Novel asymmetric variable flux memory machines with U-type PM configurations

Abstract

In this paper, two novel asymmetric variable flux memory machines with U-type permanent magnet (PM) configurations are proposed. These designs feature variable PMs (VPMs) placed on one side and constant PMs (CPMs) on the opposite side of the U-shaped cavity, with or without additional VPMs in the middle cavity. Both machines are firstly designed and optimized using finite element method with the same 21-slot/4-pole stator and rotor inner/outer diameters. The electromagnetic performance of the optimized designs are analyzed and compared. Results show that the middle VPMs can enhance the flux regulation (FR) capacity but contribute less to the torque. As a result, the machine with the middle VPMs can achieve a wide FR range and improved overall efficiency, whereas the machine without the middle VPMs can deliver higher torque density. Finally, two prototypes are fabricated and tested for validation.