Sensor-less hysteretic vector control of doubly-fed machine for wind power generators

As one of the advanced technologies, the variable speed constant frequency doubly-fed induction generation has been widely used nowadays and the usual vector control algorithms are mostly based on voltage sinusoidal pulse width modulation technology. In this paper the current hysteresis pulse width modulation technology is introduced to simplify the control system. An open-loop speed observer is designed according to the hysteresis vector control system. By using the rotor current reference components instead of the real current components, the observer design is simplified and observing effect is evidently improved. The dynamic respond performance becomes better in hysteresis vector control system, and the whole control process gets independent on any electric machine parameters. The proposed speed observer overcomes some of the disadvantages of the traditional open-loop speed observers. PSCAD/EMTDC simulation software is employed to test the proposed scheme, and the results demonstrate the efficiency of the control scheme as well as the speed observer.