Analysis Of Rotor Eccentricity Fault And Vibration For Switched Reluctance Motors

The switched reluctance motor(SRM) as a new type of variable speed motor,which has the advantages of simple and rugged structure, excellent driving performance and high reliability, has been widely concerned. However, the problems of remarkable vibration and noise restrict its development and application in the relevant fields in a great extent. The study shows that the noise of SRM is derived from the vibration and deformation of the stator resulting from the pulsating radial magnetic pull. For the problems of vibration and noise, many effective methods have been put forward in the aspects of motor design and control by researchers. However, due to the low precision machining and installation and other reasons, it is bound to the presence of eccentricity,which results in the uneven air gap between the stator and rotor. Since the air-gap permeance is much less than the permeability of core material. Therefore, the uneven air-gap will lead a great change in the air-gap magnetic flux density, and then, the larger unbalance magnetic pull will produced, which will deteriorate the vibration and noise of SRM. Therefore, the analyses of eccentricity faults and the influences of eccentricity fault on SRM are the important aspects for the diagnosis and the optimization design of SRM.In the paper, aiming at the static and dynamic eccentricity faults of SRM, the influences of eccentricity faults on the air-gap length, flux linkage and torque were derived theoretically, considering the eccentric direction and ratio. The two-dimensional finite element model of SRM for static magnetic analysis was established, and the influences of eccentric direction and ratio on the flux linkage and torque were verified by the FEM. According to the simulation results, the flux-linkage can be regarded as an index for the diagnosis of eccentricity fault of SRM.The field-circuit coupled transient finite element models of SRM with different eccentricities were established. The electromagnetic forces were calculated by the virtual displacement method and the Maxwell stress method respectively. The spectral analyses of air-gap flux density, electromagnetic force and the electromagnetic force density in SRM were conducted by the fast Fourier transform(FFT), and the influences of eccentricity faults on the electromagnetic force and other parameters are obtained.Finally, the modal analyses of stator structure and stator and shell structure wereconducted by the finite element software Ansys, and the natural frequency and vibration modes are obtained. The electromagnetic-structural weak coupling model was established by the connection of electromagnetic analysis and harmonic response analysis. The analyses of the vibration displacement and vibration acceleration under different eccentricities were conducted by the modal superposition method, and the effects of eccentricity faults on the vibration characteristic are obtained. The simulation results have the important theoretical values for the optimization design and the eccentricity fault diagnosis of SRM.