Patent ID: 8192879

Claim:
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.