Audi Ag

Leonard Liphardt

Sebastian Disson

Keigo Suematsu

Francisco Javier Valbuena Encinas

A method for operating a fuel cell device comprising a fuel cell stack having at least one fuel cell, involving the steps; a) drying of the fuel cell stack upon switching off the fuel cell device; b) determining the membrane residual water and the cathode residual water by means of electrochemical impedance spectroscopy when restarting the fuel cell device; c) using a cell voltage monitoring unit to identify the wettest cathode in one of the fuel cells; d) model-based determination of the water transport from the wettest cathode to the anode and thus the anode moisture in the fuel cell device; and; e) adjusting the electric current and the fuel volume flow in dependence on the anode moisture. A fuel cell device and a motor vehicle having a fuel cell device is also provided.

Method for operating a fuel cell device, the fuel cell device, and a motor vehicle outfitted with a fuel cell device

A method for starting a fuel cell device having a plurality of fuel cells under frost starting conditions is provided, which comprises: establishing the presence of frost starting conditions for the fuel cell device, anode-side supplying of a hydrogen-containing reactant and cathode-side supplying of an oxygen-containing reactant in a sub-stoichiometric ratio with an oxygen deficit, maintaining the supply of the reactants in a sub-stoichiometric ratio for a given interval of time, after elapsing of the interval of time, causing the complete discharging of the fuel cells in a discharge phase, and then converting the fuel cell device to a normal mode with the supplying of the reactants according to the requirements for the given operating state and the power demand. A fuel cell device and a motor vehicle are also provided for carrying out such a method.

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Mainhardt, Germany

Leonard Liphardt