Double fuzzy direct torque control system of BLDCM
ZHANG Jian wei1, SUN Wei qing1, JIN Jian zhong2
(1.School of OpticalElectrical and Computer Engineering，University of Shanghai for Science and Technology, 
Shanghai 200093,China;2.Shanghai Electric Tool Institute, Shanghai 201604, China)

Abstract: Aiming at issue that the direct torque control of brushless DC motor had large torque ripple and poor selfadaptability of traditional PID speed loop, the speed loop and torque controller of the direct torque control system were studied, and the direct torque control strategy was summarized, and a double fuzzy control strategy was proposed. In the speed loop, the basic PID controller was replaced by the fuzzy adaptive PID controller, and selftuning of the PID parameters was implemented. In the torque control loop, on the basis of the torque hysteresis controller,the torque deviation and the rate of change of the torque deviation were fuzzified,the action time of the nonzero vector and the zero vector was controlled by fuzzy control, and eliminates the hysteresis width selection torque ripple effect, so that further reduce the torque ripple. The results indicate that compares with the traditional direct torque control system of brushless DC motor, the direct torque control system with double fuzzy control strategy can further improve the selfadaptability of rotation speed and the antidisturbance ability of load torque,which greatly improves the control performance of the system.

Key words: brushless DC motor (BLDCM); direct torque control; fuzzy self adaptive PID; fuzzy control