Design of a new magnetic-planetary-geared outer-rotor permanent-magnet brushless motor for electric vehicles

In this paper, a new type of in-wheel motor for electric vehicles (EVs), namely magnetic-planetary geared outer-rotor permanent-magnet brushless (PMBL) motor is proposed. The key is to incorporate the concept of the non-contact magnetic planetary gear into a permanent magnet brushless machine. Thus the resulting machine can achieve ability of match between the high speed motor and the relatively low speed wheel, and therefore can obtain high power density, high efficiency and small size as well. The machine topology and operation principle are presented in details. By using the time stepping finite element method, the electromagnetic performances of the proposed machine are analyzed accurately. Finally, efficiency and loss of the machine are simulated to evaluate the proposed machine. Both theoretical analysis and simulation results show that the proposed machine can realize the functions of direct drive motor, and thus, is an interesting candidate for advanced EVs.