Analytical modeling of switched reluctance machines including saturation

Nowadays, the switched reluctance machine has become a serious candidate in industry applications : hybrid electric vehicles, aircraft starter/generator systems and washing machines. Because of the rapid progress in processors (DSP), control algorithms are becoming more and more promising. Nevertheless an accurate model is essential, first to predict its performance and obtain high quality control, and second to use sensorless controllers enabling cost reduction and reliability increase. This paper presents an analytical model of the inductance and of the torque, based on the results of a 2D finite element analysis (FEA) applied to an 8/6 prototype machine. The model takes into account the nonlinear characteristics due to the magnetic saturation. The position dependency is represented by a limited number of Fourier series terms and the nonlinear variation with current is expressed by means of polynomial functions. The analytical calculations are introduced, then the results of the proposed model are compared to those issue from the 2D FEA approach.