Dynamic Eccentricity Impact on Electromagnetic Vibration and Acoustic Noise of Interior Permanent Magnet Synchronous Motors With Different Numbers of Parallel Branches

Eccentric faults always occur in permanent magnet (PM) motors due to installation errors and irregular wear, which lead to abnormal electromagnetic vibration, unbalanced magnetic force (UMF), and acoustic noise. This article aims to investigate the impact of dynamic eccentricity (DE) on the electromagnetic vibration of interior PM synchronous motors (IPMSMs) considering different numbers of parallel branches. The universal analytical expression of electromagnetic excitation force for IPMSMs with DE applicable to different pole-slot combinations is derived, and the spatial-temporal characteristics of radial electromagnetic force (REF) for IPMSMs with DE are investigated. Afterward, a method to mitigate the vibration and noise caused by DE fault by optimizing the number of parallel branches is proposed. The co-simulation model is built based on the investigated motor to compare the branch currents, airgap magnetic flux, radial force density, and UMF. Finally, intensive vibration and acoustic noise experiments are implemented based on a 10-kW 8-pole/36-slot IPMSM with DE. The simulation and experiment results verify that DE introduces electromagnetic force harmonic component (1, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}_{\mathrm {m}}$ </tex-math></inline-formula>), and the balanced current in the parallel branches can mitigate the electromagnetic vibration and UMF at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{\mathrm {m}}$ </tex-math></inline-formula>.