(WO9832185-A1)      A method of operating a polymer-electrolyte-membrane (PEM-) fuel cell arrangement which includes at least one PEM-fuel cell stack (4) having an input-side connected revs-controlled compressor (8) for supplying the air-volume flow V2, in which the revs n of the compressor (8) are controlled to a desired value nsn in order to adjust the electrical current I of the PEM-fuel cell stack (4) to a specified value ISN, wherein the desired value nsn is derived from the specified value ISN of the electrical current I.    More specifically, the desired value nsn of the revs m for the revs-controlled compressor (8) are specified by a control unit (18).    USE -   For application e.g. in motor vehicles as exhaust- gas-free electrical drive.    ADVANTAGE -   Provides simplified control of air volume flow for PEM-fuel cell stack.    (EP956605-A1)      A method of operating a polymer-electrolyte-membrane (PEM-) fuel cell arrangement which includes at least one PEM-fuel cell stack (4) having an input-side connected revs-controlled compressor (8) for supplying the air-volume flow V2, in which the revs n of the compressor (8) are controlled to a desired value nsn in order to adjust the electrical current I of the PEM-fuel cell stack (4) to a specified value ISN, wherein the desired value nsn is derived from the specified value ISN of the electrical current I.    More specifically, the desired value nsn of the revs m for the revs-controlled compressor (8) are specified by a control unit (18).    USE -   For application e.g. in motor vehicles as exhaust- gas-free electrical drive.    ADVANTAGE -   Provides simplified control of air volume flow for PEM-fuel cell stack.    (JP2000508471-W)      A method of operating a polymer-electrolyte-membrane (PEM-) fuel cell arrangement which includes at least one PEM-fuel cell stack (4) having an input-side connected revs-controlled compressor (8) for supplying the air-volume flow V2, in which the revs n of the compressor (8) are controlled to a desired value nsn in order to adjust the electrical current I of the PEM-fuel cell stack (4) to a specified value ISN, wherein the desired value nsn is derived from the specified value ISN of the electrical current I.    More specifically, the desired value nsn of the revs m for the revs-controlled compressor (8) are specified by a control unit (18).    USE -   For application e.g. in motor vehicles as exhaust- gas-free electrical drive.    ADVANTAGE -   Provides simplified control of air volume flow for PEM-fuel cell stack.    (US6180271-B1)      A method of operating a polymer-electrolyte-membrane (PEM-) fuel cell arrangement which includes at least one PEM-fuel cell stack (4) having an input-side connected revs-controlled compressor (8) for supplying the air-volume flow V2, in which the revs n of the compressor (8) are controlled to a desired value nsn in order to adjust the electrical current I of the PEM-fuel cell stack (4) to a specified value ISN, wherein the desired value nsn is derived from the specified value ISN of the electrical current I.    More specifically, the desired value nsn of the revs m for the revs-controlled compressor (8) are specified by a control unit (18).    USE -   For application e.g. in motor vehicles as exhaust- gas-free electrical drive.    ADVANTAGE -   Provides simplified control of air volume flow for PEM-fuel cell stack.