Design Concept and Performance Analysis of Dual-Variable Flux Memory Machines for Traction Drive

This article proposes the design concept of a dual-variable flux memory machine (D-VFMM) with hybrid permanent magnets (PMs), in which both PM flux and leakage flux are variable. By reasonably controlling the two variable fluxes, the inherent contradiction between the high torque density and wide speed operating range of variable flux memory machines (VFMMs) can be readily solved. This article presents the design concept of this kind of machine by taking a new series magnetic circuit D-VFMM for electric vehicles (EVs) as an example. The superiorities of the dual-variable flux concept are illustrated through a comparative analysis between the proposed machine and a traditional VFMM under specific magnetization states (MSs). The electromagnetic performance of the designed machine across varying MSs is comprehensively analyzed by the finite element method. Finally, a D-VFMM prototype designed according to the presented concept is manufactured and tested. Experimental results validate the superiority of the presented design concept and the feasibility of the prototype for driving EVs.