FUEL CELL POWER SYSTEM, METHOD OF DISTRIBUTING POWER, AND METHOD OF OPERATING A FUEL CELL POWER SYSTEM

• US 20020177018A1
• Filed: 05/23/2001
• Published: 11/28/2002
• Est. Priority Date: 05/23/2001
• Status: Active Grant

• Current Assignee: Emergent Power Inc. (Plug Power Inc.)
• Original Assignee: Avista Laboratories Inc. (Plug Power Inc.)
• Inventors: Fuglevand, William A.
• Granted Patent: US 6,497,974 B2
• Time in Patent Office: Days
• US Class Current: 429/22
• CPC Class Codes: H01M 16/003 of fuel cells with other electrochemical devices, e.g. capacitors, electrolysers
• CPC Class Codes: H01M 8/04298 Processes for controlling fuel cells or fuel cell systems
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04567 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04589 of fuel cell stacks
• CPC Class Codes: H01M 8/04679 of fuel cell stacks
• CPC Class Codes: H01M 8/0488 of fuel cell stacks
• CPC Class Codes: H01M 8/0491 of fuel cell stacks
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H02J 2300/30 The power source being a fuel cell
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A fuel cell power system, comprising a fuel cell which generates D.C. voltage while operating; an ultracapacitor which, in operation, is electrically coupled with a load and has a voltage condition; and a circuit which, in operation, electrically couples and decouples the fuel cell to the ultracapacitor based upon the voltage condition of the ultracapacitor.

Claims

1. A fuel cell power system, comprising:

a fuel cell which generates D.C. voltage while operating;

an ultracapacitor which, in operation, is electrically coupled with a load and has a voltage condition; and

a circuit which, in operation, electrically couples and decouples the fuel cell to the ultracapacitor based upon the voltage condition of the ultracapacitor.

2. A fuel cell power system as claimed in claim 1, wherein the ultracapacitor, in operation, is charged and discharged to different voltages, and wherein the circuit electrically couples the fuel cell to the ultracapacitor in response to the voltage of the ultracapacitor being less than a first predetermined voltage, and electrically de-couples the fuel cell from the ultracapacitor in response to the voltage of the ultracapacitor being greater than a second predetermined voltage.

3. A fuel cell power system in accordance with claim 2, wherein the ultracapacitor has a maximum voltage rating, wherein the fuel cell is defined by a number of fuel cell subsystems coupled together in series, and wherein the combined voltage of the numbered fuel cell subsystems is not greater than the maximum voltage rating of the ultracapacitor.

4. A fuel cell power system in accordance with claim 3, and further comprising:

a battery coupled in parallel with the ultracapacitor, and which has a maximum voltage, and wherein the combined voltage of the numbered fuel cell subsystems is not greater than the maximum voltage of the battery.

5. A fuel cell power system in accordance with claim 4 wherein the battery is a single cell battery.

6. A fuel cell power system in accordance with claim 1, wherein the ultracapacitor has an operating voltage range, and wherein the fuel cell is defined by a plurality of fuel cell subsystems coupled together in series and which produce a voltage within the operating range of the ultracapacitor.

7. A fuel cell power system in accordance with claim 4, wherein the circuit is configured to operate the ultracapacitor in an operating voltage of about 1.8 to about 2.2 Volts DC, and wherein the fuel cell is defined by a plurality of fuel cell subsystems coupled together in series, each of which produces a voltage of about 0.6 Volts.

8. A fuel cell power system in accordance with claim 1, wherein the fuel cell is defined by a plurality of fuel cell subsystems, and wherein each fuel cell subsystem comprises an ion exchange membrane.

9. A fuel cell power system in accordance with claim 6, and further comprising:

a second plurality of fuel cell subsystems, coupled together in series, and which is in parallel with the first mentioned plurality of fuel cell subsystems.

10. A fuel cell power system, comprising:

means for electrochemically converting hydrogen to D.C. voltage;

means defining a capacitance above one Farad selectively electrically coupled with a load and which has a voltage condition;

electrochemical means for storing energy coupled in parallel with the capacitance means; and

means for selectively electrically coupling and decoupling the means for electrochemically converting hydrogen to the capacitance means based upon the voltage condition of the capacitance means.

11. A fuel cell power system in accordance with claim 10, wherein the means for electrochemically converting hydrogen comprises a fuel cell of a type selected from the group consisting of proton exchange membrane, solid oxide, phosphoric acid, alkaline, and molten carbon.

12. A fuel cell power system as claimed in claim 10, wherein the capacitance means, in operation, is charged and discharged to different voltages by the means for electrochemically converting hydrogen, and wherein the coupling and decoupling means electrically couples the means for electrochemically converting hydrogen to the capacitance means in response to the voltage of the capacitance means being less than a first predetermined voltage, and electrically de-couples the means for electrochemically converting hydrogen from the capacitance means in response to the voltage of the capacitance means being greater than a second predetermined voltage.

13. A fuel cell power system in accordance with claim 12, wherein the capacitance means has a maximum voltage rating, wherein the means for electrochemically converting hydrogen is defined by a number of fuel cell subsystems coupled together in series, and wherein the combined voltage of the numbered fuel cell subsystems is not greater than the maximum voltage rating of the capacitance means.

14. A fuel cell power system in accordance with claim 13, wherein the electrochemical means has a maximum voltage, and wherein the combined voltage of the numbered fuel cell subsystems is not greater than the maximum voltage of the electrochemical means.

15. A fuel cell power system in accordance with claim 10, wherein the electrochemical means comprises a single cell battery.

16. A fuel cell power system in accordance with claim 10, wherein the capacitance means has an operating voltage range, and wherein the means for electrochemically converting hydrogen is defined by a plurality of fuel cell subsystems coupled together in series and which produce a voltage within the operating range of the capacitance means.

17. A fuel cell power system in accordance with claim 10, wherein the coupling and decoupling means is configured to operate the capacitance means in an operating voltage of about 1.8 to about 2.2 Volts DC, and wherein the means for electrochemically converting hydrogen is defined by a plurality of fuel cell subsystems coupled together in series, each of which produces a voltage of about 0.6 Volts.

18. A fuel cell power system in accordance with claim 10, wherein the means for electrochemically converting hydrogen is defined by a plurality of fuel cell subsystems, and wherein each fuel cell subsystem comprises means for ion exchange.

19. A fuel cell power system in accordance with claim 16, and further comprising:

a second plurality of fuel cell subsystems, coupled together in series, and which is in parallel with the first mentioned plurality of fuel cell subsystems.

20. A fuel cell power system, comprising:

a fuel cell which generates D.C. voltage while operating;

a capacitor, having a capacitance of at least one Farad, electrically coupled with a load and which has a voltage condition; and

a circuit which selectively electrically couples and decouples the fuel cell to the capacitor based upon the voltage condition of the capacitor.

21. A fuel cell power system as claimed in claim 20, wherever the capacitor, in operation, is charged and discharged to different voltages, and wherever the circuit electrically couples the fuel cell to the capacitor in response to the voltage of the capacitor being less than a first predetermined voltage, and electrically de-couples the fuel cell from the capacitor in response to the voltage of the capacitor being greater than a second predetermined voltage.

22. A fuel cell power system in accordance with claim 21, wherein the capacitor has a maximum voltage rating, wherein the fuel cell is defined by a number of fuel cell subsystems coupled together in series, and wherein the combined voltage of the numbered fuel cell subsystems is not greater than the maximum voltage rating of the capacitor.

23. A fuel cell power system in accordance with claim 22, and further comprising:

a single cell battery coupled in parallel with the capacitor, and which has a maximum voltage, and wherein the combined voltage of the numbered fuel cell subsystems is not greater than the maximum voltage of the battery.

24. A fuel cell power system in accordance with claim 20, wherein the capacitor has an operating voltage range, and wherein the fuel cell is defined by a plurality of fuel cell subsystems coupled together in series and which produce a voltage within the operating range of the capacitor.

25. A fuel cell power system in accordance with claim 20, wherein the capacitor has an operating voltage of about 1.8 to about 2.2 Volts DC, and wherein the fuel cell is defined by a plurality of fuel cell subsystems coupled together in series, each of which produces a voltage of about 0.6 Volts.

26. A fuel cell power system in accordance with claim 20, wherein the fuel cell is defined by a plurality of fuel cell subsystems, and wherein each fuel cell subsystem comprises an ion exchange membrane.

27. A fuel cell power system in accordance with claim 24, and further comprising:

a second plurality of fuel cell subsystems, coupled together in series, and which is in parallel with the first mentioned plurality of fuel cell subsystems.

29. A fuel cell power system in accordance with claim 28, and further comprising a battery electrically coupled in parallel with the ultracapacitor, and wherein the battery has a maximum voltage, and the ultracapacitor has an operating voltage range, and wherein the cumulative voltage of the plurality of fuel cell subsystems coupled together is within the operating voltage range of the ultracapacitor, and less than the maximum voltage of the battery.

30. A fuel cell power system in accordance with claim 28, wherein the fuel cell subsystems each produce about the same voltage.

31. A fuel cell power system in accordance with claim 28, wherein the ultracapacitor has an operating voltage range, and wherein the cumulative power provided by the plurality of fuel cell subsystem is within the operating voltage range of the ultracapacitor.

32. A fuel cell power system in accordance with claim 28, and further comprising;

a second plurality of fuel cell subsystems, which are coupled together in series, and wherein the second plurality of fuel cell subsystem is in parallel with the first plurality of fuel cell subsystems.

33. A fuel cell power system in accordance with claim 29, wherein the control circuitry is configured to operate the ultracapacitor in an operating voltage of about 1.8 to about 2.2 Volts DC, and wherein the fuel cell is defined by a plurality of fuel cell subsystems coupled together in series, and which each produce a voltage of about 0.6 Volts.

34. A fuel cell power system in accordance with claim 28, wherein each fuel cell subsystem comprises an ion exchange membrane.

35. A fuel cell power system as claimed in claim 28, wherein the control circuitry comprises an embedded controller.

37. A method of operating a fuel cell power system in accordance with claim 36 wherein electrically coupling and decoupling the fuel cell to the ultracapacitor comprises electrically coupling the fuel cell to the ultracapacitor when the voltage of the ultracapacitor is less than a first predetermined voltage, and electrically decoupling the fuel cell from the ultracapacitor when the voltage of the ultracapacitor is greater than a second predetermined voltage

38. A method in accordance with claim 36, and further comprising electrically coupling a battery in parallel with the ultracapacitor.

39. A method in accordance with claim 36, and further comprising electrically coupling a plurality of fuel cell subsystems together in series to define the fuel cell.

40. A method in accordance with claim 36, and further comprising electrically coupling a battery, which has a maximum voltage, in parallel with the ultracapacitor, and wherein the fuel cell subsystems which are electrically coupled in series produce a voltage less than the maximum voltage of the battery.

41. A method in accordance with claim 40, wherein the battery is a single cell battery.

42. A method in accordance with claim 40, wherein the ultracapacitor has an operating voltage range, and wherein the fuel cell subsystems which are electrically coupled together in series produce a voltage which lies within the operating voltage range of the ultracapacitor.

43. A method in accordance with claim 36 and further comprising electrically coupling a load across the ultracapacitor.

44. A method in accordance with claim 36, wherein, in operation, the ultracapacitor operates in an operating voltage of about 1.8 to about 2.2 Volts DC, and wherein the method further comprises:

defining the fuel cell by utilizing a plurality of fuel cell subsystems which are electrically coupled together in series, and which each produces a voltage of about 0.6 Volts.

46. A method in accordance with claim 45 wherein coupling and decoupling the fuel cell to the capacitor comprises electrically coupling the fuel cell to the capacitor when the voltage of the capacitor is less than a first predetermined voltage, and electrically decoupling the fuel cell from the capacitor when the voltage of the capacitor is greater than a second predetermined voltage.

47. A method in accordance with claim 45, and further comprising electrically coupling a battery in parallel with the capacitor.

48. A method in accordance with claim 45, and further comprising electrically coupling a plurality of fuel cell subsystems together in series to define the fuel cell.

49. A method in accordance with claim 45, and further comprising electrically coupling a single cell battery, which has a maximum voltage, in parallel with the capacitor, and wherein the fuel cell subsystems which are electrically coupled in series produce a voltage less than the maximum voltage of the battery.

50. A method in accordance with claim 49, wherein the capacitor has an operating voltage range, and wherein the fuel cell subsystems which are electrically coupled together in series produce a voltage which lies within the operating voltage range of the capacitor.

51. A method in accordance with claim 50 and further comprising electrically coupling a load across the capacitor.

52. A method in accordance with claim 45, wherein the capacitor has an operating voltage of about 1.8 to about 2.2 Volts DC, and wherein the method further comprises:

defining the fuel cell by utilizing a plurality of fuel cell subsystems which are electrically coupled together in series, and which each produces a voltage of about 0.6 Volts.

28. A fuel cell power system comprising:

an ultracapacitor electrically coupled to a load and which is charged and discharged to different voltages;

a plurality of fuel cell subsystems electrically coupled together in series, and which produce direct current electrical energy;

a switch electrically coupled with the plurality of fuel cell subsystems to selectively electrically couple the plurality of fuel cell subsystems to the ultracapacitor; and

control circuitry which causes the switch to electrically couple the fuel cell to the ultracapacitor in response to the voltage of the ultracapacitor being less than a first predetermined voltage, and to electrically de-couple the fuel cell from the ultracapacitor in response to the voltage of the ultracapacitor being greater than a second predetermined voltage.

36. A method of operating a fuel cell power system, comprising:

providing an ultracapacitor which, in operation, has a voltage condition;

providing a fuel cell which produces direct current electrical energy; and

electrically coupling and decoupling the fuel cell to the ultracapacitor based on the voltage condition of the ultracapacitor.

45. A method of operating a fuel cell power system, comprising:

providing an capacitor, having a capacitance greater than one Farad, which is electrically coupled to a load, in operation and which is charged and discharged to different voltages, in operation;

providing a fuel cell which produces direct current electrical energy in operation; and

electrically coupling and decoupling the fuel cell to the capacitor depending on the voltage of the capacitor.

53. A method of distributing electrical power, which is generated by a fuel cell power system, to a load, the method comprising:

electrically coupling an ultracapacitor to the load, which, in operation, is charged and discharged to different voltages;

electrically coupling a plurality of fuel cell subsystems together in series;

providing a switch which is electrically coupled to both the plurality of fuel cell subsystems and the ultracapacitor; and

selectively controlling the switch to electrically couple the fuel cell subsystems to the ultracapacitor when the voltage of the ultracapacitor is less than a first predetermined voltage, and to electrically de-couple the fuel cell subsystem from the ultracapacitor when the voltage of the ultracapacitor is greater than a second predetermined voltage.

54. A method in accordance with claim 53, wherein the fuel cell subsystems each produce about the same voltage.

55. A method in accordance with claim 53, wherein selectively controlling the switch comprises using a processor to selectively control same.

56. A method in accordance with claim 53, wherein the ultracapacitor has a maximum voltage, and the method further comprises defining the fuel cell by a plurality of fuel cell subsystems electrically coupled together in series and which together in series produce a voltage less than the maximum voltage of the ultracapacitor.

57. A method in accordance with claim 53, wherein, in operation, the ultracapacitor operates in a voltage range of about 1.8 to about 2.2 Volts DC.

58. A method in accordance with claim 53, wherein the ultracapacitor has an operating voltage of about 1.8 to about 2.2 Volts DC, and a maximum voltage which is greater than about 2.2 Volts DC, and wherein the method further comprises electrically coupling a plurality of fuel cell subsystems together in series to define the fuel cell, and wherein each fuel cell subsystem produces a voltage of less than about 0.6 Volts.

59. A method in accordance with claim 53, and further comprising defining the fuel cell by utilizing a plurality of fuel cell subsystems, and wherein each fuel cell subsystem comprises an ion exchange membrane.

60. A method in accordance with claim 53, and further comprising electrically coupling a battery in parallel with the ultracapacitor, and wherein the battery is a single cell battery having a voltage of about 2 Volts DC.