Fuel cell power plant control
View Patent ↗An example method of controlling a fuel cell power plant based on provided power includes selectively varying an electrical resistance of the variable resistive device responsive to at least one of a power provided by the fuel cell power plant, a current provided by the fuel cell power plant, or a voltage decay rate.
1. A fuel cell power plant, comprising:
a cell stack assembly that provides a flow of electric power;
a variable resistive device operationally associated with the cell stack assembly, the variable resistive device having a selectively variable electrical resistance; and
a controller that automatically selects the electrical resistance of the resistive device to maintain a current of the flow of electrical power at an operating level based on a comparison of the current to a threshold current value stored in memory, wherein the threshold current value is between 10 and 50 mA/cm 2 .
2. The fuel cell power plant of claim 1 , wherein the controller is configured to select the electrical resistance responsive to a condition that is not a direct operating condition of the cell stack assembly.
3. The fuel cell power plant of claim 1 , wherein the variable resistive device is electrically coupled with the cell stack assembly.
4. The fuel cell power plant of claim 1 wherein the controller is configured to automatically select the electrical resistance of the resistive device to maintain the current of the flow of electrical power at an operating level above the threshold current value.
5. The fuel cell power plant of claim 1 wherein the controller is configured to maintain the electrical resistance at a steady value.
6. The fuel cell power plant of claim 1 wherein the controller is configured to use pulse width modulation to selectively vary the electrical resistance.
7. The fuel cell power plant of claim 1 wherein the controller is configured to dynamically vary the electrical resistance.
8. A fuel cell power plant, comprising:
a cell stack assembly that provides a flow of electric power;
a sensor device configured to sense the flow of electric power;
a variable resistive device operationally associated with the cell stack assembly, the variable resistive device having a selectively variable electrical resistance; and
a controller that controls the electrical resistance of the resistive device to maintain the flow of electric power at an operating level based on a comparison of the flow of electric power to a threshold electric power stored in memory.
9. The fuel cell power plant of claim 8 , wherein the controller is configured to decrease the selected electrical resistance as the cell stack assembly decays.
10. The fuel cell power plant of claim 8 , wherein the controller is configured to select the electrical resistance responsive to a condition that is not a direct operating condition of the cell stack assembly.
11. The fuel cell power plant of claim 8 , wherein the variable resistive device is electrically coupled with the cell stack assembly.
12. The fuel cell power plant of claim 8 wherein the controller is configured to maintain the electrical resistance at a steady value.
13. The fuel cell power plant of claim 8 wherein the controller is configured to use pulse width modulation to selectively vary the electrical resistance.
14. The fuel cell power plant of claim 8 wherein the controller is configured to dynamically vary the electrical resistance.
15. A method of controlling a fuel cell power plant, the method comprising:
selectively decreasing an electrical resistance of a variable resistive device responsive to a number of load-hours operated by the fuel cell power plant, wherein the decreasing tracks a voltage decay for the fuel cell power plant.
16. The method of claim 15 wherein selectively decreasing the electrical resistance includes using pulse width modulation to decrease the electrical resistance.
17. A method comprising:
controlling an electrical resistance of a variable resistor of a cell stack assembly of a fuel cell power plant to maintain a current of a flow of electric power generated by the cell stack assembly at an operating level based on a comparison of the current to a threshold current value between 10 and 50 mA/cm 2 .
18. The method of claim 17 wherein the controlling includes controlling the electrical resistance to maintain the current above the threshold current value.
19. The method of claim 17 wherein the controlling includes maintaining the electrical resistance at a steady value.
20. The method of claim 17 wherein the controlling includes using pulse width modulation to selectively vary the electrical resistance.
21. The method of claim 17 wherein the controlling includes dynamically varying the electrical resistance.