A position-sensorless vector control of doubly-fed induction machines using adaptive reduced-order observers on holonomic reference frames

In this paper, two novel adaptive reduced-order observers are proposed for position-sensorless drives of doubly-fed induction machines. The reduced-order observers are conducted by the reduced-order models expressed on the holonomic reference frames; the stator equation on stator reference frame and the rotor equation on rotor reference frame. The proposed rotor-position estimation schemes are straightforward and simplicity for implementation without suffering from the DC drift problem arising from pure integration of stator flux. Stability analysis of the adaptive observer is carried out, and the local stability is validated by the linearization method. The design guidelines of adaptation PI gains are also introduced; the over-damped response with specified bandwidth can be successfully obtained. Simulation results of various operating conditions are provided in order to verify the proposed theoretical concepts.