Source identification and hierarchical suppression of measured carrier frequency noise in variable frequency drive system

Abstract Vibration and noise signals have long been crucial for predicting motor performance and detecting faults. In high-performance variable-frequency permanent magnet synchronous motor (PMSM) drive systems, electromagnetic (EM) vibrations and noise arising from high-frequency current harmonics, especially around the carrier frequency, significantly adversely impact motor performance and the surrounding application environment. Furthermore, these disturbances can interfere with the operation of nearby precision electronic devices, resulting in measurement signal distortion. To address this issue, this paper presents a comprehensive analysis of carrier frequency radial EM force density (CFREMFD), which is the source of measured carrier frequency noise in PMSM. A detailed analytical model of CFREMFD is established, considering both carrier frequency current harmonics and saliency effects. The spatial-temporal characteristics of CFREMFD of a 10-pole 12-slot interior PMSM coupled with control system are investigated and predicted through the analytical model and multiple finite element analysis (FEA), revealing the dominant contributions from excitation magnetic field, fundamental and carrier frequency armature field interactions, with saliency effects superposing flux harmonic and introducing new components. Furthermore, a novel optimization framework that combines carrier frequency shifting FEA with hierarchical optimization is proposed to minimize CFREMFD by adjusting rotor dimensions and topology. Experimental validation demonstrates that the optimized design effectively suppresses high-frequency vibration and the measured carrier frequency noise is reduced 5.62 dBA from 27.79 dBA. Through comprehensive analysis and experimentation, it has been demonstrated that vibrations and noise near the carrier frequency are induced by CFREMFD, facilitating the prediction of trends in substantial high-frequency variations and amplitude fluctuations of vibration and noise signals. This research provides theoretical support and practical strategies for the rapid optimization of carrier frequency EM noise in variable frequency drive system, showcasing innovative methods to mitigate the negative impacts of carrier frequency current harmonics during motor design.