METHOD FOR OPERATING A FUEL CELL SYSTEM

The invention relates to a method of operating a fuel cell system (), with a fuel cell stack (), to which a mass gas flow () with an oxidation agent is supplied via a gas conveying system (), wherein the gas conveying system () comprises at least one compressor driven by an electric motor () having a pumping limit () and at least one turbine (), driven by an exhaust mass flow () of the fuel cell stack (), which comprises a cathode path having a cathode mass flow rate and a cathode pressure, wherein the compressor () can be driven at a variable speed, wherein the turbine () is associated with a turbine bypass () with a turbine bypass valve (), wherein a stack bypass () is associated with the fuel cell stack () with a stack bypass valve (), wherein the fuel cell system () operates in different operating ranges, in which the cathode mass flow and the cathode pressure are controlled.