Low Torque Ripple Control of Switched Reluctance Motors Using Iterative Learning

Torque control of the switched reluctance motor is complicated by its highly nonlinear torque-current-position characteristics. The purpose of this paper is the development of simple and efficient control algorithms for the constant torque control of switched reluctance motors. The approach consists of two distinct steps, i.e., determination of appropriate phase current waveforms for some specified torque and the subsequent generation of suitable phase voltage profiles for faithful tracking of these waveforms by the respective stator windings of the motor. At both the stages of the control design, the principles -of iterative learning control have been exploited. Firstly, the desired current waveform is generated by repeated corrections from iteration to iteration starting from the conventional rectangular current profile as the initial waveform. This scheme requires much less a priori knowledge of the magnetic characteristics of the motor. In the second stage, the voltage profiles to be impressed upon the stator phases for the tracking of the desired current waveforms are leamed iteratively. Simulation results show impressive response characteristics for a four-phase switched reluctance motor.