회전자 편심과 극호비를 이용한 EPS용 전동기의 코깅 토크 저감 최적설계

Abstract

This paper presents optimum design process for minimizing cogging torque of EPS motor using appropriate rotor eccentricity and pole arc to pole pitch ratio. Improvement of driver’s steering feeling can be achived by optimizing motor in EPS system because motor is directly connected to driver through steering wheel. Considering that motor is mainly operated in low speed region, primary objective function of this optimization is cogging torque. Several design parameters have been researched to reduce cogging torque. Rotor eccentricity can be determined solely by eccentricity length and if number of poles is decided, pole arc to pole pitch ratio is determined only by pole arc. With their design simplicity, those two design parameters are selected to minimize cogging torque. Statistical method, Response Surface Method(RSM) is used in this paper because relation between cogging torque and two design parameters cannot be investigated mathematically. Considering average torque and torque ripple additionally, optimum design was performed.