Air system pressure observer control method for fuel cell system

A system for controlling gas flow in a fuel cell circuit includes a fuel cell stack, a pressure sensor, and a valve to adjust a flow of gas through the fuel cell circuit. The system further includes an ECU designed to estimate pressure values of the gas at multiple locations in the fuel cell circuit based on the detected pressure of the gas and based on flow resistance values (including at the valve), the estimated pressure values including an estimated sensor pressure value at a location of the pressure sensor. The ECU is further designed to determine a pressure deviation between the detected pressure and the estimated sensor pressure value. The ECU is further designed to adjust the flow resistance value of the valve to determine a final flow resistance value of the valve that causes the pressure deviation to reach or drop below a threshold deviation amount.