Research On The Vibration Of AC Motor Caused By Faults Based On Field-circuit Coupling Method

The vibration and noise of electrical machine is the important symbol for evaluating the electrical machinery quality. The bigger vibration in the condition of motor fault can inflect the other electrical machinery quality and its use life, so it is very important to research the vibration of the AC motor. The electrical machine vibration and noise research is extremely complex, it involves the electromagnetic analysis, the energy conversion, the mechanical vibrations, the physical acoustics, electronics and mathematics and so many disciplines. The research centered on the vibration question of the Y2-90S-4 asynchronous machines. From the unbalanced electromagnetic force, the vibration excitation and structure vibration characteristic of asynchronous machines are analyzed and confirmed through the experiment.Firstly, the basic concept, the advantages and disadvantages for the general steps of the finite element method are introduced; the basic principle and solving steps on the field coupled time-step finite element method are introduced detailedly, it provided a theoretical basis to solve the follow-up electromagnetic field questions in the motor.Then, the finite element analysis software ANSYS used as a tool, the electromagnetic field parameters of the motor were calculated through the field-circuit coupling method. The simulation model of experimental motor Y2-90S-4 was built, the distribution of magnetic field lines, magnetic flux density and the electromagnetic force of normal motor was calculated.Through changing the parameter of the rotor, the one and two broken-bar fault was simulated, the various parameters of the above circumstances were analysed, with a view to find fault characteristics and laws provide a basis for the electrical fault diagnosis. On the basis, the characteristics of the induction motor structural vibration were studied. The finite element modal analysis was done in ANSYS environment, the natural frequency of induction motor modal study and calculated by using Block Lanczos method to extract all modes. In accordance with the true size and shape of Y2-90S-4 model three phase induction motors, the 3D simulation model of the electrical experiments motor in Solidworks environment, provided a basis for avoiding the resonance frequency.Finally, the electromagnetic vibration character which caused by imbalance magnetic pull of the motor in defferent faults was introduced, experimental analysis of the real motor was done and the motor in the normal operation of the no-load and load was tested; the vibration characteristic of the motor in fault condition was monitored by creating broken-bar faults artificially. Through comparing theoretical analysis, simulation calculation and the experimental results, 'the vibration characteristic of the motor was found to create more condition for fault diagnosis of the motor.