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

Permanent magnet synchronous machine with its simple structure, high efficiency, wide speed range, are widely applied in many fields, such as machine work, aerospace, electric traction etc., and direct torque control is a new type of high-performance AC driving system after vector control technique, as a result, the research of direct torque control of permanent magnet synchronous machine has become a focus. Therefore, this thesis take studies the high-performance direct torque control system of permanent magnet synchronous machine as a goal; it has important theoretical and practical significance.After consulted many literatures, the thesis introduced the structure and control strategy of permanent magnet synchronous machine, and then analyzed the status and trend of permanent magnet synchronous machine's direct torque control system.Based on space vector principle, the three kind of coordinate systems as well as the transformation of them which usually used in motor's speed control system are introduced, then, the mathematic models on different coordinate systems are derived, be based on that, the principle of traditional direct torque control system as well as the direct torque control system based on SVPWM are analyzed detailed, meanwhile, the realization process of SVPWM algorithm is derived, after that, the both simulation models are established in Matlab/Simulink, and then, the comparative analysis of simulation results are performed.The problems existed in the direct torque control system of permanent magnet synchronous machine are analyzed, and then, several improvements and modification have done in the traditional system as following: the traditional PI controller is been take the place by variable arguments PI controller, and a fuzzy controller with zero voltage vector as a part of its output has replaced the hysteresis Controller. The simulation results showed that the improved system has fast reaction, good dynamic and static performance, less flux and torque ripple.Finally, the hardware and software are designed based on TMS320F2812 witch is a digital signal processor chip of TI Ltd., which has certain significance in construct the direct torque control system of permanent magnet synchronous machine as well as for the further research.