A Novel Asymmetric V-Type Variable Flux Memory Machine With Hybrid-Layer Permanent Magnets

In this paper, a novel asymmetric V-type variable flux memory (VFM) machine featuring a hybrid-layer permanent magnet (PM) structure is proposed. This design incorporates two PM arrangements within each pole: one part employs a single-layer variable PM (VPM), while the other part features a dual-layer PM arrangement consisting of a constant PM (CPM) and a VPM. The proposed machine, along with two existing machine topologies: a symmetrical single-layer VFM machine and an asymmetric single-layer VFM machine, is optimized using finite element method with the same stator, rotor diameter, and total PM usage. The electromagnetic performance of the optimized designs for all three machines is investigated and compared. It shows that the asymmetric design can mitigate the intrapolar cross-coupling effect between the CPMs and VPMs found in the symmetrical VFM machine, thereby delivering higher torque output. Furthermore, compared to the asymmetric single-layer VFM machine, the proposed machine can achieve wider flux regulation range and improved overall efficiency due to the series-parallel magnetic circuit enabled by the hybrid-layer structure. Finally, a prototype of the proposed machine is fabricated and tested for validation.