Effects of Unequal-tooth Stator on Electromagnetic Vibration of Fractional-slot Concentrated Winding Permanent Magnet Motors

This paper investigates the effects of unequal-tooth width stator on radial force harmonics and cogging torque in fractional-slot concentrated winding permanent magnet (FSCW-PM) motors. Firstly, considering unequal-tooth width stator, the cogging torque and radial force are derived analytically through the magnetomotive force-permeance model. The general analytical relationship is revealed for the slot/pole combination and cogging torque and radial force in FSCW-PM motors with unequal-tooth width stator. Subsequently, the effects of the unequal-tooth width stator on the radial force harmonics and cogging torque are verified by finite element analysis (FEA), respectively. Finally, the effects of unequal-tooth width stator on the torque ripple, vibration and cogging torque are validated in FSCW-PM motors through the simulation and experimentation.

I. Introduction

THE fractional-slot concentrated winding permanent magnet (FSCW-PM) motor has attracted much attention in many fields, such as domestic appliances and electric vehicles, owing to its high power/torque density, high efficiency etc. Despite the advantages, the FSCW-PM motors generally suffer from the large electromagnetic vibration and noise, which greatly limits their applications. As has been extensively validated the electromagnetic vibration in PM motors mainly results from the radial component of the electromagnetic force and cogging torque. Among them, the cogging torque will cause the large torque ripple, and the radial force, especially the low-order radial force harmonics, will cause the large vibration and deformation.