Influence of rotor magnetic circuit structure on electromagnetic vibration and noise of a permanent magnet synchronous motor

Load-driving equipment such as underground coal mine fans and water pumps operates continuously for long periods in humid, dusty, space-constrained environments where maintenance is inconvenient, and needs to meet operating requirements such as frequent starting and stopping and regulation under complex working conditions. As a result, electromagnetic excitation generated by the driving motor induces structural vibration and noise, affecting the operational reliability and safety of the equipment. To address this problem, a mining Permanent Magnet Synchronous Motor (PMSM) was taken as the research object. Under the condition that the stator structural parameters, the permanent magnets usage, and the winding configuration were kept consistent, four typical rotor magnetic circuit structure models, namely surface-mounted, I-shaped, spoke-type, and V-shaped structures, were established. Based on an electromagnetic-structural-acoustic multiphysics coupled finite element method, the electromagnetic force, stator vibration response, and sound power level distribution characteristics of PMSM for different rotor magnetic circuit structures under no-load and load conditions were studied. Through modal analysis, the influence mechanism of the stator core modes and stator–housing assembly modes on vibration and noise characteristics was revealed. The results showed that different rotor magnetic circuit structures significantly changed the air-gap magnetic field distribution and radial electromagnetic force characteristics of the PMSM, thereby affecting stator vibration and the overall noise level of the motor. The spoke-type structure showed better vibration suppression and noise control capability over the full speed range. Its corresponding stator vibration response and sound power level were generally lower, indicating a good advantage for low-noise operation. The modal analysis results showed that the stator–housing assembly modes significantly improved the structural dynamic characteristics of the PMSM, markedly increased the 2nd to 5th natural frequencies, and increased the separation between these frequencies and the main electromagnetic excitation frequencies, thereby effectively reducing the resonance risk and improving the vibration and noise performance of the PMSM. Based on the spoke-type structure, multi-objective optimization design of the PMSM was carried out. Under the premise that the permanent magnets usage remained unchanged, key structural parameters were jointly optimized. After optimization, the average output torque of the PMSM increased from 70.7 N·m to 71.5 N·m, and the main radial electromagnetic force components all decreased. Among them, the 16th-order double-frequency component decreased from 48.66 N to 46.90 N, and the 14th-order quadruple-frequency component decreased from 11.23 N to 10.70 N, indicating that the vibration and noise characteristics of the PMSM were further improved while the electromagnetic performance was taken into account.