Improvement of Electromagnetic Force and Acceleration in an Asymmetrical Star-Delta Winding IPMSM through Stator and Rotor Geometrical Modifications

Asymmetrical star-delta winding interior permanent magnet synchronous motor (IPMSM) is introduced as a capable option in supporting higher torque and lower torque ripple characteristics compared to the symmetrical star-delta winding IPMSM. This is at the expense of having higher radial electromagnetic (EM) force and potential vibration-related concerns including high acceleration. EM force and vibration reduction in the asymmetrical star-delta winding IPMSMs have not been well addressed in the literature so far. In order to improve the EM force and acceleration characteristics of the asymmetrical star-delta winding IPMSM while keeping its developed torque within the desired ranges, various stator and rotor geometrical parameters are defined and are changed individually. A sensitivity analysis is utilized to introduce the most effective geometrical design variables for the highlighted objectives. The reduction in the EM force, through the Maxwell-Stress tensor method, and the acceleration on the outer surface of the motor housing of the improved asymmetrical star-delta winding IPMSM structure over a base asymmetrical star-delta winding IPMSM model are investigated and reported via EM and structural simulations.