A new coaxial magnetic gear using stationary permanent magnet ring

This paper proposes a new topology of coaxial magnetic gear (CMG) using stationary permanent magnet ring (PMR) between the permanent-magnet (PM) inner rotor and the salient-pole outer rotor without PMs, aiming at improving the robustness of the outer rotor while the torque density is maintained. The fundamental operation of the proposed topology is the modulation of the magnetic field produced by the PMR due to the outer-rotor salient poles, such that appropriate harmonics having the same number of poles as the PM inner rotor can be produced in the inner airgap. By using the finite element method (FEM), the airgap flux density and static characteristics of the proposed CMG are analyzed. Moreover, a quantitative comparison between the conventional CMG and the proposed one is conducted to verify the validity of the proposed design.