Efficient power conversion

• US 5,786,992 A
• Filed: 07/29/1996
• Issued: 07/28/1998
• Est. Priority Date: 04/08/1994
• Status: Expired due to Term

• Current Assignee: VLT Incorporated (Vicor Corporation)
• Original Assignee: VLT Incorporated (Vicor Corporation)
• Inventors: Beede, Richard E., Vinciarelli, Patrizio
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US08/681,618
• Time in Patent Office: 729 Days
• Field of Search: 363/20, 363/21, 363/34, 363/39, 363/65, 363/67, 363/69, 363/70, 363/89, 363/101, 363/123, 363/131, 323/223, 323/224, 323/225
• US Class Current: 363/89
• CPC Class Codes: H02J 1/102 being switching converters H02J1/108, H02J1/12 take precedence
• 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 1/4208 Arrangements for improving power factor of AC input
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/28 using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
• 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

In a power conversion scheme, a power conversion apparatus consisting of boost conversion elements for effecting a boost conversion of power originating from a varying voltage source; additional conversion elements for also effecting conversion of power originating from the varying voltage source; and circuitry for selectively configuring the conversion elements with respect to delivery of power to a load to achieve greater conversion efficiency than if all of the power delivered to the load were constrained to flow through the additional conversion elements and at least some of the boost conversion elements. In another aspect power is converted from a voltage source having a predetermined source voltage range, and delivered to a load via two sets of power conversion elements, each set for effecting conversion of power from the voltage source, at least one of the sets having an input operating voltage range narrower than the source voltage range. The apparatus includes control circuitry for configuring and reconfiguring interconnections of the two sets with the voltage source and the load to provide an input operating voltage range for the apparatus which is greater than the input operating range of the set of power conversion elements having the narrower input operating voltage range. In another aspect, the input voltage operating range is enhanced for a power conversion circuit which has two sets of power conversion elements arranged to share power delivered to a load. The circuit is selectively configured with the two sets in series or not in series in a manner so that the input voltage operating range of the power conversion circuit is broader than the input voltage operating range of either of the sets of power conversion elements.

Claims

1. Apparatus for converting power from a varying voltage source and delivering it to a load, comprising

boost conversion elements for effecting a boost conversion of power originating from the varying voltage source,

additional conversion elements for also effecting conversion of power originating from the varying voltage source, and

a power factor correcting controller for causing variations in current drawn from the voltage source to follow variations in voltage of the voltage source.

2. The apparatus of claim 1 further comprising

circuitry for selectively configuring the conversion elements with respect to delivery of power to the load to achieve greater conversion efficiency than if all of the power delivered to the load were constrained to flow through the additional conversion elements and at least some of the boost conversion elements.

3. The apparatus of claim 2 wherein the circuitry selectively configures the conversion elements so that during some periods the power delivered to the load is constrained not to flow through the boost conversion elements.

4. The apparatus of claim 2 wherein the power is constrained not to flow through the boost conversion elements more than half of the time.

5. The apparatus of claim 2 wherein the circuitry selectively configures the conversion elements based on the voltage level of the varying voltage source.

6. The apparatus of claim 2 wherein the circuitry selectively configures the conversion elements based on when the voltage level of the varying voltage source falls within a specific range of values.

7. The apparatus of claim 2 wherein the circuitry selectively configures the conversion elements based on when the voltage level of the varying voltage source passes a threshold.

8. The apparatus of claim 7 wherein the threshold is based on a minimum input operating voltage of the additional conversion elements.

9. The apparatus of claim 1 wherein power converted by the boost conversion elements is delivered to the additional conversion elements for further conversion.

10. The apparatus of claim 9 wherein all of the power converted by the boost conversion elements is delivered to the additional conversion elements for further conversion.

11. The apparatus of claim 9 wherein power converted by the boost conversion elements is delivered to the additional conversion elements via a unidirectional element biased to permit current to pass only from the boost conversion elements toward the additional conversion elements.

12. The apparatus of claim 9 wherein power converted by the boost conversion elements is delivered via a short circuit path directly to the additional conversion elements.

13. The apparatus of claim 3 wherein during the periods when the power is constrained not to flow through the boost conversion elements, it is delivered from the voltage source to the additional conversion elements via a unidirectional component.

14. The apparatus of claim 1 wherein the voltage source is connected to the boost conversion elements via a switch which in one state disconnects the voltage source from the boost conversion elements.

15. The apparatus of claim 2 wherein the voltage source is connected to the boost conversion elements via a short circuit path.

16. The apparatus of claim 15 wherein the circuitry for selectively configuring the conversion elements comprises a switch controller for controlling the switch.

17. The apparatus of claim 1 wherein the additional conversion elements have a minimum input operating voltage and the boost conversion elements deliver power to the additional conversion elements at a voltage which is greater than the minimum input operating voltage of the additional conversion elements.

18. The apparatus of claim 1 wherein the additional conversion elements provide galvanic isolation between the source and the load.

19. The apparatus of claim 1 wherein the power factor correcting controller is associated with the additional conversion elements.

20. The apparatus of claim 1 wherein the power factor correcting controller regulates the voltage across the load to a predetermined value.

21. The apparatus of claim 1 wherein the voltage source comprises an AC source and further comprising a rectifier for rectifying the AC source.

22. The apparatus of claim 21 wherein the rectifier comprises a full wave rectifier.

23. The apparatus of claim 21 wherein the rectified power from the input power source is delivered via a short circuit path directly to the input of the boost conversion elements.

24. The apparatus of claim 17 wherein the voltage source comprises an AC source and further comprising a rectifier for rectifying the AC source.

25. The apparatus of claim 24 wherein the rectifier comprises a full wave rectifier.

26. The apparatus of claim 1 wherein the additional conversion elements comprise a pair of converters operating in a power sharing arrangement.

27. The apparatus of claim 26 further comprising reconfiguration control circuitry for connecting the pair of converters either in series or in parallel.

28. The apparatus of claim 26 wherein said power sharing arrangement comprises power sharing control circuitry.

29. The apparatus of claim 26 wherein the reconfiguration control circuitry connects the pair of converters in series when the voltage of the input source crosses a threshold.

30. The apparatus of claim 29 wherein the reconfiguration control circuitry connects the pair of converters in parallel when the voltage of the input source crosses a threshold.

31. The apparatus of claim 29 or 30 wherein the threshold is related to the maximum input operating voltage of either converter.

32. The apparatus of claim 26 wherein the converters share essentially equally in the power delivered to the load.

33. The apparatus of claim 26 wherein the converters comprise ZCS converters.

34. The apparatus of claim 33 wherein one of the ZCS converters comprises a booster and the other ZCS converter comprises a driver.

35. The apparatus of claim 33 wherein each of the converters of the pair has a positive input and a negative input, and further comprising a switch connecting the positive inputs of the two converters, a switch connecting the negative inputs of the two converters, and a diode connecting the positive input of one of the converters to the negative input of the other converter.

36. The apparatus of claim 1 wherein the additional conversion elements comprise more than two converters operating in a power sharing arrangement.

37. The apparatus of claim 26 further comprising output control circuitry for connecting the outputs of the pair of converters either in series or in parallel.

38. The apparatus of claim 37 wherein the output control circuitry connects the outputs of the pair of converters in series when the voltage at the input of the converters crosses a threshold.

39. The apparatus of claim 37 wherein the output control circuitry connects the outputs of the pair of converters in parallel when the voltage at the input of the converters crosses a threshold.

40. The apparatus of claim 38 or 39 wherein the threshold is related to the minimum input operating voltage of either converter.

41. The apparatus of claim 1 further comprising separate full wave rectifier circuits, the first rectifier circuit being interposed between the input source and the boost conversion elements, and the second rectifier circuit being interposed between the input source and the additional conversion elements.

42. The apparatus of claim 41 wherein the output of the second rectifier circuit is connected by a short circuit path to the input of the additional conversion elements.

43. The apparatus of claim 41 wherein the rectifier circuits comprise six unidirectional elements forming two bridges each having four of the unidirectional elements, two of the unidirectional elements belonging to both bridges, one of the bridges having its output connected to the boost conversion elements, the other having its output connected to the additional conversion elements.

44. A method for converting power from a varying voltage source and delivering it to a load, comprising causing

a boost conversion of power originating from the varying voltage source in boost conversion elements,

another conversion of power originating from the varying voltage source in additional conversion elements, and

power factor correcting the conversion of power.

45. The method of claim 44 wherein the conversions are caused selectively in a manner, with respect to delivery of power to the load, to achieve greater conversion efficiency than if all of the power delivered to the load were constrained to flow through the additional conversion elements and at least some of the boost conversion elements.

46. The method of claim 45 wherein the conversions are caused selectively to achieve a greater input voltage operating range for the apparatus than if all of the power delivered to the load were constrained to flow only through the additional conversion elements.

47. The method of claim 44 wherein the additional conversion is caused to occur in two converters.

48. The method of claim 47 further comprising selectively connecting the inputs of the two converters in parallel or series.

49. The method of claim 47 further comprising selectively connecting the outputs of the two converters in parallel or series.

50. Apparatus for converting power from a voltage source having a predetermined source voltage range, and delivering it to a load comprising

two sets of power conversion elements, each set for effecting conversion of power from the voltage source, at least one of the sets having an input operating voltage range narrower than the source voltage range, and

control circuitry for configuring and reconfiguring interconnections of the two sets with the voltage source and the load to provide an input operating voltage range for said apparatus which is greater than the input operating range of the set of power conversion elements having the narrower input operating voltage range.

51. The apparatus of claim 50 wherein the two sets operate in a power sharing arrangement.

52. The apparatus of claim 50 wherein the control circuitry connects the outputs of the two sets either in series or in parallel.

53. The apparatus of claim 50 wherein the control circuitry connects the outputs of the two sets in series when the voltage at the input of the two sets crosses a threshold.

54. The apparatus of claim 50 wherein the control circuitry connects the outputs of the two sets in parallel when the voltage at the input of the two sets crosses a threshold.

55. The apparatus of claim 53 or 54 wherein the threshold is related to the minimum input operating voltage of either of the sets.

56. The apparatus of claim 50 wherein the sets share essentially equally in the power delivered to the load.

57. The apparatus of claim 50 wherein the two sets comprise ZCS converters.

58. A method for enhancing the input voltage operating range of a power conversion circuit which has two sets of power conversion elements arranged to share power delivered to a load, comprising

configuring the circuit with the two sets selectively in series or in parallel so that the input voltage operating range of the power conversion circuit is broader than the input voltage operating range of either of the sets of power conversion elements.

59. The method of claim 58 wherein the two sets are configured in series by configuring their inputs in series.

60. The method of claim 58 wherein the two sets are configured in series by configuring their outputs in series.

61. The method of claim 58 wherein the two sets are configured in parallel by configuring their inputs in parallel.

62. The method of claim 58 wherein the two sets are configured in parallel by configuring their outputs in parallel.

63. An apparatus for converting power from a voltage source having a predetermined source voltage range, and delivering it to a load comprising

two sets of power conversion elements arranged to share power delivered to a load, each set having an input voltage operating range,

circuitry for selectively configuring the power conversion elements in series or in parallel so that an input voltage range of the configuration is greater than the input voltage operating range of either set of power conversion elements.

64. The apparatus of claim 63 wherein configuring the power conversion elements in series comprises connecting their inputs in series.

65. The apparatus of claim 63 wherein configuring the power conversion elements in series comprises connecting their inputs in parallel.

66. The apparatus of claim 63 wherein configuring the power conversion elements in parallel comprises connecting their inputs in parallel.

67. The apparatus of claim 63 wherein configuring the power conversion elements in parallel comprises connecting their outputs in parallel.