Direct Torque Control And Experimental Research Of Asynchronous Motor

With the continuous development technology of ac (alternating current) speed regulation, the direct torque control strategy is becoming more and more important in the position of engineering practice. It has been widely recognized with its simple structure, fast torque response and good dynamic and static performance, and does not depend on a variety of motor parameters, etc.The history of the ac speed regulation is briefly introduced in this thesis, based on a large number of references. Mathematical model of the induction motor and the commonly used coordinate transformation are analyzed in detail. The basic principle of direct torque control are introduced. Through the analysis, because the traditional direct torque control system has many places needs to be improved, such as torque ripple, inverter switching frequency don’t constant,the accurate estimation of the stator flux linkage, etc. Space vector pulse width modulation (SVPWM) technology combined with new stator flux observer for the direct torque control technology is put forward in this thesis, call it the improved direct torque control strategy. The PI controller is used to instead of traditional hysteresis controller in direct torque control system, and the new flux observer is used to instead of the traditional pure integral observer, then the simulation model is established, proves that the new flux observer observation accuracy has improved significantly. Simulation research in the MATLAB/Simulink tool, and a detailed analysis to the result of the traditional DTC system, proves the correctness and feasibility of the direct torque control strategy. Through the analysis of the improved system simulation results, proves that the improved system can eliminate the torque ripple, accurate estimation of stator flux and solve the problems of the inverter switching frequency not constant.The thesis based on dsPIC33FJ128MC706A Digital Signal controller launched by microchip technology companies in the United States, as the core control chip to build the hardware platform and debug software in MAPLAB development environment. Finally, get good results.