자기 이방성을 고려한 유도전동기의 자성웨지 형상 최적화

Abstract

Induction motor is considered as an alternative type of a traction motor for hybrid cars due to the lack of rare earth material and ease of manufacturing. However, the magnetic flux ripple in the air gap increases the noise and decreases the motor performance so that the magnetic wedge is used in the stator slot. But the application of isotropic magnetic wedge increases the leakage flux and reduces pull out torque and starting torque. In order to overcome this limitation, an anisotropic magnetic wedge which has different permeabilities with directions is applied and shape design is worked to reduce the leakage flux and the flux ripple in the air gap. This paper proposes the optimal design of the anisotropic magnetic wedge to maximize the pull out torque using material boundaries represented by the level set function are moved by the sensitivity of the objective function. Time-harmonic electro-magnetic analysis is performed and then torque profile and efficiency are evaluated. The proposed method is applied to the reference design problem and validated to improve the design.