Considerations about Rotor Current of an Asymmetrically Supplied Induction Machine

Abstract

If an induction machine is powered by an asymmetric three-phase voltage system, asymmetric three-phase quantities of interest (voltages, currents, fluxes) result. The rotating magnetic field is no longer circular but elliptical. In addition the hodograph of all quantities have become elliptical. The dissymmetry factor of the rotor current depends on the dissymmetry factor of the supply voltage and also on the operating conditions. In practical applications there is a strong influence of both operating conditions and rotor speed on the asymmetric regime of the rotor quantities. The goal of this paper is to study to what extent the asymmetry of the rotor quantities depends on the operating conditions. This matter is studied by theoretical evaluation, confirmed and completed by simulation results.