Influence of Sine-Type Rotor Design on Electromagnetic Vibration Characteristics of Surface-Mounted Permanent Magnet Synchronous Machines

The sinusoidal rotor field design alters the harmonic distribution of electromagnetic force waves in surface-mounted PMSMs, exerting a complex influence on electromagnetic vibration. First, the analytical expressions for electromagnetic force waves are derived theoretically, revealing the harmonic coupling mechanism and their phase relationships. Second, finite element models of both tile-shaped and sine type permanent magnet motors are established, and a comparative analysis is performed on the harmonic characteristics of the no-load back EMF and the frequency spectrum of electromagnetic force waves. Subsequently, a vibration calculation model is constructed to clarify the differential effects of the sine type design on the 0th-mode vibration and the minimum non-zero mode vibration. The study shows that the sine type design makes the electromagnetic force waves more sinusoidal, but it increases the amplitude of the second temporal harmonic of the electromagnetic force, significantly amplifies the minimum non-zero mode vibration, and makes it the dominant component of the overall motor vibration. Finally, the correctness of the theoretical analysis and simulation results is verified through experiments on four prototypes.