A complex fuzzy controller for reducing torque ripple of brushless DC motor

Abstract

The Brushless DC Motor (BLDC) has been applied widely for its high torque density, high efficiency and small size, but its torque ripple is relatively high. In recent years, some scholars apply direct torque control to BLDC, for reducing torque ripple by means of the fast response of torque. Based on this theory, this paper presents a complex fuzzy controller which comprises two fuzzy controllers. The first controller is designed to select correct voltage vector according to the torque error, stator flux-linkage error and electric angle of stator flux-linkage. The second fuzzy controller with adjustable factor is designed to regulate the action time of voltage vector according to the torque error and torque error differential. For minimizing the torque ripple, the genetic algorithm (GA) is utilized to optimize adjustable factor. The whole system is simple, the control method is convenient to be realized and the effect is significant. Simulation and experiment results verify the effectiveness of the complex fuzzy controller. © 2009 Springer Berlin Heidelberg.