Fuel cell assembly and method of control
View Patent ↗An exemplary method includes of operating a fuel cell at a first power output level that includes a plurality of operation parameters. Each operation parameter has a value to satisfy a first power demand. A change between the first power demand and a second power demand is determined. At least a first one of the operation parameters is maintained at a value corresponding to the first power output level or at an intermediate value while at least a second one of the operation parameters is changed to a value corresponding to a second power output level to satisfy the second power demand. The first operation parameter is delayed from changing to a value corresponding to the second power output level until a predetermined criterion is met.
1. A method of operating a fuel cell, comprising:
operating a fuel cell at a first power output level that includes a plurality of operation parameters, each operation parameter having a value corresponding to the first power output level to satisfy a first power demand;
determining a change between the first power demand and a second power demand;
maintaining at least a first one of the operation parameters at the value corresponding to the first power output level while changing at least a second one of the operation parameters to a value corresponding to a second power output level to satisfy the second power demand;
delaying changing the first operation parameter to a value corresponding to the second power output level until a predetermined criterion is met;
clipping a cell stack assembly voltage; and
selecting a voltage value for the clipping based on temperature.
2. The method of claim 1 , wherein the first power demand is greater than the second power demand.
3. The method of claim 2 , wherein changing the second operation parameter comprises reducing fuel cell pressure.
4. The method of claim 2 , wherein the first operation parameter includes at least one of reactant flow, humidity, or cell stack assembly voltage.
5. The method of claim 2 , comprising changing the first operation parameter to a value corresponding to an intermediate power output level between the first and second power output levels.
6. The method of claim 1 , wherein the first power demand is less than the second power demand.
7. The method of claim 6 , wherein the first operation parameter is pressure.
8. The method of claim 1 , wherein the predetermined criterion includes at least one of time and temperature of the fuel cell.
9. The method of claim 1 , wherein maintaining at least a first one of the operation parameters at the value corresponding to the first power output level while changing at least a second one of the operation parameters to a value corresponding to a second power output level to satisfy the second power demand comprises directing excess power to a power sink when the first demand is greater than the second demand.
10. The method of claim 1 , wherein the second operation parameter includes at least one of reactant flow, humidity, or cell stack assembly voltage.
11. The method of claim 1 , comprising decreasing the voltage value for the clipping as the temperature increases.
12. A fuel cell assembly comprising:
a cell stack assembly; and
a controller configured to:
operate the cell stack assembly at a first power output level that includes a plurality of operation parameters, each operation parameter having a value corresponding to a first power demand;
determine a change between the first power demand and a second power demand;
maintain at least a first one of the operation parameters at a value corresponding to the first power output level while changing at least a second one of the operation parameters to a value corresponding to a second power output level;
delay a change in the first operation parameter to a value corresponding to the second power output level until a predetermined criterion is met;
clip a cell stack assembly voltage; and
select a clip voltage value based on temperature.
13. The fuel cell assembly of claim 12 , wherein the first power demand is greater than the second power demand.
14. The fuel cell assembly of claim 13 , wherein changing the second operation parameter comprises reducing a pressure of the cell stack assembly.
15. The fuel cell assembly of claim 13 , wherein the first operation parameter includes at least one of reactant flow, humidity, or cell stack assembly voltage.
16. The fuel cell assembly of claim 13 , wherein changing the first operation parameter to a value corresponding to an intermediate power output level between the first and second power output levels.
17. The fuel cell assembly of claim 12 , wherein the first power demand is less than the second power demand.
18. The fuel cell assembly of claim 17 , wherein the first operation parameter comprises pressure.
19. The fuel cell assembly of claim 12 , wherein the second operation parameter includes at least one of reactant flow, humidity, or cell stack assembly voltage.
20. The fuel cell assembly of claim 12 , wherein the predetermined criterion includes at least one of time and temperature of the cell stack assembly.
21. The fuel cell assembly of claim 12 , wherein the controller is configured to direct excess power to a power sink when the first power demand is greater than the second power demand.
22. The fuel cell assembly of claim 21 , wherein the power sink includes at least one of a battery, a capacitor, or a resistor.
23. The fuel cell assembly of claim 12 , wherein the controller is configured to decrease the clip voltage value as the temperature increases.