Sources and Characteristics of Unbalanced Magnetic Pull in Three-Phase Cage Induction Motors With Axial-Varying Rotor Eccentricity

This paper puts forward a model for assessing unbalanced magnetic pull (UMP) due to rotor eccentricity in cage induction motors that takes into account the axial variation in the eccentricity. It is tested using ten- and four-pole machines with experimental results validating the model. This paper assesses the effects of rotor differential flux, saturation, bar number, and variable-frequency operation on the UMP and highlights the key points for the generation of UMP in cage induction motors. Both dynamic and static eccentricities are studied.