| Bearingless switched reluctance motor (BSRM) integrates the traditional magnetic pearing and general switched reluctance motor(SRM), possesses both functions of rotation and suspension. At the same time, it combines magnetic bearing’s advantages of no friction, no contact, long life and switched reluctance motor’s advantages of simple structure, high speed, good performance.and so on. Therefore, the bearingless switched reluctance motor has a broad application prospect in many fields, such as high speed machine tool, a flywheel energy storage, aerospace and other fields. But the Bearingless switched reluctance motor as a special kind of switched reluctance motor is also faced with the same problem of electromagnetic vibration and noise.This paper carries on the analysis emphatically from the aspects:the eccentric rotor geometry features, the stator modal, eccentric radial force, mathematical modeling, vibration based on the BSRM with12/8poles as the research object.First, previous studies have pointed out that the vibration in switched reluctance motor is mainly caused by the rotor’s deviation from the geometric center,which leads to the unilateral magnetic force on the stator[63]. The deformation of motor’s stator would happen to cause the vibration noise, if the unilateral magnetic force acts on the stator for a long time, so the rotor eccentricity can not be ignored. Therefore, the mathematical model of radial force is deduced in this paper with the consideration of the rotor’s eccentric displacement, and the accuracy of the model is validated by finite element analysis, making up the defects of the existing mathematical model.Secondly, the deformation of the stator caused by the unbalanced magnetic force will further results in uneven air gap, leading to greater vibration and noise, therefore research on the relationship between the deformation of the stator and radial force is very important. The stator’s deformation changing with the magnitude of different static forces is analyzed and compared in this article; the degree of stator’s deformation changing with the different stator yoke thickness under the effect of the same force is compared; the deformation’s maximum and minimum value for four different kinds of the stator’s pole tooth under the same effect of static force is compared. When the natural frequency of the stator is the same as the harmonic frequency of radial force, the vibration and noise is particularly obvious, therefore the stator modal analysis of BSRM with12/8poles is carried on in this article, and the vibration frequency and the corresponding vibration model are got, which lay the foundation for the later study of rotor eccentricity.Again, to find harmonic frequency of the radial force acting on stator consistent with the natural frequency of the stator, both models of a12/8pole BSRM and a12/8pole SRM wtih different rotor’s eccentricity are established in this paper. The electromagnetic field and the radial force acted on the stators of the two kinds of motors with different rotor’s eccentricity are analyzed and compared; Then every order harmonic amplitude of the radial force is comparied by the Fourier analysis.Then, a sharing suspension winding connection way of Bearingless switched reluctance motor with12/8poles is proposed in this paper, the radial force acting on stator and electromagnetic torque in the sharing suspension winding connection mode and the traditional winding connecting mode are compared by the finite element analysis. This paper demonstrates that torque ripple and radial force ripple in the proposed winding connection mode is smaller than that in the traditional suspension winding connection mode, so that the vibration noise of BSRM can be reduced.Finally, the dynamic simulation control system of BSRM with12/8poles based on the deduced mathematical model of radial suspension force considering rotor eccentricity is built in MATLAB, and the radial suspension is basically realized. |
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