Magnetic Circuit Number Improvement of Novel Multi-Series Magnetic Circuit Variable Flux Memory Machines with Reduced Magnetizing Current

Variable flux memory machines (VFMMs) have attracted wide interest in the field of electric vehicles due to their flexible flux variation (FV) capability. Nevertheless, the existing VFMMs still suffer from excessive remagnetizing or demagnetizing currents and limited FV range, which seriously hinder their potential for widening the speed range and high-efficiency region of VFMM. Addressing this issue, two novel multi-series magnetic circuit VFMMs (MSMC-VFMMs) with different numbers of magnetic circuits are proposed in this article. The proposed configurations can combine the outstanding FV range and the low magnetizing current advantage of multiple magnetic circuit design. First, the special structure and working principle of the proposed MSMC-VFMMs are introduced respectively. Subsequently, the conventional SMC structure and the two derived MSMC structures are modeled based on the equivalent magnetic circuit approach to confirm the wider FV range of the proposed structures. Moreover, the remagnetizing and demagnetizing characteristics of the three VFMMs are thoroughly analyzed, confirming the advantages of the MSMC structures in terms of magnetizing current requirements, especially for demagnetizing operations. Besides, the electromagnetic properties of the three VFMMs are thoroughly analyzed, with the comprehensive performance metrics indicating that the MSMC-II VFMM is more favorable. Finally, an MSMC-II prototype is manufactured and subjected to measurements to confirm the accuracy of the analyses.