A Fuzzy Logic Based Current Modulator for Torque Ripple Minimization in Switched Reluctance Motors

Abstract

This paper addresses a fundamental control issue in switched reluctance motor (SRM) drives - the torque ripples. Conventionally, the amplitude of the rectangular reference current pulse, on-angle, and off-angle for the various phases of the SRM for a given torque demand are obtained from a stored look-up table that makes use of measured torque-current-position characteristics. However, the electromagnetic torque, thus obtained, contains significant ripples. A number of techniques for the generation of reference current profiles that minimize the torque ripples have also been suggested in the past. But due to highly nonlinear characteristics of the SRM, all these schemes are not fully successful. Moreover, their performance depends greatly on the accuracy of the magnetic characteristics measurements of the motor on which most of these algorithms work. Our work is primarily motivated to modulate the reference phase current pattern with the aid of fuzzy logic which is well suited to compensate for the nonlinearities of the system, so that the torque ripples are further suppressed. Performance of the proposed strategy is verified by computer simulation.