Direct Torque Control Of Permanment Magnet Synchronous Motor Used In Electric Vehicles

With the popularity of the car, the problems caused by traditional car should not be ignored. For instance strongly dependent on unrenewable energy, increasing carbon dioxide emissions and aggravating environment pollution. These problems caused a serious threat to national security and the life of people. The world's major automobile manufacturers regard the electric car as important development direction of solving these problems. At present, our country also gives a high degree of attention to the development of electric vehicle technology. And to master the electric car motor drive technology, will be to master the electric car core technology of the key. Electric motor vehicle driver technology is one of the most critical electric vehicle technologys.In recent years, with the permanent magnet material technologies continue to mature and the costs continue to decrease. Permanent magnet synchronous motor with its high energy density, high efficiency and easy maintenance win more and more extensive attention. This paper take the permanent magnet synchronous motor used in electric car as a controlled object, and researched on direct torque control methods.Based on the description of the coordinate system motor common used and the relationship between some coordinate transformation, and then analysised and established the permanent magnet synchronous motor mathematical model. At the end, the system state space equation is given with torque and flux amplitude as output. As the Bang-Bang DTC exists problems as need high frequency control, difficult to achieve, a sliding mode control DTC method is proposed. Based on the system state space equation, a sliding mode control law was designed and stability is proved by selecting a Lyapunov function. Then the MATLAB/SIULINK simulation implementation of direct torque control based on the sliding mode is gived. To make the simulation closer to the real situation, further improvements was made. Vehicle control and Vehicle load module were added according to the true electric vehicle power system components. Compared with bang-bang DTC, sliding mode DTC obtain a better torque control performance.In order to further research direct torque control theory, to establish a physical lab environment is necessary. At the end of this paper, a motor driver and the software of motor controller was designed. On this basis, a dynamometer-based test system used in permanent magnet synchronous for electric vehicle motor is established. Now, most of the features of the experimental system have been achieved.