magnetic and electric field problems (eddy currents, proximity effects and stray capacitance). This formulation is based on a particular division of the 3D spatial domain which enables a 2D calculation.

First Approach for the Modelling of the Electric Field Surrounding a Piezoelectric Transformer in View of Plasma Generation

This paper is about an open multi-physics modelling problem resulting from recent investigations into plasma generation by piezoelectric transformers. In this first approach, the electric field distribution surrounding the transformer is studied according to a weak coupling formulation. Electric potential distribution views obtained numerically are compared to real views of plasma generation observed experimentally.

First steps towards design, simulation, modelling and fabrication of electrostatic micromotors

Following the principles proposed by workers at Berkeley University, we have developed a version of the electrostatic micromotor based on the sacrificial layer method combined with oxidation of the rotor. In order to study the behaviour of this electrostatic micromotor, we have elaborated two softwares. The first, called EFCREL, is to simulate the static operation of the electrostatic micromotors and the second, called EFDYN, is to simulate their dynamic operation. Both are based on a finite-element code, called EFCAD, for electromagnetic field computation. They help us with the design of the fabricated micromotor and the simulation of its dynamic working, respectively. The elaboration of these two softwares represents our first steps towards a fully integrated CAD (computer aided design) system for micromotors.

Analytical modeling of electrical potential repartition on piezoelectric transformer

This article deals with an analytical modeling of the electrical potential repartition generated on the surface of receiving part of a piezoelectric transformer. The analytical model is exploited to verify the influence of structural and geometrical parameters on the amplitude and the repartition of electrical potential. Additionally, a 2D-model of surrounding electrical potential is undertaken by Finite Difference Method (FDM) from a weak coupling approximation.

Theoretical and experimental studies of the effects of the feeding currents on the vibrations of magnetic origin of permanent magnet machines

A computation procedure of vibrations of magnetic origin is used to study the effects of the feeding currents on the vibratory behavior of a permanent magnet synchronous machine. Similar studies are effected on an experimental bench dedicated to test electrical machines and their electronic supply devices. Characteristics of the vibrations produced by feeding currents are deduced from the comparison of the simulations results and measurements. >