Research On The Direct Torque Control System Of Permanent Magnet Synchronous Motor

Direct Torque Control (DTC) method of asynchronous motor is proposed by M.Depenbrock In 1985, the DTC is simple and effective and is successfully used in servo system of asynchronous motor, But most researches of DTC are focused on asynchronous motors and until recent years some researches began to research the application of DTC into Permanent Magnet Synchronous Motor( PMSM). For the research is still in its primary stage, many questions need to be solved. In this paper, the application of DTC into PMSM is discussed first, and then simulation of PMSM DTC is implemented based MATLAB. Secondly, for the problem of torque ripple at low speed, a new PMSM DTC system based on fuzzy logic is proposed and simulation results show that the torque ripple is decreased dramatically. In basic DTC, flux estimation error is existed due to the measure errors and uncertainties of machine parameters. To overcome the drawbacks, the observer for PMSM stator flux linkage estimation is presented. The simulation results show that observed flux is more precise and stronger robust than conventional flux model. Simultaneous the accurate rotator position and speed estimation are obtained. Finally, a comparison of the performance of each observer is presented.