Development of a simple nonlinear switched reluctance motor model using measured flux linkage data and curve fit

Abstract

This paper presents the formulation and simulation of a simple nonlinear switched reluctance motor (SRM) model. The model formulation is developed by first measuring the motor's flux linkage. A suitable 3 dimension shape function is developed to curve fit this data. Multiple shape functions are added together to reduce the mean square error of the flux linkage equation. We call this equation the Chan Series. Motor parameters such as inductance and back electromotive force coefficient equations are obtained by differentiating the Chan Series. The coenergy and motor torque equations are derived from the Chan Series by mathematical manipulation. Nonlinear model analysis is then carried out. Ways to indicate the motor size that takes into consideration the effect of magnetic flux saturation are proposed. Two motor relations are presented. Computer simulation of the model for chop, single-chop, and single-pulse modes are performed and compared to those published by S.K. Panda et al. (see IEE Proc., pt.B, vol.140, no.1, p.80-8, 1993). The comparisons show that the developed model can predict the SRM behaviour.