Improved direct torque control for asynchronous motor based on SVPWM

To decrease the problems of flux ripple and torque ripple in the conventional direct torque control(DTC),a novel direct torque control system based on SVPWM(space vector pulse width modulation) for asynchronous motor was scheme presented.The new system was established on the analysis of the stator field oriented mathematical model of asynchronous motor in α-β coordinates system,as well as the space voltage pulse width modulation(SVPWM) technology,and improved the traditional induction motor direct torque control system.In this system,based on the difference between the actual torque with theoretical torque and the actual stator flux with theoretical flux,the SVPWM control signal was determined by the optimal vector control table to control the asynchronous motors.Due to the torque and flux can be compensated at the sampling,the torque ripple and flux ripple in the asynchronous motor was reduced in the system.Finally the control system model was simulated by Matlab/Simulink.Simulations and experiment results show that the system can effectively decrease the torque ripple and flux ripple.