Design and analysis of a flux-decoupling magnetic-geared permanent-magnet brushless machine

This paper investigates a new direct-drive machine, which artfully integrates a permanent-magnet brushless machine (PMBM) into a magnetic gear (MG). In order to achieve the capability of low speed operation and high torque output, the PMBM and MG share the same high-speed rotor. The key of the proposed machine is to adopt the Halbach permanent-magnet (PM) arrays and employ them to compose the PM poles on both sides of the integrated rotor, which makes the inner PMBM field and the outer MG field decoupled. Furthermore, the merits of high gearing ratio, low cogging torque, high efficiency, and excellent electromagnetic performance, can be incorporated, which are also calculated and analyzed by using finite element method (FEM). Eventually, the prototype of the proposed flux-decoupling magnetic-geared PMBM machine is built up. The corresponding results verify the theoretical analysis and the machine design.