Direct torque control system for asynchronous motor based on DSVM

Direct torque control uses the pure integral voltage model for torque observation. The problems of accumulate error and direct current excursions will cause the fluctuations of current and torque. A modified model of flux observation is put forward. It is composed of two models. The open loop current model uses flux observation in low speed range. The self-adaptation voltage model uses flux observation in all speed range. A feedback is imported for voltage model to observe stator flux and correct error by using PI adjuster. The observation precision is greatly improved. The dynamic performance of direct torque control system for asynchronous motor is also improved by using discrete space vector modulation (DSVM). Simulation and experimental results prove the validity of this method.