A stator-equation-based reduced-order observer for position-sensorless vector control system of doubly-fed induction machines

In this paper, a novel adaptive reduced-order observer is proposed for the position-sensorless drive of doubly-fed induction machines. The reduced-order observer is conducted by the reduced-order model expressed on the holonomic reference frame; the stator equation on stator reference frame. The proposed rotor-position estimation scheme is straightforward and simplicity for implementation without suffering from the DC drift problem arising from pure integration of stator flux. The proposed rotor-position estimation is integrated with the stator-flux vector control. Experimental results of various operating conditions are provided in order to verify the proposed theoretical concepts. The proposed sensorless system can successfully operate in both motor and generator regions, and the performances of sub-synchronous, synchronous and super-synchronous modes are also evaluated.