Numerical Evaluation of a Concentrated-Winding Variable Flux Memory Motor with a Hybrid Magnet Arrangement

This paper presents a novel variable flux memory motor (VFMM) with a series-parallel configuration that employs a constant-magnetization permanent magnet (CPM) with high coercivity and a variable-magnetization permanent magnet (VPM) with low coercivity. The CPMs in the proposed VFMM are arranged in parallel. Therefore, they share an air gap. Meanwhile, the VPMs are arranged in series with respect to the CPMs, as well as each other. The CPM-induced magnetic field not only reduces the re-magnetizing current for the VPMs but also enhances the torque density. Additionally, it can assist VPMs in resisting demagnetization under loaded conditions. For verification, we compared the performance of the proposed model with that of a series-type model widely applied in VFMMs. The magnetization characteristics were investigated using nonlinear finite element analysis by deriving the VPM load line. Furthermore, the electromagnetic performance under re-magnetization and demagnetization conditions was analyzed.