Surrogate-based auxiliary slot optimization for a fractional slot IPM machine used in the public transportation

Abstract

This paper focuses on the application of electrical machines in public transportation and investigates the potential benefits of auxiliary slot design on this kind of high-speed low torque machine. A preliminary surrogate-based optimization is conducted to the shape of auxiliary slots on the stator for minimizing its cogging torque ripple while maintaining its Total Harmonic Distortion (THD) at an acceptable level. The results show the optimization achieves its best performance while the edges of the auxiliary slot are parallel to the edges of the stator teeth, which could reflect a deeper resonance among the geometries of the stator magnetic field.