Optimum design of SPMSM with concentrated windings and unequal tooth widths for EPS

Cogging torque and torque ripple of surface-mounted permanent magnet synchronous motor applied to electric power steering (EPS) have been one of the main concerns in manufacturing the EPS system. A variety of methods have been suggested to minimize cogging torque and torque ripple. However, this paper presents 2 different types of the motor and a comparative result from their characteristic analyses using finite element method. Both are composed of 8 poles/12 slots with concentrated windings while one have equal tooth widths and the other unequal tooth widths. Furthermore, it is scarcely possible to induce equations which express the relations among the 4 design parameters, eccentricity, angle between tooth tips, small tooth width, and pole arc. Therefore, this paper purposes optimization of unequal type for EPS motor through response surface methodology.