Analysis Of Magnetic Force And Vibration Characteristics For Large Induction Motor

The vibration and noise level is an essential element in evaluating the electrical machine's quality. For high power induction machines, the electromagnetic forces and corresponding harmonic components acting on the stator are very large. Hence, the vibration and noise investigation is very important for high power induction machines. In this paper, the vibration of an induction machine with rated power of 1MW is thoroughly studied. The main work could be list as follows:Firstly, the magnetic flux density, the electromagnetic forces and corresponding harmonic components in the air gap are obtained by the combination of finite element method(FEM) analysis and analytical method(AM) analysis when the machine is running under no load and full load. The harmonic components of the magneto-motive potential and the magnetic conductance are calculated and the radial electromagnetic forces' harmonics are obtained by AM. Then, the magnetic flux density, radial forces and corresponding harmonic components in the air gap are obtained by field-circuit coupling from finite element model built by Infolytica. Compared the AM results with FEM results, the same conclusion can be obtained while there are a bit differences for the FEM mode includes the slots and teeth which have been neglected in building the AM model.Secondly, the electromagnetic forces and corresponding harmonics at different conditions such as rotor with broken bars, rotor eccentricity, the different winding connection types and rotor with open slots or close slots are found by finite element method, which lays a foundation for the further response analysis for the induction machines.Finally, the mode and harmonic analysis are carried out on a stator model taking consideration of the windings. The intrinsic frequency of the stator and the response amplitudes for different harmonics are obtained.