Asynchronous Motor Direct Torque Control System Torque Ripple Suppression Countermeasures

In the field of AC Speed Regulation, the large torque ripple in Direct Torque Control (DTC) system is researched in recent years. The basical principle of DTC system and the control course of the induction motors' DTC system is described in detail. The influence of the control cycle and the inverter switch element is analysed, and the mechanism of the large torque ripple is researched. In order to reduce the larger torque ripple, two kinds of control strategy based on duty ratio control technique of induction motor drives are presented by making use of predictive strategy. Two of them can reduce the torque ripple by predicting the control time. Then, the methods have been carried on comparative analysis, and the second method is improved by combining with DSVM, which improved the predicted accuracy further. Based on the MATLAB6.5/Simulink platform, a good DTC simulation system is constructed, and the simulated results can prove that the large torque ripple have been over come remarkably.Because of existing the error during the process of calculating time, the duty ratio control technique still produce a larger torque ripple. A single neuron adaptive PID controller is used to substitues the speed PI controller, and the supervisory Delta study rule is combined with non-supervisory Hebb study rule, which enhances the self-study ability of single neuron PID controller and realizes parameter optimization and self-turning. The system not only has good static and dynamic performance, but also can reduce the torque ripple further.