EFFECT OF SATURATION 3RD HARMONIC ON THE PERFORMANCE OF SQUIRREL-CAGE INDUCTION MACHINES

This paper contributes to the understanding of the behavior of the saturation third harmonic and how energy is converted from fundamental to third harmonic form in a squirrel-cage induction machine in the presence of magnetic saturation. It is shown that the power transferred via the third harmonic airgap flux is accounted for by a change in the magnitude and phase-shift in the fundamental airgap flux. A procedure is proposed to link the rotor third harmonic circuit quantities to a set of equivalent fundamental component circuit quantities which leads to a modified equivalent circuit for the induction machine.