An improved DTC algorithm for reducing torque ripples of PMSM based on fuzzy logic and SVM

There are big ripples on current and electromagnet torque under traditional hysteresis direct torque control (HDTC) on motor drive system. To solve these problems, a fuzzy logic controller is designed to instead traditional hysteretic comparator in this paper, and zero voltage vectors are used to further reduce ripples. The torque error, the flux error and stator flux position are used to select two adjacent active vectors and its ratio of active time. Zero voltage vectors effective time is determine by the output of fuzzy logic controller based on the torque error magnitude and flux error magnitude. Arranging the inverter switching in this manner, results in fast torque response and minimum torque ripples as compared to the traditional HDTC. The simulation results have verified the effectiveness of this method.