Comprehensive Study of Variable Flux Memory Machines with Symmetrical Series Hybrid Permanent Magnets in Rotor Pole

Abstract

Variable flux memory (VFM) machines with symmetrical series hybrid permanent magnets (PMs) structures in rotor pole, evolved from Prius IV MG2 machine (Prius IV), are analyzed and compared in this paper. The reluctance torques are maintained in all magnetization states of Prius IV memory machine (Prius IV-M) due to the series hybrid PMs magnetic circuit. Firstly, the influences of positions and volume ratios of variable PMs (VPMs) and constant PMs (CPMs) on the available flux variation range of Prius IV-Ms are investigated based on the limit of maximum pulse current. Then, the electromagnetic performances of Prius IV-Ms with ideal, demagnetization and re-magnetization states are further investigated based on the case with the volume ratio of VPM/CPM as 1:2 and compared with Prius IV. The Results also show that Prius IV-M exhibits lower efficiency than Prius IV over the whole efficiency area except in the extremely low torque low speed area.