Research Of The Direct Torque Control For Permanent Magnet Synchronous Motor Based On DSP

The direct torque control (DTC) strategy for asynchronous AC motor was proposed by M.Depenbrock In 1985. The DTC scheme has resolved the complex problems that completely decoupled control of rotator magnet field orient in vector control scheme for ac motor .based DTC scheme the torque and stator flux linkage of the AC motor is controlled directly by selecting the voltage space vector properly, which shows the better performances in high dynamic and steady state operation. DTC scheme has been widely used in the induction motor drive system. Recently, the researches of DTC techniques for permanent magnet synchronous motor (PMSM) have become focus point. Compare with the vector control, DTC has some drawbacks that the ripples in flux and torque are relatively higher at low speed. This paper has investigated the basic principle of DTC and studied the fuzzy zero vector distribute scheme for PMSM. Two novel DTC strategies that based on reference voltage vector scheme and reference flux linkage space voltage vector modulation scheme for PMSM are proposed. The simulation results show that the flux and torque ripples are greatly reduced and all the advantages of basic DTC are still retrained. In addition, switching frequency of inverter is probably fixed. An Experimental system that using TI Company TMS320F240DSP as controller is designed.