Sensorless Rotor Position Detection of Doubly-Fed Induction Generators for Wind Energy Applications

This paper presents a sensorless rotor position detection method, that uses a stator flux estimation based on a parallel observer. A closed-loop rotor speed estimation from the rotor position is also proposed. The operating principles of the Doubly-Fed Induction Generators (DFIG) based on wind generation systems and the field oriented control strategy are discussed. Finally, experimental results are presented, showing transient responses for a 0.56 kW DFIG operating at unity power factor. The proposed method has excellent performance even near synchronous speed, without using any initial rotor position information.