Because of its simple structure, high power density and high efficiency, the applications of permanent magnet synchronous machine (PMSM) gain continual expansion, and the low-noise and high-performance PMSM has also become one of the hot research spots. In [1]-[4], the analytical calculation of the air-gap magnetic field of PMSM is studied in detail, and the transient magnetic field distribution of the surface permanent magnet brushless DC machine is obtained. Accordingly, an analytical model of analyzing the radial electromagnetic force wave in fractional-slot PMSM is established, and the influence of stator slotting, etc. on electromagnetic force waves are calculated in [5]. In [6], the vibration characteristics of four different types of interior PMSMs are analyzed by the finite element method (FEM), and the influence of winding configurations on the vibration characteristics is obtained, however, it is difficult to distinguish the source of exciting wave. In this paper, a method of calculating radial electromagnetic force combining analytical method and FEM is proposed. With this method, the influence of slot size is considered, meanwhile, the integral expression of radial electromagnetic force wave is calculated accurately and conveniently. Further, the influences of slot opening width, skewed slot rate, pole arc coefficient, eccentricity on the electromagnetic force wave are analyzed, which lay the theoretical foundation for the weakening of electromagnetic vibration.
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