Different Rotor Segmented Approaches for Electromagnetic Vibration and Acoustic Noise Mitigation in Permanent Magnet Drive Motor: A Comparative Study

Stator slot skewing and rotor step-skewing methods are the most commonly used methods to reduce the torque ripple and electromagnetic vibration in the electric vehicle (EV) drive motor industry. However, these two methods have limitations on the suppression of the 0th-order vibration component and multiples of rotor magnetic pole number order vibration components. This article presents a novel rotor-segmented motor with different pole widths to reduce electromagnetic vibration for EVs. The principle of the presented new rotor segmented motor to mitigate the 0th-order and the multiples of rotor magnetic pole number orders vibration components are analytically analyzed and illustrated. Three multiphysics field models, i.e., conventional motor, rotor step-skewing motor, and the presented motor, were established. The electromagnetic vibration properties related performances, including air-gap flux density, radial force, torsional force, and vibration response, are extensively compared. Finally, the rotor step-skewing motor and the presented motor were prototyped, and extensive tests were conducted. The results show that the presented motor has a specific mitigating effect on electromagnetic vibration, with a significant decrease in the 0th-order vibration amplitude and the overall vibration level is the same as that of the rotor step-skewing motor.