Optimal split ratio in Switched Flux Permanent Magnet machines

In this paper, it is shown that the split ratio of stator inner diameter to outer diameter influences the torque density in Switched Flux Permanent Magnet (SFPM) machines more heavily than that of conventional Permanent Magnets (PM) machines, since PM are inserted in the stator for SFPM machines. This paper presents a simplified Magnetic Circuit Analysis(MCA) method to analytically optimize the split ratio in order to maximize torque density of SFPM machines, and the method accuracy is verified by the Finite-Element Method (FEM).