Sources of power loss during torque--vectoring for fully electric vehicles

Continuous wheel torque control of fully electric vehicles (FEV) offers potential improvements in vehicle dynamics and energy efficiency. Various studies have shown benefits from torque–vectoring for minimising vehicle power consumption by considering the losses from the electric motor drives. However, during vehicle operation, various sources of power loss exist such as dissipations due to longitudinal and lateral tyre slip which are strongly influenced by the wheel torque control system. In this study, the different power loss types during steady–state and transient manoeuvres of a case study four–wheel–drive FEV are quantified. The motor drive losses are a major contributor at low lateral acceleration but represent a secondary factor at significant lateral acceleration at which the tyre slip power losses are the most significant contribution. Future control allocation methods seeking to reduce power consumption should consider tyre slip in addition to actuator losses.