Conference: 2026 한국자동차공학회 춘계학술대회
Authors: 김규빈, 곽병길, 임명섭
DOI:
Variable flux memory machines (VFMMs) have attracted significant research interest as a promising alternative to conventional permanent magnet synchronous motors, since active control of the magnetization state (MS) of low coercive force (LCF) permanent magnets enables flexible air-gap flux adjustment, alleviating the copper loss increase associated with conventional flux-weakening control. However, the electromagnetic characteristics of VFMMs are strongly governed by the magnetic circuit coupling configuration between high coercive force and LCF magnets, resulting in distinct trade-offs among the flux adjustment (FA) range, on-load MS stability, and magnetizing/demagnetizing current requirements. In this paper, three VFMM topologies — series (SMC), parallel (PMC), and hybrid magnetic circuit (HMC) — are designed and compared through equivalent magnetic circuit analysis and 2D finite element analysis. The results show that PMC achieves the widest FA range but with inferior MS stability, while SMC demonstrates excellent unintended demagnetization (UD) withstand capability but limited FA range. HMC simultaneously achieves a comparatively wide FA range and superior UD withstand capability, exhibiting the most balanced electromagnetic characteristics. Based on these findings, rotor design guidelines are provided for optimal VFMM topology selection according to target operating requirements and performance priorities.