Modeling And Simulating The Direct Torque Control System Of Asynchronous Motor Of Electric Vehicle

The paper summaries the series issues of energy, climate, noise, illness, pollution, due to the rapidly increasing number of the automobiles on the earth. The future vehicle will be clearer and consume less fuel. As the key important part of vehicle, motor system's characteristic was researched by many researchers and scholars. In the preface all kinds of drives system used on electric vehicle are introduced and the process of regulation the speed of motor by Alternating current was narrated.In second chapter Pulse-Width Modulation's theory is discussed. In the same time the author tell of the voltage space vector Pulse-Width Modulation's theory. Arithmetic of flux linkage 's track is discoursed on, whose shape is hexagon or circle. How to model a dynamic mathematics model of asynchronous motor and how to exchange the parameter in different coordinate system such as M-T or d-q system, are recommended in chapter 3.The most important things are the theory of directly torque control system and modeling and simulation the control system. When the idea of the directly torque control system appears and the strongpoint of the system are pointed out by author. With the help of simulation system of MATLAB, every part of the directly control system is building up, such as motor's model, the flux linkage 's observer model of stator, the torque observer model, the select model of voltage space vector, the model of stator's flux linkage 's space interval judge, the model of the inverter, the model speed's PI regulation. During simulation, the load of motor is constant and the value of stator's flux linkage tolerance is different, we can observer the speed 's change, the change of stator 's flux linkage and the change of motor's torque. Using the same method, we use different torque tolerance, different value of P and I to observer the change of speed. And so on we also observer the change of torque and stator flux linkage. We get the results that the smaller the torque tolerance the less fluctuate of motor torque, the less value of stator flux linkage the shape of stator flux linkage will be closer to ideal flux linkage. The values of P,I are relate to the shape of speed's figure and torque 's figure, they affect the response time and overshoot of speed and torque. At last a step load is added to the motor system, it has a good dynamic characteristic. This directly torque control system is approved, which can help the engineer to do some reference.In the conclusion some work must do deeply and widely in the coming days are list to make the control system sophisticate.