Low Torque Ripple Rotor Design of the Interior Permanent Magnet Motor Using the Multi-Phase Level-Set and Phase-Field Concept

This paper proposes a new optimization method to design the rotor of interior permanent magnet (IPM) motor which consists of a permanent magnet (PM) and ferromagnetic material (FM) for reducing the torque ripple. To express three different material properties (PM, FM, and air), a multi-phase level-set model representing two level-set functions is introduced and the concept of a phase-field model is incorporated to distribute level-set functions for controlling the complexity of the structural boundaries. The optimization problem is formulated to minimize the torque ripple under the volume constraints of each material. Two level-set functions are updated with their respective design sensitivities. To verify the usefulness of the proposed method, the rotor design example of the IPM motor is performed and a novel configuration is obtained.