Y. Lefevre

Finite element torque calculation in electrical machines while considering the movement

Different methods are presented for the calculation of torque as a function of rotation angle in an electrical machine. These methods are integrated in a calculation code by using the finite element method. The movement is taken into account by means of the moving band technique, involving quadrilateral finite elements in the airgap. The torque is calculated during the displacement of the moving part by using the following methods: Maxwell stress tensor, coenergy derivation, Coulombs virtual work, A. Arkkios method (1988), and the magnetizing current method. The results obtained by the different methods are compared with experimental data and make it possible to obtain practical information concerning the advantages and limitations of each method. >

Compensation of permanent magnet motors torque ripple by means of current supply waveshapes control determined by finite element method

A method for determining the supply current waveshapes for torque ripple compensation in permanent-magnet motors without saliency and damping bars, by means of a finite-element code, is presented. First, a theoretical analysis shows that current waveshapes producing constant torque can be determined. This analysis leads to an expression for the current as a function of the motor EMF (electromotive force) and cogging torque. Several methods, based on finite-element computation of the magnetic field, for computing the cogging torque and EMF are proposed and compared. A special experimental bench for motor torque measurement is used to validate the theoretical results. >

Finite element simulation of electrical motors fed by current inverters

This paper presents a methodology for coupling electrical machines represented by a Finite Element Model and power electronic devices. The technique, based on a time-stepping procedure for the simultaneous solution of the field and the electrical circuit equations, is applied to an inverter current fed permanent magnet motor.

Determination of synchronous motor vibrations due to electromagnetic force harmonics

A method for the computation of magnetically induced stator vibrations in synchronous motors is presented. The electromagnetic field in the motor is calculated, and the fluctuations of the magnetic forces applied to the teeth of the stator are evaluated. The harmonics of these magnetic forces are calculated by means of a mechanical finite-element analysis, leading to determination of the motor vibrations. The method is used to compare vibrations produced by two permanent-magnet synchronous motors of different magnetic structures, one with radially oriented magnets and one with tangentially oriented magnets. The results clarify the mechanism of generation of the vibrations. >

An original and natural method of coupling electromagnetic field equations with circuit equations put in a state form

In this paper a general method of coupling static converters with electromagnetic devices is presented. This method is based on the simultaneous solution of the converter equations and the field equations in the electromagnetic devices. The equations are established in an automatic way: the circuit equations are put in a state form and the field equations are discretized using a 2D finite element method. An original way of linking the two systems of equations is proposed.

Synthesis and modelling of an electrostatic induction motor

This paper deals with a new way of synthesis and modelling of electrostatic induction micromotors by means of duality rules from the magnetic induction machine. An electromechanical model based on this method is given. Then, a computational procedure based on a general lumped parameter model and an electric field calculation code, has been developed so as to simulate the dynamic working of these actuators. A comparison is made between the computation results and the model results. Satisfactory agreement between theory and simulation is obtained in most respects. >

Building a CAD system for educational purpose based only on a mesh tool and a finite elements solver

The article discusses about the use of finite elements method (FEM) software in order to help lecturer to teach design of electrical machines. Nowadays, lecturers have less and less time to teach the design of electrical machines. Special tools based on FEM can help them in this task. For the past years, such tools needing sophisticated environments have been realized for designers in industry. Assuming minimum equipment, requirements and guidelines for the realization of a specific tool are presented

Integration of control loops in coupled field circuit model to study magnetic devices supplied by power electronic converter and their control

In this paper, we present a method to take into account the feedback control in software developed from coupled field circuit models. The implementation of control loops is done in a software which is able to simulate electromagnetic devices associated with power electronic circuits having a time dependent topology. The control strategy is implemented in a discrete‐time version and can manage all controllable electronic switches by means of different electric or magnetic quantities calculated during the simulation (flux, currents, voltages,u2009…). Electrical systems involving magnetic devices, power electronic converters and their control devices can be simulated in presence of phenomena such as eddy currents or saturation of the magnetic materials.