Three-phase induction motor dynamic mathematical model considering air-gap irregularities

The non-inclusion of the air-gap irregularities in the three-phase induction machine dynamic model causes the elimination of the electromagnetic torque oscillation around a mean value. Usually this phenomenon is due to the rotor eccentricity. In this paper it supposes that the rotor presents elliptical or egg-shaped form as it really happens. In this regard, it is proposed an analytical formulation of the phenomenon and this formulation is extended also to the analysis of non-circularities in the stator surface. Experimental results are compared with simulated ones. From those results it was verified that the developed model can reproduce with good accuracy the oscillation of the electromagnetic torque.