LOW COST METHOD AND SIGNAL PROCESSING ALGORITHM TO RAPIDLY DETECT ABNORMAL OPERATION OF AN INDIVIDUAL FUEL CELL IN A PLURALITY OF SERIES CONNECTED FUEL CELLS
First Claim
1. A method for monitoring a fuel cell stack including a plurality of series connected fuel cells, said method comprising:
- applying a frequency signal to the fuel cell stack;
measuring the voltage across the fuel cell stack;
measuring a current through the fuel cell stack;
calculating a real and complex impedance of the fuel cells using the measured voltage and the measured current; and
comparing the calculated impedance of the fuel cells to an optimal fuel cell impedance to determine fuel cell stack characteristics.
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Accused Products
Abstract
A system and method for determining reactant gas flow through a fuel cell stack to determine potential stack problems, such as a possible low performing fuel cell. The method includes applying a perturbation frequency to the fuel cell stack and measuring the stack current and stack voltage in response thereto. The measured voltage and current are used to determine an impedance of the stack fuel cells, which can then be compared to a predetermined fuel cell impedance for normal stack operation. If an abnormal fuel cell impedance is detected, then the fuel cell system can take corrective action that will address the potential problem.
11 Citations
23 Claims
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1. A method for monitoring a fuel cell stack including a plurality of series connected fuel cells, said method comprising:
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applying a frequency signal to the fuel cell stack; measuring the voltage across the fuel cell stack; measuring a current through the fuel cell stack; calculating a real and complex impedance of the fuel cells using the measured voltage and the measured current; and comparing the calculated impedance of the fuel cells to an optimal fuel cell impedance to determine fuel cell stack characteristics. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for monitoring reactant gas flows through a fuel cell stack including a plurality of series connected fuel cells, said method comprising:
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applying a frequency signal having a first frequency to the fuel cell stack by selectively connecting and disconnecting a load across the stack to monitor an air flow through a cathode side of the fuel cell stack; applying a frequency signal having a second frequency to the fuel cell stack by selectively connecting and disconnecting a load across the stack to monitor a hydrogen gas flow through an anode side of the fuel cell stack, where the first and second frequencies are different; measuring the voltage across the fuel cell stack as the frequency signal is being applied; measuring a current through the fuel cell stack as the frequency signal is being applied; calculating a real and complex impedance of the fuel cells using the measured voltage and the measured current; and comparing the calculated impedance of the fuel cells to an optimal fuel cell impedance to determine whether the reactant gas flow is optimal for the current stack operating conditions. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A system for monitoring reactant gas flows through a fuel cell stack including a plurality of series connected fuel cells, said system comprising:
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means for applying a frequency signal having a first frequency to the fuel cell stack by selectively connecting and disconnecting a load across the stack to monitor an air flow through a cathode side of the fuel cell stack; means for applying a frequency signal having a second frequency to the fuel cell stack by selectively connecting and disconnecting a load across the stack to monitor a hydrogen gas flow through an anode side of the fuel cell stack, where the first and second frequencies are different; means for measuring the voltage across the fuel cell stack as the frequency signal is being applied; means for measuring a current through the fuel cell stack as the frequency signal is being applied; means for calculating a real and complex impedance of the fuel cells using the measured voltage and the measured current; means for calculating a ratio of calculated impedance values; and means for comparing the ratio of calculated impedance of the fuel cells to an optimal fuel cell impedance to determine whether the reactant gas flow is optimal for the current stack operating conditions. - View Dependent Claims (20, 21, 22, 23)
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Specification