Eddy Current Loss Reduction in Flux-Modulated-type Magnetic Gears by Unequal Division of Magnets

The development of high-speed motors is progressing to increase the power-to-weight ratio. Additionally, gearboxes combined with high-speed motors are required to enhance their capability for high-speed operation. Flux-modulated-type magnetic gears are suitable for such high-speed applications because of their non-mechanical contact and high torque density. However, eddy current loss in magnets must be addressed under high-speed operation. This paper discusses the effect of magnet division on reducing eddy current loss in magnets of flux-modulated-type magnetic gears using FEM and the prototype magnetic gears. It is demonstrated that the circumferential division is more effective than the axial division in suppressing eddy current loss. In addition, a significant bias of eddy current losses within the same magnet in flux-modulated magnetic gears is observed, and the unequal division of magnets can suppress eddy current losses more effectively than the conventional equal division.