Patent ID: 8531144

Claim:
A synchronous-machine starting device comprising: an electric power conversion unit which converts supplied electric power into AC power and supplies the AC power to an armature of a synchronous machine; an AC voltage detection unit which detects an AC voltage supplied to the armature of said synchronous machine and outputs an AC voltage signal representing said detected AC voltage; an AC current detection unit which detects an AC current supplied to the armature of said synchronous machine and outputs an AC current signal representing said detected AC current; a rotor position detection unit which detects a position of a rotor of said synchronous machine based on said AC voltage signal and said AC current signal; and an electric power conversion control unit which controls said electric power conversion unit based on the detected position of said rotor, said rotor position detection unit including: an induction voltage operating unit which calculates an induction voltage induced to the armature of said synchronous machine based on an estimated phase representing the position of said rotor, an estimated rotational speed of said rotor, said AC voltage signal, and said AC current signal, and outputs an induction voltage signal representing said calculated induction voltage; a selection unit which selects and outputs one of said induction voltage signal received from said induction voltage operating unit and said AC voltage signal received from said AC voltage detection unit; and a feedback operating unit which calculates a phase error of said estimated phase based on said induction voltage signal or said AC voltage signal received from said selection unit, calculates said estimated phase and said estimated rotational speed based on said calculated phase error, outputs a speed signal representing said calculated estimated rotational speed to said induction voltage operating unit, and outputs a position signal representing said calculated estimated phase to said electric power conversion control unit and said induction voltage operating unit.