Improvement of Torque and Loss Characteristics for an In-Wheel Permanent Magnet Motor Based on Dominant Airgap Harmonic

In this paper, a 12/14-pole permanent magnet in-wheel motor is studied for potential in-wheel application, and the torque and loss are improved simultaneously based on designing and optimizing the corresponding dominant harmonics. The key of this study is to evaluate the contributions of harmonics on torque and loss, and further determines the harmonics related to them. Based on this, the torque enhancement factor and loss suppression factor are defined based on the selected dominant harmonics. And, the two factors are set as the optimization objectives, aiming at improving the characteristics of torque and loss. At the same time, to achieve an efficient optimization, a layered optimization method is presented, which includes magnet source layer and permeance layer. Based on the optimization, the motor torque is improved effectively, while the rotor iron loss is also reduced significantly. Then, a prototype motor is manufactured for experimental test. Finally, the simulation analysis and test results verify the validation of the studied motor and the proposed optimization method based on dominant harmonics.