A Novel Design of Traction Control Based on a Piecewise-Linear Parameter-Varying Technique for Electric Vehicles With In-Wheel Motors

This paper presents a novel piecewise-linear robust traction controller for electric vehicles with in-wheel motors. Considering the nonlinear tire force and the time-varying wheel and vehicle speeds, a piecewise-linear parameter-varying (PWLPV) slip-ratio model with disturbances is first established. A novel traction controller is then designed. The key of the traction controller proposed in this paper is to separate the traction torque into a feedforward control torque and a PWLPV feedback control torque to track the desired slip ratio. The feedforward controller is calculated through the desired working point of the PWLPV slip-ratio model. The PWLPV controller can guarantee the closed-loop stability and H∞performance for disturbance rejection. To verify the effectiveness of the proposed traction controller, both simulations and experiments are performed. A high-fidelity vehicle model in veDYNA is employed for simulation studies. Experiments were carried out on an electric vehicle with in-wheel motors. The experimental tests were performed on a brake-measurement track at Nong'an Automotive Proving Ground of the First Automobile Works.