Fuel cell power system, method of distributing power, and method of operating a fuel cell power system

• US 6,497,974 B2
• Filed: 05/23/2001
• Issued: 12/24/2002
• Est. Priority Date: 05/23/2001
• Status: Expired due to Term

• Current Assignee: Emergent Power Inc. (Plug Power Inc.)
• Original Assignee: Avista Laboratories Inc. (Plug Power Inc.)
• Inventors: Fuglevand, William A.
• Primary Examiner(s): Ryan, Patrick
• Assistant Examiner(s): Crepeau, Jonathan
• Application Number:
  US09/864,526
• Publication Number:
  US 20020177018A1
• Time in Patent Office: 580 Days
• Field of Search: 429/13, 429/22, 429/23, 429/30, 320/166, 320/167
• US Class Current: 429/432
• 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 a D.C. voltage output while operating and which is electrically coupled to a load which has a variable voltage demand;

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

a circuit which, in operation, substantially simultaneously and selectively electrically couples and decouples the fuel call to the ultracapacitor based upon the voltage condition of the ultracapacitor, and further selectively electrically couples the ultracapacitor to the load when the voltage demand of the load exceeds the D.C. voltage output of the fuel cell.

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 voltage, and electrically de-couples the fuel cell from the ultracapacitor in response to the voltage of the ultracapacitor being greater than a second voltage.

3. A fuel cell power system in accordance with claim 2, and wherein the ultracapacitor has a maximum voltage rating, and 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, and wherein the battery is selectively electrically coupled to the load when the voltage demand of the load exceeds the D.C. voltage output of the fuel cell.

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 and which is selectively electrically coupled to a load having a variable voltage demand;

means defining a capacitance above one Farad selectively electrically coupled with the load;

electrochemical means for storing energy and which is selectively electrically coupled in parallel with the capacitance means and with the load; and

means for selectively electrically coupling and decoupling the means for electrochemically converting hydrogen to the capacitance means and to the electrochemical means for storing energy based upon the voltage condition of the capacitance means and the electrochemical means for storing energy, and further selectively electrically coupling the capacitance means and the electrochemical means for storing energy to the load when variable voltage demand of the load exceeds the D.C. voltage provided by the means for electrochemically converting hydrogen.

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

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 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 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 a D.C. voltage output while operating;

a capacitor, having a capacitance of at least one Farad, electrically coupled with a load having a variable voltage demand, and which further has a variable 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, and wherein the fuel cell supplies the D.C. voltage output to the load, and the circuit electrically couples the capacitor to the load when the D.C. voltage output of the fuel cell is less than the voltage demand of the load.

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

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.

28. A fuel cell power system comprising:

an ultracapacitor which is selectively electrically coupled to a load having a variable voltage demand and wherein the ultracapacitor 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 which is supplied to the load having a variable voltage demand;

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 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 voltage; and

wherein the ultracapacitor is electrically coupled to the load when the voltage demand of the load reaches a voltage value.

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 subsystems is within the operating voltage range of the ultracapacitor;

and wherein the voltage value is greater than the amount of D.C. current generated by the fuel cell.

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.

36. A fuel cell power system, comprising:

a plurality of fuel cells each of which produces a voltage output while operating, and which are each selectively electrically coupled to a load having a variable voltage demand;

an ultracapacitor which has a maximum and a minimum voltage charge condition, and wherein the plurality of fuel cells are selectively electrically coupled and decoupled to the ultracapacitor to substantially maintain the ultracapacitor in a voltage charge condition between the maximum and minimum voltage charge conditions;

switching circuitry electrically coupled to the respective fuel cells, and with the ultracapacitor, and wherein the switching circuitry selectively permits, (1) the respective fuel cells to be selectively electrically coupled and decoupled to the ultracapacitor, and (2) the respective fuel cells and the ultracapacitor to be selectively electrically coupled and decoupled to the load; and

a controller disposed in sensing relation relative to (1) the voltage output of the respective fuel cells, (2) the voltage charge condition of the ultracapacitor, and (3) the voltage demand of the load, and wherein the controller is controllably electrically coupled to the switching circuitry, and in response to the voltage demand of the load to selectively electrically couple the respective fuel cells in various combinations to the ultracapacitor when the ultracapacitor has a minimum voltage charge condition, and to electrically decouple the respective fuel cells from the ultracapacitor when the ultracapacitor has a maximum voltage charge condition, and to further selectively electrically couple and decouple the respective fuel cells and the ultracapacitor, when the ultracapacitor is in the maximum charged condition, in various combinations with the load, such that the additive combination of the electrical power delivered by the respective fuel cells, and the ultracapacitor, to the load substantially meets the voltage demand of the load.

37. A fuel cell power system, comprising:

a fuel cell which has an electrical power output when operational, and which is electrically coupled to a load which has a variable voltage demand;

a plurality of ultracapacitors each of which has a maximum charge condition;

switching circuitry which selectively electrically couples and decouples the respective ultracapacitors to the load and to the fuel cell; and

a controller disposed in controlling relation relative to the switching circuitry and in sensing relation relative to, (1) the electrical power output of the fuel cell, (2) the voltage demand of the load, and (3) the charge condition of the respective ultracapacitors, and wherein in a first operational condition, when the voltage demand of the load exceeds the power output of the fuel cell, the controller causes the switching circuitry to selectively couple individual ultracapacitors having a maximum charged condition to the load to provide electrical power which, when additively combined with the electrical power output of the fuel cell, meets the voltage demand of the load, and in a second condition, to selectively electrically couple and decouple the electrical power output of the fuel cell to the respective ultracapacitors to maintain the individual ultracapacitors in the maximum charged condition, and wherein the first and second operational conditions are performed substantially simultaneously.

38. A fuel cell power system, comprising:

a plurality of fuel cells each of which produces a voltage output while operating, and which are each selectively electrically coupled to a load having a voltage demand which varies between an abrupt, short term, increased voltage demand, to a longer term increased voltage demand;

a plurality of ultracapacitors, each of which has a maximum and minimum voltage charge condition, and wherein the plurality of fuel cells are selectively electrically coupled in various combinations to the individual ultracapacitors to substantially maintain the plurality of ultracapacitors in a voltage charge condition between the minimum and maximum charge conditions;

a battery which has a minimum and maximum voltage charge condition, and wherein the plurality of fuel cells are selectively electrically coupled in various combinations to the battery to substantially maintain the battery between the minimum and maximum voltage charge conditions;

switching circuitry electrically coupled to each of the respective fuel cells, the individual ultracapacitors and the battery, and wherein the switching circuitry selectively permits, (1) the respective fuel cells to be selectively electrically coupled to the respective ultracapacitors, and the battery, and (2) the respective fuel cells, individual ultracapacitors, and the battery to be selectively electrically coupled and decoupled to the load; and

a controller disposed in sensing relation relative to (1) the voltage output of the respective fuel cells, (2) the voltage charge condition of the respective ultracapacitors, (3) the voltage charge condition of the battery; and

(4) the variable voltage demand of the load, and wherein the controller is electrically controllably coupled to the switching circuitry, and in response to a first operational condition, when the variable voltage demand is abrupt, and short term, and further exceeds the power output of the individual fuel cells, the controller causes the switching circuitry to selectively electrically couple individual ultracapacitors having a charge condition between the maximum and minimum charge condition to the load to provide electrical power which, when additively combined with the electrical power output of the individual fuel cells which are electrically coupled to the load, meets the abrupt, and short term, voltage demand of the load, and wherein the controller, in a second operational condition, when the variable voltage demand is longer term, and further exceeds the power output of the individual fuel cells which are electrically coupled to the load, causes the switching circuitry to selectively electrically couple combinations of individual ultracapacitors, and the battery, each of which has a charge condition between the maximum and minimum charge conditions, to the load to provide electrical power which, when additively combined with the power output of the individual fuel cells which are electrically coupled to the load, meets the longer term voltage demand of the load, and wherein in a third operational condition, when the individual ultracapacitors and/or the battery individually have a voltage condition less that the maximum charged condition, the controller causes the switching circuitry to selectively electrically couple and decouple the individual fuel cells, in various combinations to the respective ultracapacitors and/or battery to substantially maintain the voltage condition of each between the maximum and minimum voltage conditions, and wherein the first, second and third operational conditions are performed substantially at the same time.