Rotor-Shape Optimization of Interior-Permanent-Magnet Motors to Reduce Harmonic Iron Losses

In this paper, we develop novel rotor designs of interior-permanent-magnet motors in order to reduce harmonic iron losses at high rotational speeds under field-weakening control. First, an optimization method, combined with an adaptive finite-element method, is applied to automatically determine the shapes of the magnets and rotor core. The optimized motor is manufactured to confirm the validity of the calculation. It is clarified that the iron loss of the optimized motor is reduced to nearly half of that of the conventional motor, without a significant decrease in maximum torque. Next, the contribution of each part of the rotor to the iron-loss reduction is analyzed by the experimental design method. Finally, several designs of the rotors are proposed from the viewpoints of manufacturing cost and performance.