Patent ID: 8606436

Claim:
A device for controlling the air humidity in a fuel cell, comprising: at least one detection unit connected to the fuel cell that detects the output voltage of the fuel cell; at least one interrupter unit; and at least one processor unit connected to the interrupter unit and including a first signal input that is connected to a signal output of the detection unit, and a first signal output that is connectable to a control input of a humidity control unit of the fuel cell, wherein the processor unit interrupts the connection between the fuel cell and an electrical load for a time period T by triggering the interrupter unit and determines a time constant of the fuel cell from a step response of the voltage progression of the fuel cell and actuates the humidity control unit as a function of a deviation of the determined time constant from a predetermined time constant and the processor unit determines at least a double-layer capacitance and a charge transfer resistance of the fuel cell from the step response and compares the determined double-layer capacitance with a predetermined double-layer capacitance and actuates the humidity control unit as a function of a respective deviation.