Analysis of Leakage Flux in Fractional-slot Axial Flux Permanent Magnet Machine with Different Slots and Poles

Axial flux permanent magnet (AFPM) machines have larger leakage flux than the traditional radial flux PM machines. In this paper, the air-gap and tooth-tip leakage flux of AFPM machines with different slots and poles are analyzed and researched. Firstly, the air-gap leakage coefficient is derived based on the equivalent magnetic circuit (EMC) model with different slot and pole combinations. Then, the tooth-tip leakage coefficient is calculated by using the analytical method (AM), and compared with the finite element method (FEM). In addition, the influence laws of parameters on the different leakage coefficients are analyzed. Finally, the leakage flux of different slots and poles are compared based on the proposed method, the results show that the fractional-slot AFPM machine with fewer poles and more slots have a lower leakage coefficient.