Torque Quality Enhancement of a Multi-Permanent-Magnets Motor Considering Different Role-Plays of Permanent Magnets

In this article, a multi-permanent magnet (multi-PM) motor with a distributed placement of PMs is proposed, considering different role-plays of PMs. The key is to propose a new concept of PM role-play, which can enable different PMs to perform their specific role for torque quality enhancement, i.e., output effective torque improvement and torque ripple suppression. The topology of the multi-PM motor is derived, and the roles of the multiple PMs in air-gap flux density and torque quality are deduced and investigated in detail. Then, the electromagnetic performance of the motor generated by each PM is optimized and evaluated by finite element analysis with the frozen permeability method, including the air-gap flux density, average torque, and torque ripple. Finally, a prototype is manufactured and tested. Experimental results are illustrated to verify the effectiveness of the proposed motor and torque quality enhancement method.