Design optimization of a 12/8 Switched Reluctance Motor for electric and hybrid vehicles

Abstract

The Switched Reluctance Motor (SRM) is a magnetless type of electric motor that has recently received an increasing interest for electric and hybrid vehicle applications. One major advantage of SRMs is that they have the lowest material costs. On the other hand, they suffer from relatively high torque ripples, which can make the motor noisy and less efficient. In this paper, the design and optimization of a 12/8 toothed SRM is presented. The goal of the optimization was to analyze and modify the motor geometry in order to optimize the average torque while trying to minimize the torque ripples at the same time. The first step of the optimization consisted in finding the optimum number of winding turns: 7, which was lower than that of the initial design and allowed the rotor diameter to be increased by 24.9%. This resulted in an increase in average torque of 38.3 % and a decrease in torque ripples of 17.3 %. The next steps consisted in changing the shape of the winding slots by varying other geometrical dimensions and the rotor tooth width. It resulted in a non-negligible additional reduction in torque ripples of 10.2 % and in an average torque further improved by only 2.4 %. This shows that increasing the rotor diameter is the most effective way to increase the torque from the initial design considered, while the other parameters were already quite well dimensioned in this initial design.