Topological Principle and Electromagnetic Performance of a Novel Axial-Flux Hybrid-Excitation In-wheel Motor

In order to solve the problems of poor flux-weakening capacity and unsatisfactory overall efficiency of the axial-flux permanent magnet (AFPM) machines with surface-mounted PM rotor structure, a new axial-flux hybrid-excitation machine (AFHEM) topology with double consequent-pole rotors and sandwiched stator is proposed and developed for in-wheel motor driven electric vehicle. The unique external rotor construction and operation principle of the AFHEM are discussed. The equivalent magnetic circuit model with bidirectional excitation is analyzed. The finite-element analysis (FEA) for electromagnetic design and analytical prediction of electromagnetic performance is performed extensively, which verify the effectiveness of the new topology of hybrid excitation in-wheel motor for wheel hub integration.