Current Threshold Scheme for Torque Ripple Reduction of a 4/2 Switched Reluctance Motor

Abstract

Switched reluctance motors are becoming increasingly attractive in various fields and for various applications including for electric vehicles. It is controlled by activating and deactivating the phases of the motor during the positive inductance slope of each phase. A simple way to do this is to excite each phase according to the edges of sensor outputs aligned to the phases. However this method is very crude and results in a fixed dwell angle. This fixed dwell angle results in unusual torque waveforms which may lead to a reduction in overall torque. This paper discusses the control of a 2-phase 4/2 SRM used for electric superchargers and introduces a simple novel control method based on sensor excitation and current threshold control. This includes a self-starting procedure and also a compensation mechanism adapted from the simple sensor-based excitation. Simulations and experiments were done to verify the proposed methods.