New approach for the modeling of induction machines operating under unbalanced power system

Abstract

Summary In this paper, a new analytical method for the modeling of the star connected induction motors operating under unbalanced power supply is developed using coupled circuits theory. This method takes into account the increase of the common point voltage during unbalanced supply conditions. The equations, which describe the state model as well as the calculation of machine inductances, are presented. The calculation of inductances is based on the magnetomotive force distribution through the machine air-gap. The advantages of the proposed method are multiple. The space and time harmonics can be taken into account. It can also be extended for the analysis of faulty induction machines. Magnetic saturation, skin effect, skewed rotor, and slotting effects can be integrated in the calculation of the machine inductances by introducing some techniques to the basic coupled circuit theory. This method reduces strongly the time simulation because of the simple numerical representation of the inductances and their derivatives. The obtained results show good agreement with other results, which have been obtained using finite elements method and symmetrical components approach. The particularity of this work is that it takes in consideration the increase of the common point voltage during unbalanced supply conditions. Simulation results show the consistency and the applicability of the proposed method for the modeling of induction motors operating under unbalanced power system. Copyright © 2016 John Wiley & Sons, Ltd.