Radial Electromagnetic Force and Vibroacoustic Mechanism Analysis of Integer Slot Permanent Magnet Synchronous Motors

This paper exhibits a detailed analysis of the radial electromagnetic force and vibroacoustic mechanism of integer slot permanent magnet synchronous motors (PMSMs). Firstly, the specific sources and spatiotemporal characteristics of radial force are analytically derived. Then, a multiphysics model considering orthotropic material parameters is established for vibration and noise calculation of an integer slot PMSM. The accuracy of the multiphysics model is verified through vibration and noise tests. Subsequently, the vibroacoustic mechanism including the dominant force and the dominant mode is revealed based on the multiphysics model. The results show that considering the stator teeth modulation effect, the vibration and noise of integer slot PMSMs mainly come from the combined effects of the 0-order and slot-order radial force. As the interaction of permanent magnet field harmonics only produces slot-order radial forces at slot frequencies, so the main peaks of vibration and noise usually appear at the slot frequencies owing to the large amplitudes of slot-order radial forces. Due to the spatial matching, the 0-mode vibration is excited by the resultant force. Besides, though there is no 2-order force, the 2-mode vibration is also aroused and amplified owing to the frequency matching, which is quite different from the traditional analysis. Finally, the 2-mode vibration is theoretically analyzed and reinforced via acceleration vibration and noise tests.