Granted Patent B2

US 7,326,480 · App. 10/830,929 · Granted Feb 5, 2008

Abstract

Claims (41)

1. A fuel cell power system comprising:

a fuel cell which has an optimal voltage;

an energy storage device having a nominal voltage substantially similar to the optimal voltage of the fuel cell; and

an electrical switch that, in operation, selectively electrically couples the fuel cell to the energy storage device to charge the energy storage device.

2. A fuel cell power system as claimed in claim 1 , and further comprising a plurality of additional fuel cells respectively having optimal voltages substantially similar to the optimal voltage of the first mentioned fuel cell.

3. A fuel cell power system as claimed in claim 1 , wherein the fuel cell comprises multiple fuel cell subracks which selectively support respective fuel cell modules, and wherein the respective fuel cell modules can be operatively removed from the individual subracks while the subracks remain operational.

4. A fuel cell power system as claimed in claim 1 , wherein the electrical switch selectively electrically couples the fuel cell to the electrical charge storage device without any intermediate power conditioning or power conversion.

5. A fuel cell power system comprising:

a plurality of fuel cells, the fuel cells respectively having substantially similar nominal voltages;

an energy storage device having a nominal voltage substantially similar to that of each of the fuel cells; and

electrical switching circuitry electrically coupled to the fuel cells and the energy storage device, and wherein the electrical switching circuitry is configured to electrically couple a selectable number of the fuel cells to the charge storage device to maintain the voltage of the charge storage device above a predetermined voltage.

6. A fuel cell power system as claimed in claim 5 , wherein the fuel cells are defined by fuel cell stacks.

7. A fuel cell power system as claimed in claim 5 , wherein the fuel cells are independently operable.

8. A fuel cell power system as claimed in claim 5 , wherein the fuel cells are constructed and arranged so as to be able to be removed and replaced while the fuel cell power system is in operation.

9. A fuel cell power system comprising:

a fuel cell which has a nominal operating voltage;

an energy storage device having a nominal voltage substantially similar to the nominal operating voltage of the fuel cell;

an electrical switch selectively coupling the fuel cell to the energy storage device; and

a controller coupled in voltage sensing relation relative to the fuel cell and the energy storage device, and further coupled in controlling relation relative to the electrical switch, the controller selectively controlling the switch to selectively electrically couple the fuel cell to the energy storage device to maintain the voltage of the energy storage device above a predetermined threshold.

10. A fuel cell power system as claimed in claim 9 , wherein the energy storage device comprises a plurality of batteries.

11. A fuel cell power system as claimed in claim 9 , wherein the energy storage device comprises a capacitor.

12. A fuel cell power system as claimed in claim 9 , wherein the energy storage device comprises a battery and a capacitor.

13. A fuel cell power system as claimed in claim 9 , wherein the controller electrically couples the fuel cell to the energy storage device without any intermediate power conditioning or power conversion.

14. A method comprising:

providing a fuel cell having a nominal voltage;

providing an energy storage device having a nominal voltage which is substantially similar to the nominal voltage of the fuel cell and electrically coupling the energy storage device to a load; and

selectively electrically coupling the fuel cell to the energy storage device to substantially maintain the energy storage device above a predetermined voltage threshold.

15. A method according to claim 14 , and wherein providing a fuel cell comprises electrically coupling a plurality of selectively removable fuel cell subracks together.

16. A method according to claim 14 , and further comprising:

providing a controller coupled in voltage sensing relation relative to the fuel cell and to the energy storage device;

monitoring the voltage of the energy storage device and the voltage of the fuel cell; and

controlling the electrical coupling of the fuel cell to the energy storage device with the controller responsive to the monitoring.

17. A method according to claim 16 , and further comprising:

providing a power conditioning device and electrically coupling the power conditioning device to both the energy storage device and the load.

18. A method according to claim 17 , and further comprising:

electrically coupling a sensor to the energy storage device to sense the voltage of the energy storage device and the voltage of the fuel cell, and electrically coupling the sensor to the controller.

19. A method according to claim 18 , and wherein providing a fuel cell comprises:

providing multiple independently operable fuel cells, and wherein the independently operable fuel cells may become inoperable without causing the remaining fuel cells to be rendered inoperable.

20. A method according to claim 14 , and wherein providing a fuel cell comprises:

providing a subrack for releasably supporting a plurality of ion exchange membrane fuel cell modules; and

providing a DC bus which releasably electrically couples with the ion exchange membrane fuel cell modules and electrically coupling the DC bus to the energy storage device.

Assignments (13)