Considerations about the modeling and simulation of air-gap eccentricity in induction motors

Abstract

This paper proposes, firstly, a precise evaluation of the inductances of induction machine (IM) by transforming the calculations into a simple calculation of surfaces. The skewing bars effect and linear rise of the magneto-motive force (MMF) across the slot in case of constant or nonuniform air-gap are taken into account. Secondly, we consider the two types of star stator winding coupling of IM, YN-connected and Y-connected. The choice of a 2-pole IM in our application is due to the fact that the majority of the previous publications have used a 4-pole IM or more. Also, and particularly, the 2-pole IM can have homopolar flux in presence of eccentricity or odd number of slots per pole. It is the reason for which it deserves a particular interest. The model is established initially in case of symmetric machine, then, in the frequent case of radial eccentricity which is the mixed eccentricity. This objective would be achieved by exploiting an extension in 2-D of the modified winding function approach (MWFA). The analysis is validated by comparing the experimental line-current spectra of the eccentric machine to the simulation results.