Magnet Pole Design Improvement of Hybrid-Pole Variable Flux Memory Machines

In this paper, the magnet pole design improvements of hybrid-pole variable flux memory machines (HP-VFMMs) are proposed and investigated. A series of HP-VFMMs with different magnet pole topologies are developed to achieve a well-balanced tradeoff between torque density and flux regulation range. The original topology Model-A features a geometric combination of spoke-type high coercive force (HCF) permanent magnets (PMs) and flat-type low coercive force (LCF) PMs. This configuration can significantly expand the design flexibility of HP-VFMMs, offering a high degree of design freedom. To strengthen the flux regulation and unintentional demagnetization (UD) withstand capability of LCF PM, an improved magnet pole topology Model-B characterized by an integration of V-type HCF PM and flat-type LCF PM is developed. First, the machine topologies and operating principles are introduced, respectively. Then, the design concept for deriving the HCF PM pole from spoke-type to V-type is presented and elaborated based on analytical and finite element (FE) methods. Subsequently, for addressing the manufacturing and mechanical reliability issues arising from the relatively complex rotor topology, a simplified rotor design Model-C is further developed. The effects of HCF PM parameters on key performance metrics are investigated, highlighting the performance enhancement mechanisms, as well as identifying optimal designs. Subsequently, the electromagnetic characteristics of the proposed HP-VFMMs with different hybrid magnet pole designs are evaluated and compared by FE method. Finally, a proof-of-principle machine prototype is manufactured and tested, confirming the feasibility of the proposed design.