In order to research stability of four-wheel independent driving (4WID) electric vehicle, a torque allocation method based on the tire longitudinal forces optimization distribution is adopted. There are two layers in the controller, which includes the upper layer and the lower layer. In the upper layer, according to the demand of the longitudinal force, PID controller is set up to calculate the additional yaw moment created by yaw rate and side-slip angle. In the lower layer, the additional yaw moment is distributed properly to each wheel limited by several constraints. Carsim is used to build up the vehicle model and MATLAB/Simulink is used to build up the control model and both of them are used to simulate jointly. The result of simulation shows that a torque allocation method based on the tire longitudinal forces optimization distribution can ensure the stability of the vehicle.

This paper describes in detail three kinds of typical compound braking strategy of wheel motor drive electric vehicle and summarizes the current commonly used strategies based on the three typical strategies developed. In the end, a new compound braking strategy is proposed; that is, we take braking mode classify, ECE regulations and SOC value of the battery as an important reference of braking force that joins the motor braking force, as well as we join the different identification models; according to the different braking modes, the purpose is that we can apply the different braking program.