Research On A Mixed Control System For AC Asynchronous Drives Of EV

With the development of science technology and the improvement of standard living, the vehicle has played the more and more important role in the people's lives. The sharp increase of vehicle quantity brings great convenience to people's lives, but at the same time, it also brings energy crisis and environmental pollution and other serious negative effect to the social. In order to solve the negative effects of fuel vehicles, electric vehicles (EV) will be the future development tendency of automobile. The core technology of the EV is the motor control, what's more in recently, the main control technology includes field orientation control (FOC) and direct torque control (DTC), and these two kinds of method is more advanced. By reading a lot of literature and doing a series of experiments, then people found that the two methods have their own advantages and disadvantages, and these two kinds of theory is not very perfect for controlling induction motor. Some scholars at home and abroad have been made some work to improve these two methods, but it may increase the complexity of the control system or changed the system itself with some advantages. What's the worse Some of the changes in the actual project application can not be achieved.An innovative control strategy, which is an organic combination of the two schemes, is presented in this paper to adopt the other's strong points to offset one's weakness based on the researching of the asynchronous motor mathematical models and control theory.In order to meet the requirements for EV in the different conditions of torque and speed. So make these two kinds of control method can combine together organicly and can reallize high performance motion control. The system in switching process induce status mutation and oscillation beacause of the theory and control objectives is different between these two konds of method should be solved firstly. For smooth switching between DTC and FOC, a new"resetable"PI controller is designed to replace the conventional PI controller in the paper. Simulation and experiments show that the new"resetable"PI controller can remarkably reduce the fluctuation of mixed control system, and the smooth transition is guaranteed no matter in steady state or transient state, while maintaining the control performance of DTC and FOC. At the same time, according to the conditions of the motor the control system can automatic switch to the control method, so that the motor can run in the best condition. Then the EV can execute the people's command fastly and smoothly.The Matlab simulition will be designed to study the feasibility of the hybrid control method firstly. Then DSP2812hardware circuit is designed. Next, the tool of the connection between the Matlab and DSP is used to design and generation the hybrid control C language program,which is compiled, downloaded and debuaged to control a small power ansynchronous squirrel cage motor.