Design and Investigation of a New Variable Flux Memory Machine with Self-Flux Leakage Path

Abstract

Variable flux memory machine (VFMM) with a wide speed range and a high efficiency has potential application in electric vehicles (EVs) because the magnetization state (MS) of the employed low coercivity force (LCF) permanent magnets (PMs) can be flexibly adjusted by applying a short time current pulse. However, it is very difficult for existing VFMMs to balance their torque output capacities and wide speed operation abilities. In this paper, a new hybrid magnetic circuit (HMC) VFMM with self-flux leakage paths is proposed to improve the torque density and extend the magnetic flux regulation range simultaneously. The topology and flux regulation principles of the proposed machine are described and interpreted. The electromagnetic characteristics of the machine under different MSs are comprehensively analyzed. The finite element results indicate that the proposed machine possesses a satisfactory output torque and a wide speed range since the self-flux leakage paths work only in the demagnetization state.