A Novel High Torque Density Spoke-Array Permanent Magnets Vernier Machine With Magnets Bridge

In recent years, permanent magnet vernier machine (PMVM) has drawn more attention due to their high torque density. To further improve torque capability, Spoke-array (SA) PM having better flux focusing effect are applied. However, SAPMVM suffers from a considerable torque reduction due to the deteriorated low order working flux harmonics caused by flux barrier effect. Especially, the higher pole ratio (PR), i.e., the ratio of PM pole-pair to armature pole-pair, the severer torque drop of SAPMVM. In this paper, a novel SAPMVM is proposed, where the magnets bridge is introduced, which can effectively restrict the flux barrier effect. As a result, both the working flux harmonics and torque density of SAPMVM are enhanced. To analyze the operating principle of proposed SAPMVM with magnets bridge, an equivalent magnet circuit model is established. Moreover, the electromagnetic performances of the proposed SAPMVM are compared with regular SAPMVM by FEA, where the torque of proposed SAPMVM has increased by 43.3% and 175.6% under rated-load when the PR is selected as 5 and 11.