Consideration of Number of Series Turns in Switched-Reluctance Traction Motor Competitive to HEV IPMSM

This paper shows a winding design consideration of a 50-kW switched-reluctance motor (SRM) for hybrid-electric-vehicle (HEV) applications. Increasing the number of turns in stator windings is effective in reducing the maximum current; thus, the inverter current rating is reduced. However, motor output power falls significantly at high speed because of the increased back electromotive force. Continuous current operation can enhance output power at high rotational speed. In this operation, phase current is increased, and hence, the motor output power is maintained at high rotational speed. However, continuous current operation results in a decrease in efficiency. Thus, there is a tradeoff in selecting the number of series turns. In this paper, two SRMs are constructed with the same dimensions, and their performance results, i.e., torque and efficiency ranges, are compared with those of the automotive industry standard interior-permanent-magnet motor for HEV applications.