A Novel Variable Flux Memory Machine With Magnetic Circuit Complementary Structure

Because of the flexible magnetization state adjustment capability, hybrid-magnetic-circuit variable flux memory machines (HMC-VFMMs) can achieve a wide operating range and overall high efficiency, offering potential candidates for electric vehicles. Nevertheless, the existing HMC-VFMMs still suffer the narrow flux adjustment (FA) ranges, which seriously hinder the potential for efficiency improvements in the high-speed region. This article proposes a novel magnetic circuit complementary VFMM (MCC-VFMM) to enhance the FA range and on-load demagnetization resistance (ODR) capabilities simultaneously. Two different parallel magnetic circuit structures are employed in the proposed MCC-VFMM to significantly enhance its FA range, while the ingeniously complementary layout of the dual-layer PM structure can form series magnetic circuits with fine ODR capability simultaneously. First, the structural evolution and corresponding operating principle of the proposed MCC-VFMM are introduced individually. Moreover, the simplified equivalent magnetic circuit models of the proposed machine and the existing HMC-VFMM are developed to determine theoretically the enhanced FA capability of the proposed MCC-VFMM. Furthermore, a comprehensive comparison of the electromagnetic performance of the HMC- and MCC-VFMMs is investigated utilizing the finite element method. Finally, an MCC-VFMM prototype is tested, thereby confirming the feasibility of the above analysis.