Experimental behaviour of unbalanced magnetic pull in 3-phase induction motors with eccentric rotors and the relationship with tooth saturation

This paper explains, in simple terms, the influences affecting the magnitude of the unbalanced magnetic pull (UMP) generated in an induction motor where the rotor is not centred. It explains the phenomena in terms of harmonic field theory and reviews the experimental data currently published and puts forward further results in order to explain the reduction in UMP due to localised iron saturation where the flux is concentrated. Trends and relationships are drawn from the evidence so that UMP can be assessed in other machines using simple analytical techniques.