Bidirectional power conversion with multiple control loops

• US 6,894,461 B1
• Filed: 10/11/2002
• Issued: 05/17/2005
• Est. Priority Date: 10/11/2002
• Status: Active Grant

• Current Assignee: Analog Devices International Unlimited Company (Analog Devices, Inc.)
• Original Assignee: Linear Technology Corporation (Analog Devices, Inc.)
• Inventors: Hack, Thomas P., Dobkin, Robert C.
• Primary Examiner(s): HAN, YOUNGHUIE JESSICA
• Application Number:
  US10/270,799
• Time in Patent Office: 949 Days
• Field of Search: 323/205, 323/206, 323/208, 307/82
• US Class Current: 323/205
• CPC Class Codes: G05F 1/70 Regulating power factor; Regulating reactive current or power
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence
• CPC Class Codes: H02M 3/33584 Bidirectional converters

Abstract

Bidirectional power conversion systems provide the ability to change power attributes to and from a component. Current bidirectional power conversion systems use a unidirectional power converter for each direction. The integration of the two normally independent power converters results in a bidirectional power converter with nearly half the size, weight, volume, cost and complexity. Described are embodiments of bidirectional power conversion systems that allow power transfer between two or more components without requiring the use of separate unidirectional power converters.

Claims

1. A bidirectional power converter that controls the magnitude and direction of power flow between a plurality of power buses, said bidirectional power converter that comprises:

at least one reactive element that is coupled to said power buses; and

at least one of said power buses that is capable of both supplying power to said reactive element and receiving power from said reactive element; and

a control circuit that is adapted to regulate the transfer of power from said at least one power bus to said reactive element and from said reactive element to said at least one power bus, wherein the reactive element is an inductor and said control circuit comprises;

a ground switch that intermittently couples said reactive element to ground;

at least one power switch that intermittently couples at least one of said power buses to said reactive element; and

a driver circuit that is coupled to said ground switch and said power switch, said driver circuit that provides at least two driver signals, said driver signals that control whether each said ground switch and said power switch is OPEN or CLOSED.

2. The converter of claim 1 wherein said ground switch and said power switch are power metal-oxide semiconductor field effect transistors.

3. The converter of claim 1 wherein said control circuit further comprises:

at least one diode, said diode that is coupled between said reactive element and one of said power buses; and

at least one direction comparator that produces a selection signal, said selection signal that is provided to said driver circuit, said selection signal that is indicative of the voltage drop across said diode.

4. The converter of claim 1 wherein said control circuit further comprises at least one direction comparator that produces a selection signal, said selection signal that is provided to said driver circuit, said selection signal that is indicative of the available power from one of said power buses.

5. The converter of claim 1 wherein said converter comprises one sense resistor, said reactive element that receives power from only one of said power buses as a time, said reactive element that supplies power to only one of said power buses at a time.

6. The converter of claim 1 wherein said control circuit further comprises:

at least one sense resistor, said sense resistor that is coupled between said inductor and one of said power buses; and

a zero-current comparator, said zero-current comparator that measures the voltage across said sense resistor, said zero-current comparator that provides a rectifier signal to said driver circuit, said rectifier signal that is indicative of the current being supplied to said power bus.

7. The converter of claim 1 wherein said control circuit further comprises:

at least one sense resistor, said sense resistor coupled between said inductor and one of said power buses; and

a current amplifier that measures the voltage across said sense resistor, said current amplifier that produces a current amplifier output signal

indicative of the current being supplied to said power bus.

8. The converter of claim 7 wherein said control circuit further comprises:

an error amplifier circuit that receives a sense signal, said sense signal being supplied through an input circuit, said error amplifier circuit comprising a feedback network, said error amplifier circuit that produces an error signal indicative of said sense signal;

a pulse-width modulation comparator that receives said current amplifier output signal and said error signal, said pulse-width modulation comparator that produces a latch signal based on said current amplifier output signal and said error signal; and

a pulse-width modulation latch that receives said latch signal, said pulse-width modulation latch that provides a charge signal indicative of said latch signal to said driver circuit.

9. The converter of claim 8 wherein said sense signal, said input circuit and said feedback network are each selected based on a selection signal.

10. The converter of claim 9 wherein said sense signal is provided through a resistive network voltage divider, said sense signal that is indicative of the power that is being transferred to at least one of said power buses.

11. The converter of claim 9 wherein said sense signal is said current amplifier output signal.

12. The converter of claim 9 wherein said input circuit comprises a resistive network voltage divider that is coupled to one of said power buses.

13. The converter of claim 9 wherein said feedback network comprises a capacitor.

14. The converter of claim 9 wherein said feedback network comprises a capacitor in series with a resistor.

15. A bidirectional power converter that controls the magnitude and direction of power flow between a plurality of power buses, said bidirectional power converter that comprises:

at least one reactive element that is coupled to said power buses; and

at least one of said power buses that is capable of both supplying power to said reactive element and receiving power from said reactive element; and

a control circuit that is adapted to regulate the transfer of power from said at least one power bus to said reactive element and from said reactive element to said at least one power bus, wherein said control circuit further comprises an adaptive slope compensation circuit, said adaptive slope compensation circuit that maintains the stability of said converter when a duty cycle of said converter is above a preset value.

16. The adaptive compensation circuit of claim 15 wherein said preset value is between about 1% and about 50%.

17. A method for bidirectionally transferring power between a plurality of power buses, said method comprising:

coupling at least one reactive element to said power buses;

in a first configuration of the circuit, supplying power from at least one of said power buses to said reactive element;

in a second configuration of the circuit, providing power to said at least one power bus from said reactive element;

monitoring the direction and magnitude of current flowing through at least one of said at least one reactive element; and

regulating the transfer of power from said at least one power bus to said reactive element and from said reactive element to said at least one power bus.

18. A method for bidirectionally transferring power between a plurality of power buses, said method comprising:

coupling at least one reactive element to said power buses;

in a first configuration, supplying power from at least one of said power buses to said reactive element;

in a second configuration, providing power to said at least one power bus from said reactive element;

regulating the transfer of power from said at least one power bus to said reactive element and from said reactive element to said at least one power bus, wherein said supplying comprises sensing the available power in at least one of said power buses.

19. A method for bidirectionally transferring power between a plurality of power buses, said method comprising:

coupling at least one reactive element to said power buses;

in a first configuration, supplying power from at least one of said power buses to said reactive element;

in a second configuration, providing power to said at least one power bus from said reactive element;

regulating the transfer of power from said at least one power bus to said reactive element and from said reactive element to said at least one power bus, wherein said regulating comprises;

producing at least one sense signal that is indicative of the current being supplied to at least one of said power buses;

providing an error signal that is indicative of said sense signal;

controlling a driver circuit that produces at least one control signal based on said error signal; and

switching at least one switch that is connected to at least one of said power buses intermittently based on said control signal.

20. A bidirectional power converter that controls the magnitude and direction of power flow between a plurality of power buses, said bidirectional power converter that comprises:

at least one reactive element that is coupled to said power buses; and

at least one of said power buses that is capable of both supplying power to said reactive element and receiving power from said reactive element; and

a control circuit that is adapted to regulate the transfer of power from said at least one power bus to said reactive element and from said reactive element to said at least one power bus, wherein said reactive element is a flyback transformer.

21. The converter of claim 20 wherein said flyback transformer comprises at least one primary winding and at least one secondary winding.

22. The converter of claim 21 wherein said control circuit comprises:

at least a first switch that intermittently couples said primary winding to a first sense resistor;

at least a second switch that intermittently couples said secondary winding to a second sense resistor; and

a driver circuit that is coupled to said first and second switches, said driver circuit that provides at least two driver signals, said driver signals that control whether each said first switch and said second switch is OPEN or CLOSED.

23. The converter of claim 21 wherein said control circuit comprises:

at least a first switch that intermittently couples said primary winding to a sense resistor;

at least a second switch that intermittently couples said secondary winding to said sense resistor; and

a driver circuit that is coupled to said first and second switches, said driver circuit that provides at least two driver signals, said driver signals that control whether each said first switch and said second switch is OPEN or CLOSED.

24. The converter of claim 23 wherein said first and second switches are power metal-oxide semiconductor field effect transistors.

25. The converter of claim 24 wherein a diode is coupled between the drain terminal and the source terminal of said first power metal-oxide semiconductor field effect transistor.

26. The converter of claim 24 wherein a diode is coupled between the drain terminal and the source terminal of said second power metal-oxide semiconductor field effect transistor.

27. The converter of claim 23 wherein said control circuit further comprises:

at least one diode, said diode that is coupled between said reactive element and one of said power buses; and

at least one direction comparator that produces a selection signal, said selection signal that is provided to said driver circuit, said selection signal that is indicative of the voltage drop across said diode.

28. The converter of claim 23 wherein said control circuit further comprises at least one direction comparator that produces a selection signal, said selection signal that is provided to said driver circuit, said selection signal that is indicative of the available power from one of said power buses.

29. The converter of claim 23 wherein said control circuit further comprises a zero-current comparator that measures the voltage across said sense resistor, said zero-current comparator that provides a rectifier signal to said driver circuit indicative of the current being supplied to said power bus.

30. The converter of claim 23 wherein said control circuit further comprises a current amplifier that measures the voltage across said sense resistor, said current amplifier that produces a current amplifier output signal that is indicative of the current being supplied to said power bus.

31. The converter of claim 30 wherein said control circuit further comprises:

an error amplifier circuit that receives a sense signal, said sense signal being supplied through an input circuit, said error amplifier circuit comprising a feedback network, said error amplifier circuit that provides an error signal indicative of said sense signal;

a pulse-width modulation comparator, said pulse-width modulation comparator that receives said current amplifier output signal from said current amplifier, said pulse-width modulation comparator that receives said error signal from said error amplifier, said pulse-width modulation comparator that provides a latch signal based on said current amplifier output signal and said error signal; and

a pulse-width modulation latch, said pulse-width modulation latch that receives said latch signal, said pulse-width modulation latch that provides a charge signal indicative of said latch signal to said driver circuit.

32. The converter of claim 31 wherein said sense signal, said input circuit and said feedback network are each selected based on a selection signal.

33. The converter of claim 32 wherein said sense signal is provided through a resistive network voltage divider, said sense signal that is indicative of the power that is transferred to at least one of said power buses.

34. The converter of claim 32 wherein said sense signal is provided by said current amplifier output signal.

35. The converter of claim 32 wherein said input circuit comprises a resistive network voltage divider coupled to one of said power buses.

36. The converter of claim 32 wherein said feedback network comprises a capacitor.

37. The converter of claim 32 wherein said feedback network comprises a capacitor in series with a resistor.

38. A bidirectional power converter that controls the magnitude and direction of power flow between a plurality of power buses, said bidirectional power converter that comprises:

at least one reactive element that is coupled to said power buses; and

at least one of said power buses that is capable of both supplying power to said reactive element and receiving power from said reactive element; and

a control circuit that is adapted to regulate the transfer of power from said at least one power bus to said reactive element and from said reactive element to said at least one power bus, wherein said control circuit is operable to monitor the direction and magnitude of current flowing through at least one of said at least one reactive element.

39. The converter of claim 38 wherein said reactive element is an inductor.

40. The converter of claim 39 wherein:

at least one of said plurality of power buses is coupled to a first side of said inductor;

at least one of said plurality of power buses is coupled to a second side of said inductor.

41. The converter of claim 38, further comprising an adaptive slope compensation circuit, wherein said adaptive slope compensation circuit is operable to maintain the stability of said converter when a duty cycle of said converter is above a preset value.

42. The converter of claim 38, further comprising:

a ground switch that is operable to intermittently couple said reactive element to ground;

at least one power switch that is operable to intermittently couple at least one of said power buses to said reactive element; and

a driver circuit that is coupled to said ground switch and said power switch, said driver circuit operable to provide at least two driver signals, said driver signals controlling whether each said ground switch and said power switch is OPEN or CLOSED.

43. The converter of claim 42 wherein said ground switch and said power switch are power metal-oxide semiconductor field effect transistors.

44. The converter of claim 42 wherein said control circuit further comprises:

at least one diode that is coupled between said reactive element and one of said power buses; and

at least one direction comparator operable to produce a selection signal that is indicative of the voltage drop across said diode.

45. The converter of claim 42 wherein said control circuit further comprises at least one direction comparator that is operable to produce a selection signal to said driver circuit that is indicative of the available power from one of said power buses.

46. The converter of claim 42 wherein said control circuit further comprises:

at least one sense resistor, said sense resistor coupled between said inductor and one of said power buses; and

a current amplifier that is operable to measure the voltage across said sense resistor.

47. The converter of claim 46, wherein said current amplifier is operable to produce a current amplifier output signal indicative of the current being supplied to said power bus.

48. The converter of claim 38, wherein said control circuit further comprises:

at least one sense resistor, said sense resistor that is coupled between at least one of said reactive elements and one of said power buses.

49. The converter of claim 38 wherein said reactive element is a flyback transformer.