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 effects are applied. However, SAPMVM suffers from a considerable torque reduction due to the deteriorated low order working harmonic caused by flux barrier effects. 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 magnet bridge is introduced, which can effectively restrict the flux barrier effects. As a result, both the working 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 33% and 113% under rated-load when the PR is selected as 5 and 11.