Integrated traction control strategy for 4-motorized-wheels electric vehicles with improvement of economy and longitudinal driving stability

This paper presents an integrated traction control strategy (ITCS) for 4-motorized-wheels electric vehicles. The purpose of this proposed strategy is to improve vehicle economy and longitudinal stability. On high adhesion roads, economy optimization algorithm is applied to maximize motors efficiency by means of the optimized torque distribution. On low adhesion roads, sliding mode control (SMC) algorithm is implemented to guarantee the wheel slip ratio under the target slip ratio to make full use of road driving capacity. Since the optimal slip ratio on different road conditions varies a lot, a quasi-optimal slip ratio is introduced and set as the target value. The integrated traction control strategy is designed for combining the vehicle economy and longitudinal stability via three torque allocation cases: economy-based torque allocation, pedal self-correcting torque allocation and inter-axle torque allocation. Finally, simulation results show that the proposed strategy effectively reduces vehicle energy consumption, suppresses wheel skid and enhances the vehicle longitudinal driving performance.