The driving motor of the electric vehicle (EV) can recover kinetic energy during normal braking maneuvers by regenerative function. At the same time, its dynamic torque response proves to be accurate and fast for emergency braking, namely anti-lock braking, with coordinated control of the frictional braking system. However, vehicle transmission properties will deteriorate control performance of the motor, especially in the anti-lock braking process. A novel PMSM control method is proposed considering the transmission influence on this high-dynamic braking process of the pure electric vehicle. Firstly, the EV's dynamic model which includes the PMSM field oriented control (FOC) model, the transmission dynamic model and the hydraulic braking system is built, and the influences of transmission elasticity and backlash non-linearity on motor braking torque are analyzed. Then, based on the wheel slip ratio target of the anti-lock braking, the novel mode-switching method for motor torque control between the backlash sliding-mode compensation and the elasticity double-closed-loop PID compensation is put forward. Two state-of-the-art anti-lock braking algorithms which simplify transmission properties, slip ratio phase plane theory and sliding-mode control, are compared with the proposed method. Simulation and test-bench experiment results show that, on different test road surfaces, the mode-switching PMSM control can effectively compensate for transmission effects and significantly improve the EV's anti-lock braking comfort, stability and maneuverability with fast and accurate motor torque regulating.

This paper presents a novel dynamic load emulation methodology applied in the three-motor test bench of the electric vehicle (EV), which can reproduce the motion states of the electric drive/brake system (EDBS) with high precision in longitudinal dynamics processes. First of all, the dynamics models of a front axis drive electric vehicle and a three-motor test bench are established. On the basis of the existed model, a novel dynamic load emulation strategy, which utilizes an adaptive sliding mode controller (ASMC) with an extended state observer (ESO) for speed tracking of each loading electric dynamometer and adopts the cross-coupling control scheme and an adaptive sliding mode speed synchronization controller to attenuate the load emulation error resulting from the unsynchronized rotational angular velocities between the two loading machines. The entire load emulation system has strong robustness and can reject the external disturbances coming from the vehicle motor and system parameters vibrations. Simulations are carried out in MATLAB/Simulink to verify the validity of the newly proposed control law, and results show that the novel load emulation strategy can reduce the load emulation error and eliminate the synchronous error significantly compared with the conventional parallel PI control.