Theoretical and experimental analysis of electric vehicle motor dynamics under the coupling of harmonic current and temperature excitation

Abstract

The NVH performance of electric vehicles is crucial for human comfort, and the electric drive system is key to NVH performance. Permanent magnet synchronous motors experience high-temperature increases under high-speed operating conditions, resulting in motor structure deformation at high-temperatures. The radial deformation of the stator alters the airgap dimensions of the motor’s electromagnetic field. The airgap of the motor’s magnetic field has high-sensitivity to these changes aggravating the vibration and noise problems. Harmonic currents in high-speed vehicle motors add to these problems. Therefore, motor dynamics must be studied under the joint influences of airgap distortion and harmonic currents. We proposed a method of modeling permanent magnet synchronous motors under the joint effect of harmonic currents and temperature fields. And established an accurate multi-field coupled vibration response prediction model for permanent magnet synchronous motors. The accuracy of the vibration prediction model was subjected to a bench test. The vibration characteristics of the motor were studied using order and spectrum analyses. We found that the airgap magnetic-field distortion, due to the motor and stator thermal deformation, significantly affected the motor vibration characteristics. The main motor vibration noise was caused by the 24th and 48th order electromagnetic force waves. This provides a reference for establishing an accurate vibration prediction model for permanent magnet synchronous motors.