Analysis of a Flux Reversal Machine With Quasi-Halbach Magnets in Stator Slot Opening

Flux reversal permanent magnet (FRPM) machine, with magnets mounted on or inserted into the stator, is favorable for the direct drive applications. In this paper, an FRPM machine with Quasi-Halbach array magnets in stator slot opening is introduced. The operation principle of the proposed machine is presented, and the combination of stator and rotor slot number is given. Several key parameters, that are split ratio, stator and rotor slot opening ratio, magnet ratio, and magnet thickness are carefully investigated, while four proposed FRPM machines with 12 stator slots and 10, 11, 13, 14 rotor slots are optimized for better performance. Moreover, the proposed FRPM machine is compared with a conventional FRPM machine, the analysis results indicate that the torque density of proposed machine is 2.2 times that of the conventional FRPM machine under the same copper loss with almost the same magnet usage. Finally, a 12 stator slot/10 rotor slot FRPM prototype is built to verify the theoretical analysis.