Research On Variable Idle Speed Control For Electric Vehicle In-wheel Motor

With the rapid development of electric vehicles, a number of advanced driving and control methods came out. In-wheel drive, as one of the most popular driving method, has greatly improved the efficiency of the transmission system. However, the rigid connection between hub and wheel-motor brings great electromagnetic impulse and mechanical shock, which is harmful to the battery and control system, especially in urgent starting and braking. Furthermore, an awful driving experience is inevitable.In an internal combustion engine vehicle, a clutch is used to release the impact of starting and shifting. Referring to the principle, a novel bistable PM electromagnetic clutch for wheel-motor is developed to separate the starting process of the motor and the vehicle. In this way, the electromagnetic impulse and mechanical shock is obviously relieved. In the thesis, some research is done on optimal idle speed control for electric vehicle, and starting with clutch can be named as flexible start, corresponding to direct start.Firstly, a mathematical model for flexible start is built. With the help of MATLAB/Simulink, the starting process is simulated and the performance of direct start and flexible start is compared. The simulation result shows that flexible start is effective for reducing the electromagnetic impulse and mechanical shock.Secondly, in order to find the optimal idle speed under different load conditions, more simulations for variable idle speed control are done, and a scheme for optimal idle speed control under different load conditions is proposed.Finally, a test platform for flexible start is constructed. Compared with the simulation result, flexible start strategy is further proved to be feasible and advanced.