Abstract: The present invention relates to a fuel cell system (100) for converting energy.

Abstract: The invention relates to a method for operating a fuel cell system (BS), having the steps of determining (S1) a gas concentration of a hydrogen and/or a concentration of a foreign gas in a gaseous fuel on an anode side (A) of a fuel cell (BZ) while operating a fuel cell (BZ); comparing (S2) the gas concentration of the hydrogen to a specified hydrogen concentration value and/or comparing the concentration of the foreign gas to a specified foreign gas concentration value; opening (S3) a discharge valve (AV) in a recirculation circuit (RZ), wherein the recirculation circuit (RZ) is connected to the anode side (A) and the gaseous fuel is at least partially discharged out of the recirculation circuit (RZ) via the discharge valve (AV) when the gas concentration of the hydrogen falls below the specified hydrogen concentration value and/or when the concentration of the foreign gas exceeds the specified foreign gas concentration value; introducing (S4) fresh hydrogen from a hydrogen supply line (WL) into the recircul

Abstract: The invention relates to an operating method (100) for operating a fuel cell system (300) for providing electrical energy for a consumer. The operating method (100) comprises the steps of activating (101) a shut-down procedure of the fuel cell system (300) in response to the receipt of a shut-down command. The shut-down procedure comprises shutting down an air supply unit (305) for supplying air to a cathode sub-system (303) of the fuel cell system (300) in order to reduce oxygen introduced to the cathode sub-system (303) and a voltage provided by the fuel cell system (300), activating (103) a reactivation procedure of the fuel cell system (300) in response to a receipt of a start-up command, if the start-up command is received within a predefined time period after the shut-down command, wherein the reactivation procedure involves increasing the speed of the air supply unit (305) directly after receipt of the start-up command.

Abstract: A method for starting a fuel cell system comprising: determining a first pressure difference between a first pressure, which is present in an anode chamber of the fuel cell system, the anode chamber being connected to an anode of at least one fuel cell, and an ambient pressure; determining a second pressure difference between a second pressure, which is present in a cathode chamber of the fuel cell system, the cathode chamber being connected to a cathode of the at least one fuel cell, and the ambient pressure; comparing the first pressure difference to a first threshold value; comparing the second pressure difference to a second threshold value; performing a pressure equalization between the anode chamber and the cathode chamber if the first pressure difference exceeds the ambient pressure by more than the first threshold value and/or if the second pressure difference exceeds the ambient pressure by more than the second threshold value; and feeding fuel into the anode chamber.

Abstract: The invention relates to a method for operating a fuel cell system (1) comprising a fuel cell stack (2) having a cathode (3) and an anode (4), wherein air is supplied to the cathode (3) via a supply air path (5), and exhaust air exiting the fuel cell stack (2) is discharged via an exhaust air path (6), and wherein the anode (4) is supplied with hydrogen via an anode circuit (7). According to the invention, when the fuel cell system (1) is switched off, the cathode (3) is shut off and the oxygen concentration of the air in the cathode (3) is minimized, and, when the system is subsequently restarted and the cathode (3) remains shut off, the following steps are then carried out: a) the anode (4) is flushed with hydrogen, b) at least one cell voltage and/or the total voltage of the fuel cell stack (2) is or are measured and used to detect a leakage point. The invention also relates to a control device for carrying out steps of a method according to the invention.

Abstract: The invention relates to a method (100) for operating a fuel cell system (200), the method (100) comprising: a first determination step (101), in which a hydrogen concentration supplied to a fuel cell stack (203) of the fuel cell system (200) by means of an inlet valve (209) of the fuel cell system (200) is determined, a second determination step (103), in which a nitrogen volume flow flowing through the fuel cell stack (203) is determined, and an adjustment step (105), in which a rotational speed of a recirculation fan (205) of the fuel cell system (200) is adjusted on the basis of the determined hydrogen concentration and the determined nitrogen volume flow. The invention also relates to a fuel cell system (200) and a to computer program product according to the appended claims.

Abstract: The present invention relates to a method for operating a target fuel cell system (200), to a fuel cell system (200) having a control apparatus (201) and to a computer program product containing program code means according to the appended claims.