Model Reference Adaptive Back-Electromotive-Force Estimators for Sensorless Control of Grid-Connected DFIGs

A back-electromotive force (EMF) model reference adaptive system based sensorless control scheme is proposed for a grid-connected doubly fed induction generator (DFIG). Based on the stator-side and the rotor-side dynamic models of the DFIG, both the reference model and the adaptive model of the proposed back-EMF based DFIG are investigated. The adaptation mechanism of the proposed controller and the stability of the closed-loop system are derived by Popov's criterion. Real-time simulation studies are performed with detailed dynamics including pulse-width modulation synthesis. A 2.2 kW DFIG experimental platform is constructed to validate the proposed method by hardware experiments. Both results indicate that proper speed estimations can be achieved by the proposed method. Experimental results indicate that the proposed method can provide good robustness against rotor speed variations or output power variations.