Optimal Design of Stator of Permanent Magnet Motors Having Closed Slot For The Cogging Torque Reduction

폐슬롯 형상을 가진 영구 자석형 동기 전동기의 코깅 토크 저감을 위한 고정자 치수 최적화

This paper presents the cogging torque analysis of the permanent magnet type AC servo motor which have the closed slot structure. Generally, existence of the slot opening causes the cogging torque. But the cogging torque exists in this type motor(having closed slot structure) because the bridge part is saturated by the rotor flux. In this paper, the finite element analysis is used to calculate the cogging torque and the rated torque. As the size of the bridge part-the thickness and the width-changes, the cogging torque and the rated torque are obtained repeatedly like as upper procedures. Finally, the trends of the cogging torque and the rated torque versus the size of the bridge part are obtained from this analysis procedures. By this approach, the optimal geometry of the bridge part can be found which minimize the cogging torque satisfying the required value of the rated torque.