Reduction of Unipolar Leakage Flux and Torque Ripple in Consequent-pole PM Vernier Machine

Abstract

This paper proposes a new consequent-pole permanent magnet vernier machine (CPMVM), which can be regarded as a combination of two conventional CPMVM with opposite polarities. Based on the simplified axial magnetic circuit model, it is verified that the proposed CPMVM can reduce the unipolar leakage flux. In order to reduce the torque ripple of machine and improve the output torque of machine, the flux barrier is placed on the rotor of the proposed machine. Then, the parameters of the proposed CPMVM are optimized and determined. Moreover, the electromagnetic performance, including no-load air-gap flux density, average torque and torque ripple, flux linkage, back-electromotive force, cogging torque, average torque, torque ripple, power factor and loss, is compared with conventional surface-mounted permanent magnet vernier machine (SPMVM) and CPMVM. Finally, it is demonstrated that proposed CPMVM with flux barrier can effectively reduce the unipolar leakage flux and greatly reduce the torque ripple of machine. Also, compared with the SPMVM, the proposed CPMVM with flux barrier saves more than 45% of the permanent magnet material without reducing output torque.