A Novel Series Magnetic Circuit Variable Flux Memory Machine With Self-Flux Leakage Paths
Xianxian Zeng, Heyun Lin, Hui Yang, Yuxiang Zhong, Wei Liu, Xifang Zhao
Abstract
Variable flux memory machine (VFMM) applying low coercivity force (LCF) permanent magnets (PMs) is suitable for electric vehicles (EVs) since its air-gap flux can be adjusted easily. In this article, a novel series magnetic circuit VFMM with self-flux leakage paths (SMC-VFMM-SLP) is proposed, in which the design concept of self-flux leakage is introduced to enhance air-gap flux regulation (FR) range and keep high torque density simultaneously. The self-flux leakage paths can control the self-flux leakages based on the magnetization states (MSs) of the employed LCF PMs. The machine can thus keep a high torque density under the positive MS and achieve excellent flux-weakening ability under the negative MS when it is loaded. First, the topology and the FR range expansion principle of SMC-VFMM-SLP are interpreted in detail, in which the magnetic circuits under different MSs are qualitatively analyzed. The electromagnetic performance of SMC-VFMM-SLP under the positive and negative MSs is subsequently investigated by the finite element method, including no-load characteristics, torque abilities, and efficiency maps. Finally, an SMC-VFMM-SLP prototype is manufactured and measured, which confirms the feasibility of the proposed self-flux leakage paths design for the air-gap FR range improvement.