Dual mode rectifier, system and method

• US 20050286279A1
• Filed: 06/23/2004
• Published: 12/29/2005
• Est. Priority Date: 06/23/2004
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Datta, Rajib, Chen, Kunlun
• Granted Patent: US 7,203,078 B2
• Time in Patent Office: Days
• US Class Current: 363/89
• CPC Class Codes: H02M 7/219 in a bridge configuration
• CPC Class Codes: H02P 2101/15 for wind-driven turbines
• CPC Class Codes: H02P 9/48 Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle H02P9/04 - H02P9/46 take precedence

Abstract

A system for generating an output power to a load is provided. The system comprises a generator configured for generating a variable frequency output power and a dual mode rectifier coupled to the generator and configured for being switched between a passive mode and an active mode. The dual mode rectifier comprises a passive rectifier coupled to output terminals of the generator and configured for operating in the passive mode and an active converter coupled to tappings from windings of the generator and configured for operating in the active mode.

Claims

1. A system for generating an output power to a load, the system comprising:

a generator configured for generating a variable frequency output power; and

a dual mode rectifier coupled to the generator and configured for being switched between a passive mode and an active mode, wherein the dual mode rectifier comprises;

a passive rectifier coupled to output terminals of the generator and configured for operating in the passive mode; and

an active converter coupled to tappings from windings of the generator and configured for operating in the active mode.

2. The system of claim 1, further comprising control circuitry configured for causing the active converter to provide active power when the generator is operating at or below a first speed.

3. The system of claim 2, wherein the control circuitry is further configured for causing the passive rectifier to provide power when the generator is operating at or above a second speed.

4. The system of claim 3, wherein the first speed is equal to the second speed.

5. The system of claim 3, wherein the second speed is higher than the first speed.

6. The system of claim 3, wherein the first speed ranges from about 0.75 per unit to 0.8 per unit.

7. The system of claim 3, wherein the second speed ranges from about 0.8 per unit to 0.85 per unit.

8. The system of claim 3, wherein the control circuitry is further configured for causing the active converter to induce a reactive current in the generator when the generator is operating at or above the second speed.

9. The system of claim 8, wherein the control circuitry is further configured to use the reactive current for regulating an output voltage of the generator.

10. The system of claim 1, wherein the active converter is further configured to induce harmonic currents to cancel harmonic currents introduced by the passive rectifier in the generator winding.

11. The system of claim 1, further comprising a turbine coupled to the generator.

12. The system of claim 11, wherein the turbine comprises a wind turbine.

15. The dual mode rectifier of claim 12, wherein the passive rectifier is configured to provide power to the load when the generator is operating at or above a second speed.

18. The system of claim 12, wherein the active converter is further configured to inject harmonic currents to cancel harmonic currents introduced by the passive rectifier in the generator winding.

19. The dual mode rectifier of claim 12, wherein the passive rectifier comprises diodes.

20. The dual mode rectifier of claim 12, wherein the active converter comprises active switches.

13. A dual mode rectifier configured for being switched between a passive mode and an active mode, the dual mode rectifier comprising:

a passive rectifier coupled to output terminals of a generator and configured for operating in the passive mode; and

an active converter coupled to tappings from windings of the generator and configured for operating in the active mode,

wherein the dual mode rectifier is configured for providing power to a load.

14. The dual mode rectifier of claim 13, wherein the active converter is configured to provide active power to the load when the generator is operating at or below a first speed.

16. The system of claim 14, wherein a control circuitry coupled to the dual mode rectifier is configured for causing the active converter to induce a reactive current in the generator when the generator is operating at or above the second speed.

17. The system of claim 16, wherein the reactive current can be used to regulate an output voltage of the generator.

21. A method for generating an output power to a load, the method comprising:

generating a variable frequency output power; and

rectifying the variable frequency output power to output power;

wherein the rectifying comprises

operating in an active mode when the output power is below a first threshold value, and

operating in a passive mode when the output power is above a second threshold value.

22. The method of claim 21, wherein rectifying further comprises controlling a passive rectifier to operate when the output power is above the second threshold value and an active converter to operate when the output power is below the first threshold value.

23. The method of claim 21, wherein the first threshold value is equal to the second threshold value.

24. The method of claim 21, wherein the second threshold value is greater than the first threshold value.

25. The method of claim 21, wherein the first threshold value is 0.4 to 0.5 per unit.

26. The method of claim 21, wherein the second threshold value is 0.5 to 0.6 per unit.

27. The method of claim 21, further comprising inducing a reactive current in a generator when the output power is above the second threshold value.

28. The method of claim 21, further comprising minimizing harmonic currents in the generator.

29. The method of claim 28, further comprising regulating an output voltage of the generator using the reactive current.

30. A system for generating an output power to a load, the system comprising:

a generator configured for generating a variable frequency output power;

a wind turbine coupled to the generator;

a dual mode rectifier coupled to the generator and configured for being switched between a passive mode and an active mode, wherein the dual mode rectifier comprises;

a passive rectifier coupled to output terminals of the generator and configured for operating in the passive mode;

an active converter coupled to tappings from windings of the generator and configured for operating in the active mode; and

control circuitry configured for causing the active converter to provide active power when the generator is operating at or below a first speed and for causing the passive rectifier to provide power when the generator is operating at or above a second speed.

31. The system of claim 30, wherein the first speed is equal to the second speed.

32. The system of claim 30, wherein the second speed is higher than the first speed.

33. The system of claim 30, wherein the control circuitry is further configured for causing the active converter to induce a reactive current in the generator when the generator is operating at or above the second speed.

34. The system of claim 30, wherein the control circuitry is further configured to use the reactive current for regulating an output voltage of the generator.