Uninterruptible power supply systems and methods using rectified AC with current control

• US 6,753,622 B2
• Filed: 03/02/2001
• Issued: 06/22/2004
• Est. Priority Date: 03/02/2001
• Status: Expired due to Term

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Powerware Corporation (Eaton Corporation PLC.)
• Inventors: Oughton, George W. Jr.
• Primary Examiner(s): Toatley, Jr., Gregory J.
• Application Number:
  US09/798,409
• Publication Number:
  US 20020122322A1
• Time in Patent Office: 1,208 Days
• Field of Search: 307/64, 307/66, 307/125, 307/128, 307/130, 307/131, 363/65, 363/67, 363/69, 363/70
• US Class Current: 307/64
• CPC Class Codes: H02J 9/061 for DC powered loads
• CPC Class Codes: H02M 1/10 Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from ac or dc

Abstract

An uninterruptible power supply (UPS) system includes an AC input port, a DC input port, and an output port configured to be connected to an AC load. A rectifier circuit is coupled to the AC input port, and a power transfer control circuit is coupled to the rectifier circuit output, the DC input port and the output port. The power transfer control circuit produces a DC voltage at the AC load from a rectified voltage produced by the rectifier circuit in a first mode of operation and from a DC voltage at the DC input port in a second mode of operation. A current control circuit, e.g., a boost regulator, may control a current from at least one of the rectifier circuit and the DC input port responsive to a control input. A DC/DC converter circuit may be coupled between the DC input port and the output port.

Claims

1. An uninterruptible power supply (UPS) system, comprising:

an AC input port configured to be connected to an AC power source;

a DC input port configured to be connected to a DC power source;

an output port configured to be directly connected to an AC load;

a rectifier circuit coupled to the AC input port; and

a power transfer control circuit coupled to the rectifier circuit, the DC input port and the output port, the power transfer control circuit operative to produce a DC voltage at the output port from a rectified voltage produced by the rectifier circuit in a first mode of operation and to produce a DC voltage at the output port from a DC voltage at the DC input port in a second mode of operation, the power transfer control circuit including;

a current control circuit configured to be coupled between the output port and at least one of the rectifier circuit and the DC input port and operative to control a current from the at least one of the rectifier circuit and the DC input port responsive to a control input; and

a switching circuit operative to couple and decouple the DC input port to and from the output port.

2. A UPS system according to claim 1, wherein the current control circuit is operative to control a current at the AC input port responsive to the control input.

3. A UPS according to claim 2, wherein the current control circuit is operative to control at least one of a power factor and a harmonic current at the AC input port responsive to the control input.

4. A UPS system according to claim 3, wherein the current control circuit comprises a boost regulator circuit.

5. A UPS system according to claim 1, wherein the current control circuit is further operative to regulate a voltage at the output port responsive to the control input.

6. A UPS system according to claim 1, wherein the switching circuit is operative to decouple the DC input port from the current control circuit in the first mode of operation and to couple the DC input port to the current control circuit in the second mode of operation.

7. A UPS according to claim 6, wherein the current control circuit is operative to generate a boosted DC voltage at the output port from a DC voltage at the DC input port in the second mode of operation.

8. A UPS system according to claim 1, wherein the power transfer control circuit further comprises a DC/DC converter circuit coupled between the DC input port and the output port.

9. A UPS system according to claim 8, wherein the DC/DC converter circuit is operative to generate a boosted DC voltage at the output port from a DC voltage at the DC input port in the second mode of operation.

10. A UPS system according to claim 8, wherein the DC/DC converter circuit provides galvanic isolation between the DC input port and the output port in the second mode of operation.

11. A UPS system according to claim 8, wherein the DC/DC converter circuit comprises an open-loop converter.

12. A UPS system according to claim 8, wherein the DC/DC converter circuit comprises a forward converter.

13. A UPS system according to claim 1, further comprising a DC power source connected to the DC input port.

14. A UPS system according to claim 1 in combination with an AC load coupled to the output port.

15. A UPS system according to claim 1, wherein the control input comprises at least one of a voltage at the AC input port, a current at the AC input port, a voltage at the DC input port, and a voltage at the output port.

16. An uninterruptible power supply (UPS) system, comprising:

an AC input port configured to be connected to an AC power source;

a DC input port configured to be connected to a DC power source;

an output port configured to be directly connected to an AC load;

a rectifier circuit coupled to the AC input port;

a switching circuit operative to couple the DC input port to the output port responsive to a first control input to apply a DC voltage to the AC load; and

a power factor correction circuit configured to connect the rectifier circuit to the output port to apply a DC voltage to the AC load and operative to control a power factor at the AC input port responsive to a second control input.

17. A UPS system according to claim 16, wherein the switching circuit is operative to decouple the DC input port from the output port responsive to an AC voltage at the AC input port meeting a first predetermined criterion and wherein the switching circuit is operative to couple the DC input port to the output port when the AC voltage at the AC input port meets a second predetermined criterion.

18. A UPS system according to claim 16, wherein the switching circuit is operative to couple the DC input port to the output port via the power factor correction circuit.

19. A UPS system according to claim 18, wherein the power factor correction circuit is operative to generate a boosted DC voltage at the output port from a DC voltage at the DC input port.

20. A UPS system according to claim 16, further comprising a DC/DC converter circuit coupled between the DC input port and the switching circuit.

21. A UPS system according to claim 16, wherein the control input comprises at least one of a voltage at the AC input port, a current at the AC input port, a voltage at the DC input port, and a voltage at the output port.

22. An uninterruptible power supply (UPS) system, comprising:

an AC input port configured to be connected to an AC power source;

a DC input port configured to be connected to a DC power source;

an output port configured to be directly connected to an AC load;

a rectifier circuit having an input coupled to the AC input port and an output coupled to the output port;

a power transfer control circuit coupled to the rectifier circuit output, the DC input port and the output port, the power transfer control circuit operative to produce a DC voltage at the output port from a rectified voltage produced by the rectifier circuit in a first mode of operation and to produce a DC voltage at the output port from a DC voltage at the DC input port in a second mode of operation, the power transfer control circuit including a DC/DC converter circuit configured to be coupled between the DC input port and the output port.

23. A UPS system according to claim 22, wherein the power transfer control circuit comprises a switching circuit coupled to the DC/DC converter circuit and the output port, the switching circuit operative to couple and decouple the DC/DC converter circuit to and from the output port responsive to an AC voltage at the AC input port.

24. A UPS system according to claim 22, wherein the DC/DC converter circuit is operative to generate a boosted DC voltage from a DC voltage at the DC input port.

25. A UPS system according to claim 22, wherein the DC/DC converter circuit is operative to provide galvanic isolation between the DC input port and the output port while transferring power between the DC input port and the output port.

26. A UPS system according to claim 22, wherein the DC/DC converter circuit comprises an open-loop converter.

27. A UPS system according to claim 22, wherein the DC/DC converter circuit comprises a forward converter.

28. A UPS system according to claim 22, further comprising a current control circuit configured to be coupled between the output port and at least one of the rectifier circuit and the DC/DC converter circuit and operative to control a current from the at least one of the rectifier circuit and the DC/DC converter circuit responsive to a control input.

29. A UPS system according to claim 28, wherein the current control circuit comprises a power factor correction circuit.

30. A UPS system according to claim 22, further comprising a DC power source connected to the DC input port.

31. A UPS system according to claim 22 in combination with an AC load coupled to the output port.

32. A UPS system according to claim 22, wherein the control input comprises at least one of a voltage at the AC input port, a current at the AC input port, a voltage at the DC input port, and a voltage at the output port.

33. An uninterruptible power supply system, comprising:

a plurality of UPS subsystems, the UPS subsystems each comprising;

an AC input port;

a DC input port;

an output port configured to be directly connected to an AC load;

a rectifier circuit coupled to the AC input port; and

a power transfer control circuit coupled to the rectifier circuit, the DC input port and the output port, the power transfer control circuit operative to produce a DC voltage at the output port from a rectified voltage produced by the rectifier circuit in a first mode of operation and to produce a DC voltage at the output port from a DC voltage at the DC input port in a second mode of operation,

wherein the plurality of UPS subsystems are configured to be connected in common at their output ports to a load including at least one AC load.

34. A UPS system according to claim 33, wherein the power transfer control circuit comprises a current control circuit configured to be connected between the output port and at least one of the rectifier circuit and the DC input port and operative to control a current from the at least one of the rectifier circuit and the DC input port responsive to a control input.

35. A UPS system according to claim 34, wherein the respective current control circuits of the UPS subsystems are operative to control respective power factors at their respective AC input ports.

36. A UPS system according to claim 34, wherein the respective current control circuits comprise respective boost regulator circuits.

37. A UPS system according to claim 34, wherein the respective current control circuits are further operative to regulate voltages at the respective output ports.

38. A UPS system according to claim 34, wherein the current control circuits are operative to control current vs. voltage characteristics at the output ports to provide a desired current sharing among the UPS subsystems.

39. A UPS system according to claim 34, wherein the respective power transfer control circuits comprise respective switching circuits operative to decouple the respective DC input ports from the respective current control circuits in the first mode of operation and to couple the respective DC input ports to the respective current control circuits in the second mode of operation.

40. A UPS system according to claim 34, wherein the control input comprises at least one of a voltage at the AC input port, a current at the AC input port, a voltage at the DC input port and a voltage at the output port.

41. A UPS system according to claim 33, wherein the UPS subsystems have capacities sufficient to provide redundant power supply service to the load.

42. A UPS system according to claim 41, wherein the UPS subsystems have capacities sufficient to provide N+1 redundancy.

43. A UPS system according to claim 33, wherein the power transfer control circuit comprises:

a DC/DC converter circuit coupled to the DC input port; and

a switching circuit operative to couple and decouple the DC/DC converter circuit to and from the output port.

44. A UPS system according to claim 33, wherein the DC/DC converter circuit provides galvanic isolation between the DC input port and the output port in the second mode of operation.

45. A UPS system according to claim 33, wherein the DC/DC converter circuit comprises an open-loop converter.

46. A UPS system according to claim 33, further comprising at least one DC power source connected to the DC input ports of the UPS subsystems.

55. A method according to claim 46, wherein the DC power source comprises a battery.

47. A method of supplying power to an AC load, the method comprising:

applying an AC voltage to a rectifier circuit to produce a rectified voltage;

controlling a current from the rectifier circuit while producing a DC voltage at the AC load from the rectified voltage; and

then

coupling a DC power source to the AC load to produce a DC voltage at the AC load from the DC power source.

48. A method according to claim 47, further comprising the step of decoupling the DC power source from the AC load concurrent with the step of controlling a current from the rectifier circuit while producing an AC voltage at the AC load from the rectified voltage.

49. A method according to claim 48, wherein the step coupling a DC power source to the AC load to produce a DC voltage at the AC load comprising coupling the DC power source to the AC load responsive to the AC voltage meeting a predetermined criterion.

50. A method according to claim 47, wherein the step of controlling a current from the rectifier circuit while producing a DC voltage at the AC load from the rectified voltage comprises controlling at least one of a power factor and a harmonic current at an AC source producing the AC voltage.

51. A method according to claim 50, wherein the step of controlling a current from the rectifier circuit while producing a DC voltage at the AC load from the rectified voltage further comprises regulating the DC voltage produced at the AC load from the rectified voltage.

52. A method according to claim 47, wherein the step of controlling a current from the rectifier circuit while producing a DC voltage at the AC load from the rectified voltage comprises regulating the DC voltage produced at the AC load from the rectified voltage.

53. A method according to claim 47, further comprising controlling a current from the DC power source while producing the DC voltage at the AC load from the DC power source.

54. A method according to claim 53, wherein the step of controlling a current from the DC power source while producing the DC voltage at the AC load from the DC power source comprises regulating the DC voltage produced at the AC load from the DC power source.

56. A method according to claim 47, further comprising the step of providing galvanic isolation between the DC power source and the AC load concurrent with the step of coupling the DC power source to the AC load to produce a DC voltage at the AC load from the DC power source.

57. A method of supplying power to an AC load, the method comprising:

applying an AC voltage to a rectifier circuit to produce a rectified voltage;

applying a DC voltage to a DC/DC converter circuit to produce a converted DC voltage;

producing a DC voltage at the AC load from the rectified voltage; and

then

producing a DC voltage at the AC load from the converted DC voltage.

58. A method according to claim 57, wherein the step of applying a DC voltage to a DC/DC converter circuit comprises generating a boosted DC voltage from the applied DC voltage at the DC input port.

59. A method according to claim 57, further comprising providing galvanic isolation between the DC input port and the output port while transferring power between the DC input port and the output port.

60. A method according to claim 57, wherein the DC/DC converter circuit comprises an open-loop converter.

61. A method according to claim 57, wherein the DC/DC converter circuit comprises a forward converter.

62. A method according to claim 57, further comprising controlling a current from at least one of the rectifier circuit and the DC/DC converter circuit responsive to a control input.

63. A method according to claim 62, wherein the control input comprises at least one of a voltage at the AC input port, a current at the AC input port, a voltage at the DC input port, and a voltage at the output port.

64. A method according to claim 57, further comprising controlling at least one of power factor and a harmonic current at the AC input port concurrent with the step of producing a DC voltage at the AC load from the rectified voltage.