Torque Ripple Minimization Strategy for Direct Torque Control of Induction Motors

In the traditional direct torque control (DTC) of induction motor, the low order harmonic component of stator current is very large when the motor is running at low speed. It leads to high torque ripple of motor in low speed. To solve this problem, a new control method has been proposed in this paper. Base on the traditional DTC method, electromagnetic torque and flux models have been analyzed. To further improve the torque response and reduce the torque ripple, fuzzy logic concept has been introduced into the flux model. The method of dynamic adjustment of the torque hysteresis amplitude is proposed. In this model, fuzzy variables are the speed and stator current error. Through the rationalization of fuzzy classification, the choice of voltage space vector is optimized. The results of simulation and experiment show that the method can not only improve the speed of torque response, and the problem of torque ripple can be effectively solved. In the whole speed range, the performance of dynamic and static is better than that of the conventional DTC.