Power factor corrected UPS with improved connection of battery to neutral

• US 6,400,586 B2
• Filed: 03/20/2001
• Issued: 06/04/2002
• Est. Priority Date: 03/29/1993
• Status: Expired due to Term

• Current Assignee: Eaton Power Quality Corporation (Eaton Corporation PLC.)
• Original Assignee: Powerware Corporation (Eaton Corporation PLC.)
• Inventors: Johnson, Robert W. Jr., Raddi, William J., Paulakonis, Joseph C.
• Primary Examiner(s): Vu, Bao Q.
• Application Number:
  US09/812,993
• Publication Number:
  US 20010012209A1
• Time in Patent Office: 441 Days
• Field of Search: 363/17, 363/40, 363/41, 363/37, 363/47, 363/48, 363/95, 363/98, 363/131, 363/132, 307/64, 307/66
• US Class Current: 363/37
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/4208 Arrangements for improving power factor of AC input
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

An uninterrupted power supply (UPS) device with uninterrupted neutral from input to output utilizes the same converter for converting rectified AC power and battery power to positive and negative high voltage (HV) rails. A simple circuit is utilized for connecting the battery to the conversion components of the PFC circuit without adverse affect on the performance of the PFC circuit, and while holding the battery substantially connected to neutral. In a first embodiment, the circuit comprises a simple combination of four diodes and a pair of high pass capacitors arranged so that in both power line and battery supply modes the battery is balanced around neutral. In a second, preferred embodiment, one terminal of the battery is connected directly to neutral.

Claims

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

a power factor correcting converter circuit, configured to connect to an AC power source and to a battery, that generates a DC output voltage from the AC power source in an AC powered mode and that generates the DC output voltage from the battery in a DC powered mode.

2. An apparatus according to claim 1, further comprising:

an output circuit, electrically coupled to the power factor correcting converter circuit, that generates an AC output voltage at a load from the DC output voltage; and

a neutral connecting the AC power source and the load.

3. An apparatus according to claim 2, wherein the power factor correcting converter circuit and the output circuit produce the AC output voltage without isolating the load from the AC power source.

4. An apparatus according to claim 2, wherein the output circuit comprises an inverter.

5. An apparatus according to claim 1, wherein the power factor correcting circuit generates the DC output voltage from the AC power source in the AC powered mode and from the battery in the battery powered mode using a common inductor and a common switching circuit.

6. An apparatus according to claim 1:

wherein the power factor correcting converter circuit produces the DC output voltage at a DC output port including first and second DC output nodes; and

wherein the power factor correcting converter circuit includes a first inductor electrically coupled to the first DC output node and a second inductor electrically coupled to the second DC output node, wherein the power factor correcting converter circuit in the AC powered mode increases and decreases current through the first and second inductors from the AC power source port responsive to a first input to generate the DC output voltage, and wherein the power factor correcting converter circuit in the battery powered mode increases and decreases current through the first and second inductors from the battery responsive to a second input to generate the DC output voltage.

7. An apparatus according to claim 6, wherein the power factor correcting converter circuit selectively couples the first and second inductors to the AC power source and the battery responsive to a third input.

8. An apparatus according to claim 7, wherein the power factor correcting converter circuit selectively couples the first and second inductors to the AC power source and the battery responsive to an AC input voltage at the AC input port.

9. An apparatus according to claim 6, wherein the power factor correcting converter circuit switches respective shunt paths between respective ones of the first and second inductors and the AC power source to charge a capacitance coupled to the DC output port in the AC powered mode, and wherein the power factor correcting converter circuit switches respective shunt paths between respective ones of the first and second inductors and the battery to charge the capacitance at the DC output port in the DC powered mode.

10. A power conversion apparatus, comprising:

an AC input port;

first and second voltage rails;

a DC input port;

an output port;

a power factor correcting converter circuit having an input and an output that is connected to the first and second voltage rails, wherein the power factor correcting converter circuit generates a DC voltage across the first and second voltage rails from a voltage at the input of the power factor correcting converter circuit; and

a connection circuit, coupled to the AC input port, to the DC input port and to the input of the power factor correcting converter circuit, that selectively couples the AC input port and the DC input port to the input of the power factor correcting converter circuit.

11. An apparatus according to claim 10, further comprising an output circuit, coupled to the first and second DC voltage rails, that produces an AC output voltage at an AC output port from respective first and second DC voltages at the first and second voltage rails, wherein the power factor correcting converter circuit and the output circuit maintain neutral integrity between the AC input port and the AC output port.

12. An apparatus according to claim 10, wherein the connection circuit selectively couples the AC input port and the DC input port to the input of the power factor correcting converter circuit responsive to an AC input voltage at the AC input port.

13. An apparatus according to claim 10, wherein the power factor correcting converter circuit produces respective DC voltages at the first and second voltage rails from an AC input voltage at the AC input port when the AC input voltage is in a first state, and wherein the power factor correcting converter circuit produces respective DC voltages at the first and second voltage rails from a DC input voltage at the DC input port when the AC input voltage is in a second state.

14. An apparatus according to claim 13:

wherein the AC input port comprises first and second AC input nodes;

wherein the power factor correcting converter circuit comprises;

a first inductor having a first node coupled to the first voltage rail; and

a second inductor having a first node coupled to the second voltage rail; and

wherein the connection circuit, when the AC input voltage is in the first state, is operative to couple a second node of the first inductor to the first AC input node and to couple a second node of the second inductor to the first AC input node; and

wherein the power factor correcting converter circuit, when the AC input voltage is in the first state, is operative to couple and decouple the first node of the first inductor to and from the second AC input node, and to couple and decouple the first node of the second inductor to and from the second AC input node.

15. An apparatus according to claim 14:

wherein the DC input port comprises first and second DC input nodes; and

wherein the connection circuit, when the AC input voltage is in the second state, is operative to couple the second node of the first inductor to the first DC input node and to couple the second node of the second inductor to the second DC input node; and

wherein the power factor correcting converter circuit, when the AC input voltage is in the second state, is operative to couple and decouple the first node of the first inductor to and from the second DC input node, and to couple and decouple the second node of the second inductor to and from the first DC input node.

16. An apparatus according to claim 10, further comprising an output circuit, coupled to the first and second DC voltage rails, that produces an AC output voltage from respective first and second DC voltages at the first and second voltage rails.

17. An apparatus according to claim 10, further comprising a battery coupled to the DC input port.

18. A power conversion apparatus, comprising:

an AC input port;

a DC input port;

a DC output port including first and second DC output nodes; and

a power factor correcting converter circuit including a first inductor electrically coupled to the first DC output node and a second inductor electrically coupled to the second DC output node, wherein the power factor correcting converter circuit in an AC powered mode increases and decreases current through the first and second inductors from the AC input port responsive to a first input to generate a DC output voltage at the DC output port from an AC power source at the AC input port, and wherein the power factor correcting converter circuit in a DC powered mode increases and decreases current through the first and second inductors from the DC input port responsive to a second input to generate a DC output voltage at the DC output port from a DC power source at the DC input port.

19. An apparatus according to claim 18, further comprising an output circuit, coupled to the DC output port, that produces an AC output voltage at an AC output port from a DC voltage at the DC output port, and wherein the power factor correcting converter circuit and the output circuit maintain neutral integrity between the AC input port and the AC output port.

20. An apparatus according to claim 18, wherein the converter circuit selectively couples the first and second inductors to the AC input port and the DC input port responsive to a third input.

21. An apparatus according to claim 20, wherein the converter circuit selectively couples the first and second inductors to the AC input port and the DC input port responsive to an AC input voltage at the AC input port.

22. An apparatus according to claim 20, wherein the power factor correcting converter circuit switches respective shunt paths between respective ones of the first and second inductors to the AC input port to charge a capacitance coupled to the DC output port in the AC powered mode, and wherein the power factor correcting converter circuit switches respective shunt paths between respective ones of the first and second inductors and the DC input port to charge the capacitance at the DC output port in the DC powered mode.

23. An apparatus according to claim 18, further comprising a capacitor coupled to the DC output port, and wherein the power factor correcting converter circuit switches respective shunt paths between respective ones of the first and second inductors and the AC input port to charge the capacitor in the AC powered mode, and wherein the power factor correcting converter circuit switches respective shunt paths between respective ones of the first and second inductors from the AC input port to charge the capacitor in the DC powered mode.

24. An apparatus according to claim 18:

wherein a first node of the first inductor is coupled to the first DC output node;

wherein a first node of the second inductor is coupled to the second DC output node; and

wherein the power factor correcting converter circuit comprises;

a first current control circuit, coupled to the first DC input node and to a second node of the first inductor, that passes current between the first DC input node and the second node of the first inductor in the DC powered mode;

a second current control circuit, coupled to the second DC input node and to a second node of the second inductor, that passes current between the second node of the second inductor and the second DC input node in the DC powered mode;

a first switch that couples and decouples the first node of the first inductor and the second DC input node responsive to a first control signal in the DC powered mode; and

a second switch that couples and decouples the first node of the second inductor and the first DC input node responsive to a second control signal in the DC powered mode.

25. An apparatus according to claim 24:

wherein the first current control circuit inhibits current flow from the second node of the first inductor to the first DC input node in the AC powered mode;

wherein the second current control circuit inhibits current flow from second node of the second inductor to the second DC input node in the AC powered mode; and

wherein the first switch couples and decouples the first node of the first inductor to the second AC input node responsive to a third control signal in the AC powered mode.

26. An apparatus according to claim 25, wherein the second switch couples and decouples the first node of the second inductor to the second AC input node responsive to a fourth control signal in the AC powered mode.

27. An apparatus according to claim 24, wherein the first and second current control circuits comprise respective first and second diodes that couple respective ones of the first and second DC input nodes to respective ones of the second nodes of the first and second inductors.

28. An apparatus according to claim 24, wherein at least one of the first and second current control devices comprises a third switch.

29. An apparatus according to claim 18, further comprising a battery coupled to the DC input port.

30. An apparatus according to claim 18, further comprising an inverter coupled to the DC output port.

31. A power conversion apparatus, comprising:

an AC input port;

a DC input port;

a DC output port; and

a power factor correcting converter circuit including an inductor coupled to the DC output port, wherein the power factor correcting converter circuit has a AC powered mode in which the power factor correcting converter circuit increases and decreases current through the inductor from the AC input port responsive to a first input to generate a DC output voltage at the DC output port from an AC power source at the AC input port, and wherein the power factor correcting converter circuit has a DC powered mode in which the converter increases and decreases current through the inductor from the DC input port responsive to a second input to generate a DC output voltage at the DC output port from a DC power source at the DC input port.

32. An apparatus according to claim 31, further comprising an output circuit, coupled to the DC output port, that produces an AC output voltage at an AC output port from a DC voltage at the DC output port, wherein the power factor correcting converter circuit and the output circuit maintain neutral integrity between the AC input port and the AC output port.

33. An apparatus according to claim 31, wherein the power factor correcting converter circuit selectively couples the inductor to the AC input port and the DC input port responsive to a third input.

34. An apparatus according to claim 33, wherein the power factor correcting converter circuit selectively couples the inductor to the AC input port and the DC input port responsive to an AC input voltage at the AC input port.

35. An apparatus according to claim 31, wherein the power factor correcting converter circuit switches a shunt path between the inductor and the AC input port to charge a capacitance coupled to the DC output port in the AC powered mode, and wherein the power factor correcting converter circuit switches a shunt path between the inductor and the DC input port to charge the capacitance in the DC powered mode.

36. An apparatus according to claim 31, further comprising a capacitor coupled across the DC output port, and wherein the power factor correcting converter circuit switches a shunt path between the inductor and the AC input port to charge the capacitor in the AC powered mode, and wherein the power factor correcting converter circuit switches a shunt path between the inductor and the DC input port to charge the capacitor in the DC powered mode.

37. An apparatus according to claim 31:

wherein the DC output port comprises first and second DC output nodes;

wherein the inductor has a first node electrically coupled to the first DC output node; and

wherein the power factor correcting converter circuit further comprises;

a current control circuit, coupled to the first DC input node and a second node of the inductor, that passes current between the first DC input node and the second node of the inductor in the DC powered mode; and

a switch that couples and decouples the first node of the inductor and the second DC input node responsive to a control signal in the DC powered mode.

38. An apparatus according to claim 37:

wherein the current control circuit inhibits current flow from the second node of the inductor to the first DC input node in the AC powered mode; and

wherein the switch couples and decouples the first node of the inductor to the second AC input node responsive to the control signal in the AC powered mode.

39. An apparatus according to claim 38, wherein the current control circuit comprises a diode that couples the first DC input node to the second node of the inductor.

40. An apparatus according to claim 38, wherein the current control circuit comprises a second switch that controls current flow between the first DC input terminal and the second terminal of the inductor.

41. A power conversion circuit comprising:

an AC input port including first and second AC input nodes;

a DC input port including first and second DC input nodes;

a DC output port including first and second DC output nodes;

a first inductor having a first node electrically coupled to the first DC output node;

a second inductor having a first node electrically coupled to the second DC output port;

a first current control circuit, electrically coupled to the first AC input node, the first DC input node and a second node of the first inductor, that controls current flow between the first AC input node and the second node of the first inductor and current flow between the first DC input node and the second node of the inductor responsive to an input;

a second current control circuit, electrically coupled to the second AC input node, the second DC input node and the second node of the second inductor, that controls current flow between the second AC input node and the second node of the second inductor and current flow between the second DC input node and the second node of the second inductor responsive to the input;

a first switching circuit that selectively couples and decouples the first node of the first inductor to and from at least one of the second DC input node and the second AC input node responsive to a first control signal;

a second switching circuit that selectively couples and decouples the first node of the second inductor to and from at least one of the first DC input node and the second AC input node responsive to a second control signal; and

a control circuit that generates the first and second control signals such that a desired power factor is maintained at the AC input port.

42. A circuit according to claim 41, further comprising:

an output circuit, coupled to the DC output port, that produces an AC output voltage at an AC output port from a DC voltage at the DC output port; and

a neutral connection between the AC input port and the AC output port.

43. A circuit according to claim 41:

wherein the first switching circuit is electrically coupled to the first current control circuit through the first inductor; and

wherein the second switching circuit is electrically coupled to the second current control circuit through the second inductor.

44. A circuit according to claim 41:

wherein the first current control circuit passes current between the first DC input node and the second node of the first inductor while inhibiting current flow between the first AC input node and the second node of the first inductor responsive to a first state of the input;

wherein the first current control circuit passes current between the first AC input node and the second node of the first inductor while inhibiting current flow between the first DC input node and the second node of the inductor responsive to a second state of the input;

wherein the second current control circuit passes current between the second node of the second inductor and the second DC input node while inhibiting current flow between the second node of the inductor and the second DC input node responsive to the first state of the input; and

wherein the second current control circuit inhibits current flow between the second node of the second inductor and the second DC input node responsive to the second state of the input.

45. A circuit according to claim 41, wherein the input comprises an AC input voltage at the AC input port.

46. A power conversion circuit, comprising:

an AC input port including an AC input node and a common node;

a DC input port including a DC input node and the common node;

a DC output port including a DC output node and the common node;

an inductor having a first node electrically coupled to the DC output node;

a current control circuit, electrically coupled to the AC input node, the DC input node and a second node of the inductor, that controls current flow between the AC input node and the second node of the inductor and current flow between the DC input node and the second node of the inductor responsive to an input;

a switching circuit that selectively couples and decouples the first node of the inductor and the common node responsive to a control signal; and

a control circuit that generates the control signal such that operation of the switching circuit maintains a desired power factor at the AC input port.

47. A circuit according to claim 46, further comprising:

an output circuit, coupled to the DC output port, that produces an AC output voltage at an AC output port from a DC voltage at the DC output port; and

a neutral connection between the AC input port and the AC output port.

48. A circuit according to claim 46, wherein the switching circuit is electrically coupled to the current control circuit through the inductor.

49. A circuit according to claim 46:

wherein the current control circuit passes current between the DC input node and the second node of the inductor while inhibiting current flow between the AC input node and the second node of the inductor responsive to a first state of the input; and

wherein the current control circuit passes current between the AC input node and the second node of the inductor while inhibiting current flow between the DC input node and the second node of the inductor responsive to a second state of the input.

50. A circuit according to claim 46, wherein the input comprises an AC input voltage at the AC input port.

51. A method of operating a power converter including an AC input port, a DC input port, a DC output port, a first inductor electrically coupled to a first DC output node of the DC output port, and a second inductor electrically coupled to a second DC output node of the DC output port, the method comprising:

increasing and decreasing current through the first and second inductors from an AC power source at the AC input port responsive to a first input to generate a DC output voltage at the DC output port from the AC power source and to control a power factor at the AC input port; and

increasing and decreasing current through the first and second inductors from a DC power source at the DC input port responsive to a second input to generate a DC output voltage at the DC output port from the DC power source.

52. A method according to claim 51, further comprising generating an AC output voltage at an AC output port from the DC voltage generated at the DC output port from the AC power source while maintaining neutral integrity between the AC input port and the AC output port.

53. A method according to claim 51, wherein the first and second inputs comprise first and second conditions of an AC input voltage.

54. A method according to claim 51:

wherein increasing and decreasing current through the first and second inductors from an AC power source at the AC input port responsive to a first input comprises switching respective shunt paths between respective ones of the first and second inductors and the AC power source responsive to a first control signal to charge a capacitance at the DC output port; and

wherein increasing and decreasing current through the first and second inductors from a DC power source at the DC input port responsive to a second input comprises switching respective shunt paths between respective ones of the first and second inductors and the DC power source responsive to a second control signal to charge the capacitance at the DC output port.

55. A method of operating a power converter having an AC power source coupled to an AC input port, a DC power source coupled to a DC input port, and an inductor coupled to a DC output port, the method comprising:

increasing and decreasing a current through the inductor from the AC input port responsive to a first input to generate a DC output voltage at the DC output port from an AC power source at the AC input port and to control a power factor at the AC input port; and

increasing and decreasing a current through the inductor from the DC input port responsive to a second input to generate a DC output voltage at the DC output port from a DC power source at the DC input port.

56. A method according to claim 55, further comprising generating an AC output voltage at an AC output port from the DC voltage generated at the DC output port from the AC power source while maintaining neutral integrity between the AC input port and the AC output port.

57. A method according to claim 55, wherein the first and second inputs comprise first and second conditions of a voltage at the AC input port.

58. A method according to claim 55:

wherein increasing and decreasing a current through the inductor from the AC input port responsive to a first input comprises switching a shunt path between the inductor and the AC input port to charge a capacitance across the DC output port;

wherein increasing and decreasing a current through the inductor from the DC input port responsive to a second input comprises switching a shunt path between the inductor and the DC input port to charge the capacitance across the DC output port in the DC powered mode.

59. A method of operating a power converter coupled to an AC power source at an AC input port including first and second AC input nodes and coupled to a DC power source at first and second DC input nodes, the method comprising:

coupling the first AC input node to an output node via an inductor and decoupling the first DC input node from the inductor while intermittently coupling the output node to the second AC input node to generate a DC output voltage at the output node from the AC power source and to correct a power factor at the AC port; and

coupling the first DC input node to the output node via the inductor and decoupling the first AC input node from the inductor while intermittently coupling the output node to the second DC input node to generate a DC output voltage at the output node from the DC power source.

60. A method according to claim 59, further comprising generating an AC output voltage across first and second AC output nodes from the DC output voltage generated from the AC power source while maintaining neutral integrity between the second AC input node and the second AC input node.

61. A method according to claim 59, wherein the second node of the AC power source is coupled to the second node of the DC power source.