A permanent-magnet hybrid in-wheel motor drive for electric vehicles

This paper proposes and implements a new outer-rotor permanent-magnet (PM) hybrid in-wheel motor drive for electric vehicles. Since the proposed PM hybrid motor drive artfully integrates two excitations (PMs and DC field windings) to produce magnetic field, it achieves the ability of a wide rang of flux control, which can offer a very high starting torque for electric vehicles cranking and extend the speed range with constant-power operation, as well as keep high efficiency at a wide speed range. Moreover, its outer-rotor topology makes it naturally connect with the wheel tire, hence makes the whole in-wheel drive system compact and seamless. The circuit-field-torque time-stepping finite element method (CFT-TS-FEM) is developed to analyze the steady-state and transient performances of the proposed in-wheel motor drive. An outer-rotor PM hybrid brushless prototype is designed for verification, which is particularly suitable for battery-powered electric motorcycles.