Comparative Study on the Electromagnetic Characteristics for Pole-Slot Combination of Axial Flux Permanent Magnet Synchronous Motor with Fractional Slot Concentration Winding

Since both the winding factor and machine period depend on the pole-slot combination, their selection has a significant impact on the electromagnetic characteristic of electrical machine, including cogging torque, torque ripple, and efficiency during machine design. In this paper, the electromagnetic characteristics of the axial flux permanent magnet synchronous motor are analyzed for the pole and slot combination which has the fractional slot concentrated winding. Four different pole-slot combinations are selected to compare the electromagnetic characteristics. The winding factor, which influences torque and torque ripple, and the least common multiple of the poles and slots number, which affects the cogging torque, are compared with four pole and slot combinations. Based on finite element analysis, the no-load and load characteristics are compared, and the favorable pole-slot combination is identified with respect to toruqe characteristics and efficiency.