Model reference adaptive back-EMF estimations for sensorless control of grid-connected doubly-fed induction generators

A back-EMF model reference adaptive system (MRAS)-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 PWM 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 and will not be affected by small variations either in the rotor speed or in the output power of the DFIG.