Multi-physics Analysis of Surface Inset Permanent Magnet Motors with Different Slot-Pole Combinations

This paper deals with the multi-physics analysis of surface inset permanent magnet (PM) motors with different slot-pole combinations. Five surface inset PM motors including 24-slot/4-pole (4p24s) integral-slot distributed-winding (ISDW), 27-slot/6-pole (6p27s) fractional slot distributed winding (FSDW), 6-slot/4-pole (4p6s), 9-slot/8-pole (8p9s), 12-slot/l0-pole (10pl2s) fractional slot concentrated winding (FSCW) are designed with the same specifications and analyzed utilizing the finite-element method (FEM). Firstly, the electromagnetic performance is analyzed, including cogging torques, torque characteristics, magnetic and reluctance torque ripples. Then, the electromagnetic vibration and noise are studied through two-dimensional (2D) decomposing of radial force density and modal analysis of stators. Finally, the vibrations under different speeds are discussed. It is concluded that cogging torques of the FSCW motors (8p9s and 10pl2s) are significantly suppressed. The torque characteristic results show that the reluctance torques of distributed winding motors (4p24s and 6p27s) account for a larger proportion of total torques than that of the other three motors. According to the study of magnetic and reluctance torque ripple, the fractional slot motors are better than the integral-slot motors. The vibration and noise analysis results show that the distributed winding motors (4p24s and 6p27s) have lower vibration.