Robust position observer for sensorless direct voltage control of stand-alone ship shaft brushless doubly-fed induction generators

The aim of this paper is to investigate an adaptive sensorless direct voltage control (DVC) strategy for the stand-alone ship shaft brushless doubly-fed induction generators (BDFIGs). The proposed new rotor position observer using the space vector flux relations of BDFIG may achieve the desired voltage control of the power winding (PW) in terms of magnitude and frequency, without any speed/position sensors. The proposed algorithm does not require any additional observers for obtaining the generator speed. The proposed technique can directly achieve the desired DVC based on the estimated rotor position, which may reduce the overall system cost. The stability analysis of the proposed observer is investigated and confirmed with the concept of quadratic Lyapunov function and using the multi-model representation. In addition, the sensitivity analysis of the presented method is confirmed under different issues of parameter uncertainties. Comprehensive results from both simulation and experiments are realized with a prototype wound-rotor BDFIG, which demonstrate the capability and efficacy of the proposed sensorless DVC strategy with good transient behavior under different operating conditions. Furthermore, the analysis confirms the robustness of the proposed observer via the machine parameter changes.