Mathematical and Natural Modeling of Oscillations in Induction Motors with Static Rotor Eccentricity

Source abstract

The article discusses the issues of improving the quality of diagnostics of induction motors in the presence of static rotor eccentricity (uneven air gap). In the process of assembly and repair of an induction electric drive, violations of the manufacturing and assembly technology may occur, in particular, the displacement of the rotor axis relative to the stator axis. This defect can also occur when the rotor bearings are worn. When operating and repairing asynchronous electric motors according to the actual state, reliable diagnostic information plays an important role, in particular, on vibration parameters. In order to prevent emergency situations with the decommissioning of the electric motor, it is necessary to fully study the power vibration characteristics for this defect. Theoretical and experimental studies of mechanical oscillations of an induction motors arising from the violation of the symmetry of the annular gap between the stator and the rotor have been carried out. In this work, a mathematical model of the formation of radial forces in the air gap of the electric motor is built, according to which calculations are made for the induction motors model AИP63B4. An assessment is given of the change in the amplitude and harmonic composition of the radial forces at various values of the static eccentricity of the rotor. The conducted full-scale simulation confirmed the results of theoretical studies of the influence of the level of defect development on the harmonic composition of mechanical vibrations during engine operation under load and in idle mode. In particular, the characteristic spectral components of radial vibration on the motor supports are determined. Sufficient vibration diagnostic features have been identified that allow determining the presence of this defect and the degree of its danger. The good convergence of the theoretical and experimental results of the studies makes it possible to determine the change in diagnostic signs in the entire possible range of defect development. The vibrational signs of this type of defect, described in various literature sources, were refined.