Speed – Torque Range Expansion of In-Wheel Axial-Flux SR Motor for Compact EV

Switched reluctance (SR) motors are robust and inexpensive since they consist only of iron cores and windings. Therefore, SR motors can be a potential candidate for in-wheel motors of electric vehicles (EVs). In previous papers, axial-flux SR motors (AFSRMs) for compact EVs were prototyped, and EV driving tests were successfully conducted. However, it was evident that the conventional control method, known as instantaneous phase torque distribution control (IPTDC), has a limited speed-torque range. This paper presents an improved control method, called variable commutation period control, to expand the speed-torque range, especially in high-speed regions. Additionally, an average torque control that can maintain large torque even in much higher speed regions is also proposed.