Torque allocation of four-wheel drive EVs considering tire slip energy

With the increasing peak torque of the in-wheel motor, the tire slip energy dissipation becomes as considerable as the motor energy loss. The actuation redundancy in four-wheel drive electric vehicles has the innate advantage of reducing the energy dissipation of the tire slip according to different criteria. This study innovatively optimizes the energy loss of the motor and the slip energy consumption of the tire under a unified framework. A more accurate calculation model of the tire slip force and slip energy is adopted in the cost function. Its feasibility and potential are shown through simulation case studies based on different road adhesion coefficients among three allocation methods: considering both motor energy loss and tire slip loss, only considering the motor energy loss, and only considering the axis load distribution. The simulation results demonstrate that the torque allocation method considering both motor energy loss and tire slip loss can dramatically reduce the tire slip energy and tire wear with an acceptable motor energy efficiency sacrifice compared to the present allocation algorithms.