Simulation And Research On Electric Differential System Of Electric Vehicle With Dual Motors

With the growing problems of environmental pollution and energy crisis, governments, enterprises and scientific institutions pay more and more attention to EV. Because of the simple structure, high efficiency transmission, each wheel can be controlled independently, the EV based on in-wheel motor draw more attention. However, with more freedoms to be controlled, there also exists coordination problems of driving wheels, namely electonic differential(ED) problem. In order to solve it, this paper propose a newly ED system with the aim of improving the vehicle handling and safety.Firstly, a 8-DOF vehicle model is established in this paper as the platform for ED system design. Then a ED system is designed based on slip rate and yaw rate, which includes three main modules: the slip rate control module based on sliding mode control, the yaw motion control module based on based on fuzzy control and the coordinate control module. Finally, accelerated test on the low adhesion road, joint road, and bisectional road, and handling test are designed to evaluate the ED system’s control effect. The simulation results show that, the newly ED system not only realizes the basic antiskid function, but also improves the vehicle handling and stability.Considering the limitations of side-slip angle control, 4WS system is introduced to integrate with the ED system, so that the side-slip angle and the yaw rate are able to be controlled simultaneously by regulating longitudinal force and lateral force. 4WS controller is designed with the integration of feedforward control and feedback control to control the side-slip angle by regulating the steering angle of the rear wheel. Then, a coordinate controller is built to harmonize the ED system and the 4WS system. The simulation results show that, compared with the ED system, integrated control system can reduce the side-slip angle with the improvement of vehicle handling and safety, especially, when the EV is travelling at a low speed or a moderate speed, the side-silp angle can be controlled approximately zero, which contributes to trajectory tracking.