Direct Torque Control Strategy of Induction Motors Based on Predictive Control and Synthetic Vector Duty Ratio Control

The reasons of torque ripples and flux trajectory resulted by conventional direct torque control of induction motor are discussed. A new control strategy combined predictive control algorithm with synthetic vector duty ratio control technology is proposed based on the discussion to improve the performance of Direct Torque Control (DTC). This method based on the current stator flux linkage and torque deviation calculates a stator voltage to compensate for the current vector which is used in the next control period, then the stator flux linkage and torque deviation just be eliminated. Then applying synthetic vector duty ratio control technology to determine the action time of the active voltage vector which is synthesize by selected voltage vector and zero vector in the sample period. Simulation results show that the proposed DTC strategy can effectively reduce torque ripple, improve the magnetic flux trajectory.