Design of a new outer-rotor flux-controllable vernier PM in-wheel motor drive for electric vehicle

This paper proposes a new in-wheel motor drive for electric vehicle (EV), which utilizes the outer-rotor topology to directly couple with the tire rims and hence removing the mechanical transmission. The key is to use the vernier structure for obtaining the high-speed to low-speed gear effect and achieving the high output torque at low speed operation. Also, the proposed motor drive adopts the DC field winding for performing the flux weakening control at high speed operation. Thus, this new in-wheel motor drive can smoothly operate within the speed range of 0∼1000rpm at different operation modes for EVs. The motor drive and its three-operation modes for EV operation, as well as the steady-state and transient performances are analyzed by using the time-stepping finite-element-method.