Direct torque control of asynchronous motor based on improved controller

A new improved double-level hysteresis controller of flux and torque for the direct torque control of an induction was proposed,which has solved high torque ripple in low speed of conventional direct torque control,based on analyzing the rule of torque varying,the effect on torque changing of different voltage vectors.The proposed method was simple and eased to realize.Simulation and experimental results indicate that the improved controller extends the range of low speed operation and reduces the torque ripple,and increase the low speed torque while maintains the dynamic performance.