Power conversion apparatus and methods using balancer circuits

• US 6,819,576 B2
• Filed: 03/25/2002
• Issued: 11/16/2004
• Est. Priority Date: 08/13/1999
• Status: Expired due to Term

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Powerware Corporation (Eaton Corporation PLC.)
• Inventors: Johnson, Robert W. Jr.
• Primary Examiner(s): Vu, Bao Q.
• Application Number:
  US10/106,943
• Publication Number:
  US 20020109412A1
• Time in Patent Office: 967 Days
• Field of Search: 363/17, 363/34, 363/37, 363/58, 363/98, 363/132, 363/123, 363/142, 307/66
• US Class Current: 363/123
• CPC Class Codes: H02J 9/061 for DC powered loads
• CPC Class Codes: H02J 9/062 for AC 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
• CPC Class Codes: H02M 5/4585 having a rectifier with controlled elements
• CPC Class Codes: H02M 7/538 in a push-pull configuration H02M7/5375 takes precedence ; with oscillating arrangements H02M7/53832, H02M7/53846

Abstract

A power conversion apparatus, such as an uninterruptible power supply (UPS), includes an input port, an output port, and first and second busses. An output circuit, for example, a half-leg inverter, is coupled to the first and second busses and to the output port and operative to transfer power therebetween. An auxiliary DC voltage generator circuit, for example, a battery converter circuit, is operative to generate DC voltages on the first and second busses. A multifunction rectifier circuit is coupled to the input port and to the first and second busses, the multifunction rectifier circuit operative to generate DC voltages on the first and second busses from an AC power source at the input port when the apparatus is operating in a first mode (e.g., an AC powered operational mode). The multifunction rectifier circuit is operative to control relative magnitudes of the DC voltages generated by the auxiliary DC voltage generator circuit when the apparatus is operating in a second mode (e.g., a battery-powered operational mode). Related power conversion methods are described.

Claims

1. A power conversion apparatus, comprising:

an input port;

an output port;

first and second busses;

an output circuit coupled to the first and second busses and to the output port and operative to transfer power therebetween;

an auxiliary DC voltage generator circuit operative to generate DC voltages on the first and second busses; and

a multiflinction rectifier circuit coupled to the input port and to the first and second busses, the multifunction rectifier circuit operative to generate DC voltages on the first and second busses from an AC power source at the input port when the apparatus is operating in a first mode and to control relative magnitudes of the DC voltages generated by the auxiliary DC voltage generator circuit when the apparatus is operating in a second mode.

2. An apparatus according to claim 1, wherein the multifunction rectifier circuit comprises:

an inductor having first and second terminals;

a first switch operative to couple and decouple the first voltage bus to and from the first terminal of the inductor;

a second switch operative to couple and decouple the second voltage bus to and from the first terminal of the inductor; and

a third switch operative to couple the second terminal of the inductor to the input port in a first switch state and to couple the second terminal of the inductor to a reference voltage bus for the first and second busses in a second switch state.

3. An apparatus according to claim 2, wherein the third switch is operative to couple the second terminal of the inductor to a phase terminal of the input port in the first switch state and to couple the second terminal of the inductor to a neutral terminal of the input port in the second switch state.

4. An apparatus according to claim 1, wherein the multifunction rectifier circuit is operative to selectively control relative magnitudes of the DC voltages generated by the auxiliary DC voltage generator circuit when the apparatus is operating in the second mode.

5. An apparatus according to claim 4, wherein the multifunction rectifier circuit is operative to commence controlling relative magnitudes of the DC voltages generated by the auxiliary DC voltage generator circuit responsive to at least one voltage on at least one of the first and second busses.

6. An apparatus according to claim 1, wherein the auxiliary DC voltage generator circuit comprises a battery converter circuit having a battery input port configured to be coupled to a battery and an output port coupled to the first and second busses.

7. An apparatus according to claim 6, wherein the battery converter circuit comprises:

an inverter circuit coupled to the battery input port;

a transformer having a primary winding coupled to the inverter; and

a rectifier circuit coupled between a secondary winding of the transformer and the first and second busses.

8. An apparatus according to claim 1, wherein the output circuit comprises a half-leg inverter circuit.

9. An uninterruptible power supply apparatus, comprising:

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

a battery input port configured to be coupled to a battery;

an output port configured to be coupled to a load;

first and second busses;

a half-leg inverter circuit coupled to the first and second busses arid to the output port;

a battery converter circuit coupled to the battery input port and the first and second busses; and

a multifunction rectifier circuit coupled to the AC input port and the first and second busses, the multifunction rectifier circuit operative to generate DC voltages on the first and second busses when the apparatus is operating in a first mode and to control relative magnitudes of DC voltages generated by the battery converter circuit on the first and second busses when the apparatus is operating in a second mode.

10. An apparatus according to claim 9, wherein the battery converter circuit is operative to provide unidirectional power transfer from the battery to the first and second busses.

11. An apparatus according to claim 9, wherein the battery converter circuit comprises:

an inverter circuit coupled to the battery input port;

a transformer having a primary winding coupled to the inverter; and

a rectifier circuit coupled between a secondary winding of the transformer and the first and second busses.

12. An apparatus according to claim 9, wherein the multifunction rectifier circuit comprises:

an inductor having first and second terminals;

a first switch operative to couple and decouple the first voltage bus to and from the first terminal of the inductor;

a second switch operative to couple and decouple the second voltage bus to and from the first terminal of the inductor; and

a third switch operative to couple the second terminal of the inductor to the input port in a first switch state and to couple the second terminal of the inductor to a reference voltage bus for the first and second busses in a second switch state.

13. An apparatus according to claim 12, wherein the third switch is operative to couple the second terminal of the inductor to a phase terminal of the AC input port in the first switch state and to couple the second terminal of the inductor to a neutral terminal of the AC input port in the second switch state.

14. An apparatus according to claim 12, wherein the multifunction rectifier circuit is operative to intermittently control relative magnitudes of the DC voltages generated by the battery convener circuit when the apparatus is operating in the second mode.

15. An apparatus according to claim 14, wherein the multifunction rectifier circuit is operative to commence controlling relative magnitudes of the DC voltages generated by the battery converter circuit responsive to at least one voltage on at least one of the first and second busses.

16. A power conversion apparatus, comprising:

first and second busses;

a DC voltage generator circuit operative to generate DC voltages on the first and second busses;

an AC output circuit coupled to the first and second busses and operative to generate an AC output voltage from DC voltages on the first and second busses; and

a balancer circuit operative to control relative magnitudes of DC voltages on the first and second busses by selectively coupling the first and second busses to a reference bus via an inductor.

17. An apparatus according to claim 16, wherein the balancer circuit is operative to control relative magnitudes of DC voltages produced by the DC voltage generator circuit in a first mode of operation and wherein the balancer circuit is operative to generate DC voltages on the first and second busses from an AC power source in a second mode of operation.

18. An apparatus according to claim 17, wherein the balancer circuit comprises a rectifier circuit.

19. An apparatus according to claim 18, wherein the rectifier circuit comprises:

an inductor;

first and second switches operative to couple and decouple respective ones of the first and second busses to the reference bus via the inductor.

20. An apparatus according to claim 17, wherein the DC voltage generator circuit comprises a battery converter circuit.

21. An apparatus according to claim 16, wherein the reference bus comprises a ground reference bus.

22. A power conversion method comprising:

causing a rectifier circuit to produce DC voltages on first and second busses from an AC power source coupled to the rectifier circuit;

producing DC voltages on the first and second busses from a secondary power source; and

operating the rectifier circuit to control relative magnitudes of the DC voltages produced from the secondary power source.

23. A method according to claim 22, further comprising producing an AC voltage from DC voltages on the first and second busses.

24. A method according to claim 22, wherein operating the rectifier circuit to control relative magnitudes of the DC voltages produced from the secondary power source comprises alternately coupling ones of the first and second voltage busses to a reference bus.

25. A method according to claim 24, wherein alternately coupling ones of the first and second voltage busses to a reference bus comprises alternately coupling ones of the first and second voltage busses to the reference bus via an inductor.

26. A method according to claim 22, wherein operating the rectifier circuit to control relative magnitudes of the DC voltages produced from the secondary power source comprises operating the rectifier circuit to control relative magnitudes of the DC voltages produced from the secondary power source responsive to at least one voltage on at least one of the first and second busses.

27. A method according to claim 26, wherein operating the rectifier circuit to control relative magnitudes of the DC voltages produced from the secondary power source responsive to at least one voltage on at least one of the first and second busses comprises refraining from operating the rectifier circuit to control relative magnitudes of the DC voltages produced from the secondary power source until the at least one voltage meets a predetermined criterion.

28. A method according to claim 22, wherein the rectifier circuit comprises an inductor having first and second terminals, a first switch operative to couple and decouple the second terminal of the inductor to and from the first bus, and a second switch operative to couple and decouple the second terminal of the inductor to and from the second bus, and wherein operating the rectifier circuit to control relative magnitudes of the DC voltages produced from the secondary power source comprises:

connecting the first terminal of the inductor to a reference bus; and

operating the first and second switches in a substantially complementary fashion.

29. A method according to claim 28, wherein the reference bus is connected to a neutral terminal of the AC power source.

30. A power conversion method comprising:

producing DC voltages on first and second busses from a power source;

selectively coupling the first and second busses to a reference bus via an inductor to control relative magnitudes of the DC voltages; and

producing an AC output voltage from DC voltages on the first and second busses.

31. A method according to claim 30, wherein producing DC voltages on first and second busses from a power source comprises producing the DC voltages from a battery power source.

32. A method according to claim 31, wherein selectively coupling the first and second busses to a reference bus via an inductor to control relative magnitudes of the DC voltages comprises operating switches of a rectifier circuit having an input configured to be selectively coupled to an AC input port and the reference bus.

33. A method according to claim 30, wherein the reference bus comprises a ground reference bus.

34. A method according to claim 33, wherein the ground reference bus is connected to a neutral terminal of the power source.

35. A power conversion apparatus comprising:

means for producing DC voltages on first and second busses from a power source;

means for selectively coupling the first and second busses to a reference bus via an inductor to control relative magnitudes of the DC voltages; and

means for producing an AC output voltage from DC voltages on the first and second busses.

36. An apparatus according to claim 35, wherein the means for producing DC voltages on first and second busses from a power source comprises means for producing the DC voltages from a battery power source.

37. An apparatus according to claim 35, wherein the means for selectively coupling the first and second busses to a reference bus via an inductor to control relative magnitudes of the DC voltages comprises means for operating switches of a rectifier circuit having an input configured to be selectively coupled to an AC input port and the reference bus.

38. An apparatus according to claim 35, wherein the reference bus comprises a ground reference bus.

39. An apparatus according to claim 38, wherein the ground reference bus is connected to a neutral terminal of the power source.

40. A power converter, comprising:

first and second voltage busses;

a neutral bus;

first and second capacitors coupling respective ones of the first and second voltage busses to the neutral bus;

a first switching circuit operative to selectively couple an input node thereof to the first and second voltage busses;

a balancer circuit operative to selectively couple the neutral bus to the first and second voltage busses; and

a second switching circuit operative to selectively couple the first and second voltage busses to a load connected at an output node thereof.

41. A converter according to claim 40, wherein the balancer circuit selectively couples the first and second voltage busses to the neutral bus responsive to at least one of a voltage at the input node of the first switching circuit and a voltage at the output node of the second switching circuit.

42. A method according to claim 40, wherein the balancer circuit is operative to selectively couple the neutral bus to the first and second voltage busses such that relative magnitudes of respective ones of first and second voltages on the first and second voltage busses with respect to the neutral are constrained to be approximately equal.

43. A method of controlling power transfer between an AC power source and a load, the method comprising the steps of:

selectively coupling first and second voltage busses to a phase bus of the AC power source through a first inductance to produce first and second DC voltages at the first and second voltage busses, respectively;

selectively coupling the first and second voltage busses to the load through a second inductance; and

selectively coupling the first and second voltage busses to a neutral bus of the load through a third inductance such that relative magnitudes of the first and second DC voltages across respective first and second capacitors that couple the respective first and second DC voltage busses to the neutral bus are controlled responsive to respective first and second rates at which the first and second voltage busses are coupled to the neutral bus.

44. A method according to claim 43, wherein selectively coupling the first and second voltage busses to a neutral bus of the load through a third inductance comprises selectively coupling the first and second voltage busses to the neutral bus responsive to at least one of an AC voltage of the AC power source and an AC voltage at the load.

45. An uninterruptible power supply, comprising:

first and second busses;

a DC voltage generator circuit operative to generate DC voltages on the first and second busses;

an AC output circuit coupled to the first and second busses and operative to generate an AC output voltage from DC voltages on the first and second busses; and

a balancer circuit operative to control relative magnitudes of DC voltages on the first and second busses by selectively coupling the first and second busses to a reference bus via an inductor.

46. An uninterruptible power supply according to claim 45, wherein the DC voltage generator circuit comprises:

a rectifier circuit operative to generate DC voltages on the first and second busses from an AC power source; and

a secondary DC power source operative to generate DC voltages on the first and second busses responsive to failure of the AC power source.