Method to perform adaptive voltage suppression of a fuel cell stack based on stack parameters

A method for maintaining an output voltage of fuel cells in a fuel cell stack at or below a maximum voltage, said method comprising:

• providing a desired voltage set-point value that defines a predetermined maximum fuel cell voltage value;
• modifying the desired voltage set-point value by applying the desired voltage set-point value to a ramp limiter to vary the desired voltage set-point value from an initial voltage set-point value to the desired voltage set-point value;
• determining an error value between the modified voltage set-point value and an average fuel cell voltage from the fuel cells in the fuel cell stack;
• determining a minimum gross power prediction value using the modified voltage set-point to prevent the fuel cell voltage from going above the predetermined maximum fuel cell voltage value that includes obtaining predetermined stack parameters from a memory, determining the stack current required to maintain the voltage suppressed to the modified voltage set-point value and using the stack current to determine the minimum gross power prediction value;
• determining a supplemental power value based on the minimum gross power prediction value and the error value to determine how much power needs to be drawn from the stack to maintain the fuel cell voltage below the predetermined maximum fuel cell voltage value;
• charging a battery using stack power based on the supplemental power value to reduce the fuel cell voltage;
• and
• coupling an auxiliary load to the fuel cell stack to reduce the fuel cell voltage if a maximum battery charge limit is reached or may be reached.

A system for maintaining an output voltage of fuel cells in a fuel cell stack at or below a maximum voltage, said system comprising:

• means for determining a desired voltage set-point value using a cell voltage model and a stack polarization curve;
• means for modifying the desired set-point value including increasing the desired voltage set-point value from an initial set-point value to the desired voltage set-point value;
• means for generating an error value between the modified voltage set-point value and an average fuel cell voltage from the fuel cells in the fuel cell stack;
• means for determining a minimum gross power prediction value using the modified voltage set-point value to prevent the fuel cell stack voltage from going above the desired set-point value;
• means for determining a supplemental power value based on the minimum gross prediction value and the error value to determine how much power needs to be drawn from the stack to maintain the fuel cell voltage below the desired set-point value;
• means for charging a battery using stack power based on the supplemental power value to reduce the fuel cell voltage;
• and
• means for coupling an auxiliary load to the fuel cell stack to reduce the fuel cell voltage if a maximum battery charge limit is reached or may be reached.