Synchronous machine starting device

1. A synchronous machine starting device comprising:

a power conversion unit for converting supplied power into AC power and supplying the AC power to an armature of a synchronous machine;

an AC voltage detection unit for detecting AC voltage supplied to the armature of said synchronous machine;

a rotor position detection unit for detecting a rotor position of said synchronous machine, based on said detected AC voltage; and

a power conversion control unit for controlling said power conversion unit, based on the detected rotor position,

said rotor position detection unit including

a level monitoring unit for outputting a first position signal indicating a timing at which a level of AC voltage supplied to the armature of said synchronous machine reaches a prescribed value, based on said detected AC voltage,

a feedback operation unit for calculating an error of an estimated phase based on said estimated phase indicating said rotor position and said detected AC voltage, calculating said estimated phase based on the calculated phase error, and outputting a second position signal indicating the calculated estimated phase, and

a selector circuit receiving said first position signal or a position signal obtained based on said first position signal, and said second position signal, selecting one of said received two position signals, and outputting the selected signal to said power conversion control portion as a signal indicating the rotor position of said synchronous machine.

2. The synchronous machine starting device according to claim 1 , wherein said rotor position detection unit further includes an AC signal generation unit outputting a third position signal that is an AC signal having a prescribed frequency, and

said selector circuit selects one of said first position signal, said second position signal, and said third position signal, and outputs the selected signal to said power conversion control unit as a signal indicating the rotor position of said synchronous machine.

3. The synchronous machine starting device according to claim 2 , wherein said rotor position detection unit further includes a switching circuit for switching whether or not to output said first position signal to said AC signal generation unit, and

said AC signal generation unit adjusts a phase of said third position signal based on said first position signal received from said switching circuit.

4. The synchronous machine starting device according to claim 3 , wherein said selector circuit selects said first position signal, and thereafter selects said third position signal after said AC signal generation unit adjusts a phase of said third position signal based on said first position signal.

5. The synchronous machine starting device according to claim 2 , wherein said rotor position detection unit further includes a switching circuit for switching whether or not to output said third position signal to said feedback operation unit, and

said feedback operation unit adjusts a phase of said second position signal based on said third position signal received from said switching circuit.

6. The synchronous machine starting device according to claim 5 , wherein said selector circuit selects said third position signal, and thereafter selects said second position signal after said feedback operation unit adjusts a phase of said second position signal based on said third position signal.

7. The synchronous machine starting device according to claim 2 , wherein said selector circuit selects said first position signal, said third position signal, and said second position signal, in this order, and outputs the selected signal to said power conversion control unit.

8. The synchronous machine starting device according to claim 2 , wherein said AC signal generation unit outputs a third position signal having a frequency corresponding to a predetermined rotational speed of the rotor during standby of said synchronous machine.

9. The synchronous machine starting device according to claim 2 , wherein said selector circuit selects said first position signal and said third position signal, in this order, based on a level of said detected AC voltage, and outputs the selected signal to said power conversion control unit.

10. The synchronous machine starting device according to claim 9 , wherein said selector circuit deselects said first position signal and selects said third position signal when a prescribed time has elapsed since a level of said detected AC voltage reaches a prescribed value or higher.

11. The synchronous machine starting device according to claim 2 , wherein said selector circuit selects said third position signal and said second position signal, in this order, based on a level of said detected AC voltage, and outputs the selected signal to said power conversion control unit.

12. The synchronous machine starting device according to claim 11 , wherein said selector circuit deselects said third position signal and selects said second position signal when a prescribed time has elapsed since a level of said detected AC voltage reaches a prescribed value or higher.

13. The synchronous machine starting device according to claim 1 , wherein

said rotor position detection unit further includes a switching circuit for switching whether or not to output said first position signal to said feedback operation unit, and

said feedback operation unit adjusts a phase of said second position signal based on said first position signal received from said switching circuit.

14. The synchronous machine starting device according to claim 13 , wherein said selector circuit selects said first position signal, and thereafter selects said second position signal after said feedback operation unit adjusts a phase of said second position signal based on said first position signal.

15. The synchronous machine starting device according to claim 1 , wherein said selector circuit selects said first position signal and said second position signal, in this order, and outputs the selected signal to said power conversion control unit.

16. The synchronous machine starting device according to claim 1 , wherein said selector circuit selects said first position signal and said second position signal, in this order, based on a level of said detected AC voltage, and outputs the selected signal to said power conversion control unit.

17. The synchronous machine starting device according to claim 16 , wherein said selector circuit deselects said first position signal and selects said second position signal when a prescribed time has elapsed since a level of said detected AC voltage reaches a prescribed value or higher.

18. The synchronous machine starting device according to claim 1 , wherein

said rotor position detection unit further includes

an AC signal generation unit for outputting a third position signal that is an AC signal having a prescribed frequency and

a switching circuit for switching whether or not to output said first position signal to said AC signal generation unit,

said AC signal generation unit adjusts a phase of said third position signal based on said first position signal received from said switching circuit, and

said selector circuit selects one of said second position signal and said third position signal and outputs the selected signal to said power conversion control unit as a signal indicating the rotor position of said synchronous machine.

19. The synchronous machine starting device according to claim 18 , wherein said selector circuit selects said third position signal and said second position signal, in this order, and outputs the selected signal to said power conversion control unit.

20. The synchronous machine starting device according to claim 19 , wherein said selector circuit selects said third position signal and said second position signal, in this order, based on a level of said detected AC voltage, and outputs the selected signal to said power conversion control unit.

21. The synchronous machine starting device according to claim 20 , wherein said selector circuit deselects said third position signal and selects said second position signal when a prescribed time has elapsed since a level of said detected AC voltage reaches a prescribed value or higher.

22. The synchronous machine starting device according to claim 18 , wherein

said rotor position detection unit further includes a switching circuit for switching whether or not to output said third position signal to said feedback operation unit, and

said feedback operation unit adjusts a phase of said second position signal based on said third position signal received from said switching circuit.

23. The synchronous machine starting device according to claim 22 , wherein said selector circuit selects said third position signal, and thereafter selects said second position signal after said feedback operation unit adjusts a phase of said second position signal based on said third position signal.

24. The synchronous machine starting device according to claim 18 , wherein said AC signal generation portion outputs said third position signal having a frequency corresponding to a predetermined rotational speed of the rotor during standby of said synchronous machine.

25. The synchronous machine starting device according to claim 1 , further comprising an AC current detection unit for detecting AC current supplied to the armature of said synchronous machine,

wherein said feedback operation unit calculates induction voltage induced at the armature of said synchronous machine based on an estimated phase indicating said rotor position, an estimated rotational speed of the rotor, and said detected AC voltage and the detected AC current, calculates an error of said estimated phase based on said calculated induction voltage, calculates said estimated phase and said estimated rotational speed based on said calculated phase error, and outputs said second position signal indicating said calculated estimated phase.