Mathematical Modeling and Current-Oriented Control of Double-Inverter-Fed Wound Rotor IM Emulated as Two Virtual Cage Rotor IMs

Abstract

Stator- and rotor-side voltage source inverters (VSIs) (VSI-S and VSI-R) of a double-inverter-fed wound rotor induction machine (DI-WRIM) drive individually feed 1-p.u. power each, to extract 2-p.u. power at a 2-p.u. speed. This feature of the DI-WRIM drive is explored, in this article, to model this drive as two virtual cage rotor induction machines (CRIMs). The VSI-S connected to the stator is emulated as one VSI-fed CRIM with the rotor short circuited, while the VSI-R connected to the rotor is emulated as another VSI-fed CRIM with the stator short circuited. The mathematical modeling of the DI-WRIM drive as two virtual CRIMs, in the synchronous reference frame, is presented by considering the angle between the stator and rotor currents (γ) as a medium of coupling between the two virtual CRIMs. The proposed mathematical model of the DI-WRIM is used to demonstrate the performance of the drive in a current-oriented control (COC) technique. In the COC technique, the VSI-S is controlled in the stator current-oriented frame and the VSI-R is controlled in the rotor current-oriented frame. The proposed model and technique is tested on a 4-hp WRIM drive and the experimental results are also presented to demonstrate the satisfactory performance of the drive.