Optimal Rotor Structure of Surface-mounted Permanent Magnet Motor for Vibration Reduction

Abstract

This paper presents a new optimization method todesign a rotor structure of surface-mounted permanent magnet(SPM) motor which can reduce the vibration. The optimizationproblem is formulated to minimize both the harmoniccomponents of radial force and the torque fluctuation which aremain factors of motor vibration. To obtain the optimal rotorshape consisting of permanent magnet and ferromagneticmaterial, a multiple level set model is employed to express thestructural boundaries and magnetic properties of each material.The updating process of level set function based on the adjointsensitivity and the time evolutional equation makes possible toobtain the novel rotor configuration of SPM motor. To verify theusefulness of the proposed method, the rotor design example ofSPM motor for electric power steering (EPS) system isperformed.