Control scheme for source voltage sensorless PWM converters under source voltage unbalance

This paper presents a control scheme for three-phase PWM converters which have no ac-side voltage sensors. In spite of no source voltage sensors, the proposed method estimates exact grid angle and voltages, which are the essential parts for the power transfer between DC link of PWM converter and AC source. The method works not only in normal balanced AC source case but also in faulty unbalanced cases. The validity of proposed method has been evaluated by computer simulation and experimental result with 10kW PWM Voltage source converter.