Fuel cell stack monitoring and system control
First Claim
1. In a method for operating a fuel cell system having a fuel processor which supplies a hydrogen-rich stream to a stack of fuel cells, wherein said hydrogen reacts with an oxidant to supply electrical power to an external load, the improvement comprising:
- (a) monitoring actual voltage and actual current from the fuel cell stack;
(b) determining an expected magnitude of voltage as a function of said actual current based on a predetermined relationship between voltage and current;
(c) calculating a variance value between said actual voltage and said expected voltage magnitudes; and
(d) generating a signal if said calculated variance value exceeds a predetermined variance value.
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Abstract
A control method for monitoring a fuel cell stack in a fuel cell system in which the actual voltage and actual current from the fuel cell stack are monitored. A preestablished relationship between voltage and current over the operating range of the fuel cell is established. A variance value between the actual measured voltage and the expected voltage magnitude for a given actual measured current is calculated and compared with a predetermined allowable variance. An output is generated if the calculated variance value exceeds the predetermined variance. The predetermined voltage-current for the fuel cell is symbolized as a polarization curve at given operating conditions of the fuel cell. Other polarization curves may be generated and used for fuel cell stack monitoring based on different operating pressures, temperatures, hydrogen quantities.
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Citations
10 Claims
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1. In a method for operating a fuel cell system having a fuel processor which supplies a hydrogen-rich stream to a stack of fuel cells, wherein said hydrogen reacts with an oxidant to supply electrical power to an external load, the improvement comprising:
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(a) monitoring actual voltage and actual current from the fuel cell stack;
(b) determining an expected magnitude of voltage as a function of said actual current based on a predetermined relationship between voltage and current;
(c) calculating a variance value between said actual voltage and said expected voltage magnitudes; and
(d) generating a signal if said calculated variance value exceeds a predetermined variance value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a method for operating a fuel cell system having a fuel processor which supplies a hydrogen-rich stream to a stack of fuel cells, wherein said hydrogen reacts with an oxidant to supply electrical power to an external load, the improvement comprising:
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(a) establishing a predetermined relationship between voltage and current for a fuel cell stack;
(b) monitoring actual voltage and actual current from the fuel cell stack;
(c) then either;
(1) determining an expected value of voltage as a function of the actual current based on the predetermined relationship;
or(2) determining an expected value of current as a function of the actual voltage based on the predetermined relationship;
(d) calculating the variance between said actual and expected values; and
(e) generating a signal if the calculated variance exceeds a predetermined variance value.
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Specification