Method for maximum net power calculation for fuel cell system based on online polarization curve estimation
First Claim
1. A method for estimating the maximum stack power from a fuel cell stack during operation of the fuel cell stack, said method comprising:
- executing at any time during operation of the fuel cell stack, using at least one computing device coupled to a memory, instructions for;
selecting an average cell voltage limit;
selecting a minimum cell voltage limit;
estimating a separate polarization curve of the fuel cell stack for both an average cell voltage and a minimum cell voltage;
executing an algorithm to determine a maximum current density for each of the average cell voltage polarization curve and the minimum cell voltage polarization curve, the algorithm including;
separating a current density range of the fuel cell stack into a predetermined number of sample regions in ascending order;
selecting a first sample region and a current density corresponding to the first sample region;
calculating an average cell voltage and a minimum cell voltage at the current density selected for the first sample region being examined;
determining whether the average cell voltage is less than the average cell voltage limit;
selecting a next sample region in the current density range and a current density corresponding to the next sample region if the average cell voltage is not less than the average cell voltage limit;
setting the current density selected for the sample region being examined as the maximum current density for the average cell voltage polarization curve when the average cell voltage is less than the average cell voltage limit;
calculating a maximum net power using the maximum current density estimated at the average cell voltage limit;
determining whether the minimum cell voltage is less than the minimum cell voltage limit;
selecting a next sample region in the current density range and a current density corresponding to the next sample region if the minimum cell voltage is not less than the minimum cell voltage limit;
setting the current density selected for the sample region being examined as the maximum current density for the minimum cell voltage polarization curve when the minimum cell voltage is less than the minimum cell voltage limit;
calculating a maximum net power using the maximum current density estimated at the minimum voltage limit; and
selecting as the maximum stack power, the lesser of the maximum net power using the maximum current density estimated at the average cell voltage limit and the maximum net power using the maximum current density estimated at the minimum voltage limit.
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Abstract
An algorithm for determining the maximum net power available from a fuel cell stack as the stack degrades over time using an online adaptive estimation of a polarization curve of the stack. The algorithm separates the current density range of the stack into sample regions, and selects a first sample region from the far left of the estimated polarization curve. The algorithm then calculates the cell voltage for that current density sample region, and determines whether the calculated cell voltage is less than or equal to a predetermined cell voltage limit. If the calculated cell voltage is not less than the cell voltage limit, then the algorithm selects the next sample region along the polarization curve. When the calculated cell voltage does reach the cell voltage limit, then the algorithm uses that current density for the sample region being analyzed to calculate the maximum power of the fuel cell stack.
10 Citations
20 Claims
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1. A method for estimating the maximum stack power from a fuel cell stack during operation of the fuel cell stack, said method comprising:
executing at any time during operation of the fuel cell stack, using at least one computing device coupled to a memory, instructions for; selecting an average cell voltage limit; selecting a minimum cell voltage limit; estimating a separate polarization curve of the fuel cell stack for both an average cell voltage and a minimum cell voltage; executing an algorithm to determine a maximum current density for each of the average cell voltage polarization curve and the minimum cell voltage polarization curve, the algorithm including; separating a current density range of the fuel cell stack into a predetermined number of sample regions in ascending order; selecting a first sample region and a current density corresponding to the first sample region; calculating an average cell voltage and a minimum cell voltage at the current density selected for the first sample region being examined; determining whether the average cell voltage is less than the average cell voltage limit; selecting a next sample region in the current density range and a current density corresponding to the next sample region if the average cell voltage is not less than the average cell voltage limit; setting the current density selected for the sample region being examined as the maximum current density for the average cell voltage polarization curve when the average cell voltage is less than the average cell voltage limit; calculating a maximum net power using the maximum current density estimated at the average cell voltage limit; determining whether the minimum cell voltage is less than the minimum cell voltage limit; selecting a next sample region in the current density range and a current density corresponding to the next sample region if the minimum cell voltage is not less than the minimum cell voltage limit; setting the current density selected for the sample region being examined as the maximum current density for the minimum cell voltage polarization curve when the minimum cell voltage is less than the minimum cell voltage limit; calculating a maximum net power using the maximum current density estimated at the minimum voltage limit; and selecting as the maximum stack power, the lesser of the maximum net power using the maximum current density estimated at the average cell voltage limit and the maximum net power using the maximum current density estimated at the minimum voltage limit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for estimating the maximum stack power from a fuel cell stack during operation of the fuel cell stack, said method comprising:
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executing during operation of the fuel cell stack, using at least one computing device coupled to a memory, instructions for; selecting at least one cell voltage limit for a fuel cell in the fuel cell stack; estimating a polarization curve of the fuel cell stack for at least one cell; separating a current density range of the fuel cell stack into a predetermined number of sample regions; selecting a first sample region; determining a cell voltage at a current density for the selected sample region; determining whether the cell voltage is less than the cell voltage limit; selecting a next sample region in the current density range if the cell voltage is not less than the cell voltage limit; and calculating a maximum net power for the cell voltage if the cell voltage is less than the cell voltage limit. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A system for estimating the maximum stack power from a fuel cell stack during operation of a fuel cell stack, said system comprising;
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means for selecting an average cell voltage limit; means for selecting a minimum cell voltage limit; means for estimating a polarization curve of the fuel cell stack for both an average fuel cell and a minimum fuel cell voltage; means for separating a current density range of the fuel cell stack into a predetermined number of sample regions; means for selecting a first sample region; means for determining an average cell voltage and a minimum cell voltage at the current density for the selected sample region; means for determining whether the average cell voltage and the minimum cell voltage are less than the average cell voltage limit and the minimum cell voltage limit, respectively; means for selecting a next sample region in the current density range if the average cell voltage is not less than the average cell voltage limit; means for selecting a next sample region in the current density range if the minimum cell voltage is not less than the minimum cell voltage limit; means for calculating a maximum net power for the average cell voltage when the average cell voltage is less than the average cell voltage limit and for calculating a maximum net power for the minimum cell voltage when the minimum cell voltage is less than the minimum cell voltage limit; and means for selecting the less of the average cell voltage maximum net power and the minimum cell voltage maximum net power as a maximum stack power. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification