Calculation and measurement of unbalanced magnetic pull in cage induction motors with eccentric rotors. I. Analytical model

The paper describes an analytical model for cage induction motors with a static eccentric rotor. The method is based on an airgap permeance approach including stator and rotor MMF harmonics. The stator windings are resolved into harmonic conductor density distributions that allow different seriedparallel winding connections to be accommodated in a straightforward manner. Sinusoidal and homopolar airgap field components are identified and the total airgap field distribution is used to determine the radial forces on the rotor. The model examines the principal harmonic interactions that influence the unbalanced magnetic pull.