Coordination Control Of Four In-wheel Motors Driving EV

Electric vehicles as the mainstay of new energy vehicles, with easy manipulation, zero pollution, low noise, and low maintenance and operating costs, alleviate the pressure of energy shortage and environmental pollution in the world. Compared with the traditional fuel vehicles, electric vehicles have the incomparable superiority in environmental protection and saving energy, especially in-wheel motors driving electric vehicles, with excellent control performance and simple structure characteristics, become a dark horse in electric vehicle industry. Thus, the electric vehicles will be the development direction of the global auto industry.First, this article introduces the development background of the electric vehicles, as well as significance of the research, analyzes the performance requirements of motors for electric vehicles and the advantages of using in-wheel motors. By comparing the advantages and disadvantages of all kinds of alternative motors, finally select permanent magnet synchronous motors as in-wheel motors for EV.Second, establish the mathematical models of permanent magnet synchronous motor in different coordinates, introduce the basic control methods of permanent magnet synchronous motor, after comparing every control algorithm, select direct torque control method with the advantages of fast response, simple algorithm and small impact on the motor parameters. Based on the principle of DTC structures, build the model of simulation, realize the control of single in-wheel motor in this topic.Third, on the basis of controlling single motor, conduct a detailed study of multi-motor synchronous control. Introduces the basic concepts of multi-motor synchronous operation, the methods of multi-motor synchronous control include concurrency control, master-slave control, electronic virtual axis control, cross-coupled control, and deviation coupling control. By analyzing and comparing the five methods, use the deviation coupling control strategy to realize synchronous operation of four motors, establish simulation model of multi-motor deviation coupling synchronization control system, study synchronous operation of four motors when EV travels straight.Forth, in order to improve the performance of control system, combine the traditional PID control which has simple structure and good reliability with fuzzy control which has good robustness, a fuzzy PID controller provides speed compensation for the system, realize self-tuning of parameters in the PID controller, improve the control precision and stability of the system, reduce the following error and synchronization error of the system. In the Matlab/Simulink, design the model of a fuzzy PID speed compensator, establish simulation model of multi-motor deviation coupling synchronization control system based on fuzzy PID speed compensator, imitate synchronous running state of four in-wheel motors in the electric vehicle.In the end, applying differential steering strategies which is based on Ackerman model and direct torque control of PMSM to the electronic differential steering system of electric vehicle is to realize the electric vehicle differential drive. Through the simulation, the method is proved to be feasible and effective.