Unbalanced Magnetic Pull Analysis for Rotordynamics of Induction Motors

This study investigates the characteristics of unbalanced magnetic pull (UMP) and its effect on the rotordynamics of induction motors. The UMP calculation method utilizes a simple analytical UMP model. To improve the accuracy of the result, the magnetizing currents and correction factor functions are calculated at different slip and air-gap eccentricity values using Finite Element Analysis (FEA). The obtained results are incorporated into the analytical UMP equation. Utilizing this method, the variation of UMP force and stiffness due to the change in slip, eccentricity, supply frequency and the relative location of the shortest air gap with magnetic flux by one pole of the stator is investigated in case of 30 kW induction motor. In addition, the dynamic behavior of the motor is simulated and the effect of UMP in rotordynamics is defined.