Torque Component Redistribution and Enhancement for Hybrid Permanent Magnet Motor with Permanent Magnet Offset Placement

In this article, a hybrid permanent magnet (PM) motor with offset placement design is proposed. In the proposed design method, the center axes of rare-earth PM and nonrare-earth PM are shifted artfully to improve motor performances, including output torque and antidemagnetization capability. The relationship among the PM offset placement, current angle, and electromagnetic performances is established. In order to reduce the current angle to achieve maximum output torque, the PM shift angle is preliminarily designed. To further improve motor performances, a multiobjective optimization approach is subsequently carried out for optimal motor design. In addition, to demonstrate the advantages of the PM offset placement, a symmetric placement PM motor is included to be compared with the proposed offset-placement hybrid PM motor based on electromagnetic characteristics. Finally, a prototype motor is built and tested. Based on simulation and experimental results, it is proven that the PM offset design can improve motor performances while it provides a new research path for hybrid PM motors.