Shape Optimization of Tooth and Yoke in Interior Permanent Magnet Motor for Maximizing Torque

Interior permanent magnet(IPM) motor has been widely used in the automotive industry and it needs high torque performance due to the limitation of the hybrid or electrical vehicle battery capacity. Torque can be improved by adjusting the tooth and yoke and it can be defined as shape optimization problem. Previous researches are restricted to the parametric optimization so that it cannot produce the innovative design. This paper proposes the optimal shape of tooth and yoke using level set-based optimization method since it provides flexibility to represent boundaries. The material properties of ferromagnetic material and coil current are defined by level set function with Heaviside function. The optimization problem is formulated to maximize the torque under the material usage constraint and the shape boundaries are moved by the normal velocity derived from the optimality condition. To validate the proposed method, it is applied to the traction motor design of the hybrid vehicle and produced the innovative configuration