Comparative Study of Cogging Torque, Torque Ripple, and Vibration on Stator Tooth Chamfer Types in Permanent Magnet Synchronous Motors

Abstract

The high power density, high efficiency, and wide speed range of permanent magnet synchronous motors (PMSMs) are attractive features. However, the cogging torque and unsuppressed torque ripple of PMSMs degrade torque quality and reliability and cause vibration. This article compares the effectiveness of PMSMs in reducing the cogging torque, torque ripple, and vibration by applying each stator tooth chamfer types: inner eccentricity chamfer, outer eccentricity chamfer, linear chamfer, and circular chamfer. First, stator tooth chamfers were applied to the reference model to confirm the tendency of cogging torque, torque ripple, and electromagnetic force according to the design variables by chamfer types, and it was demonstrated that the chamfer needs to be applied in a way that reduces the harmonics of the air-gap magnetic flux density to improve the performances through finite element analysis (FEA). Next, the optimum design for reducing cogging torque, torque ripple, and electromagnetic force was performed for each stator tooth chamfer types for a valid comparison. As a result, it was confirmed that there are advantageous stator tooth chamfer types based on each performance. Finally, a prototype was fabricated and tested to validate the FEA results of the optimum model for performance comparison.