Wheel Torque Distribution Control Strategy for Electric Vehicles Dynamic Performance With an Electric Torque Vectoring Drive Axle

The ability of active chassis control for dynamic performance improvement of electric vehicles with a centralized drive system is limited due to the driving torque between two-side wheels always equally distributed. To solve this problem, this article proposes a novel electric torque vectoring (TV) drive axle and its torque distribution control strategy, which can realize the function of arbitrary distribution of the left wheel (LW)/right wheel (RW) driving torque in the form of centralized drive, thereby improving the dynamic performance of the vehicle. First, the structure and the torque distribution principle of TV drive axle are analyzed theoretically. Subsequently, an accurate mathematical model of TV drive axle is established based on bond graph theory. Next, a wheel torque distribution control strategy of TV drive axle is proposed based on a hierarchical control approach to improve the vehicle's handling stability. Wherein, the target yaw rate motion tracking controller as the upper-level controller is designed based on the second-order super-twist sliding mode control (SS-SMC) algorithm, and the wheel drive anti-slip controller in lower level is used to restrict possible wheels slipping. Finally, the offline simulation and hardware-in-the-loop (HIL) experiment results suggest that the proposed novel TV drive axle and control strategy can significantly improve the handling stability and steering flexibility of the vehicle.