The fuel cell system determines whether or not condensation is occurring in the anode gas and the cathode gas on the basis of the humidity of the cathode gas detected by a first humidity sensor provided in the power generation cells and the humidity of the anode gas detected by a second humidity sensor provided in the power generation cells, and adjusts the water content in the cathode gas and/or the anode gas in which condensation is occurring.

A fuel cell system includes a cathode system device, an anode system device, an ion detector, and a controller. When the concentration of fluoride ions exceeds a predetermined concentration threshold, the controller controls at least one of the cathode system device and the anode system device to adjust a load applied to the membrane electrode assemblies.

The present method relates to a method for ascertaining the relative humidity (RH) at a cathode inlet (113) of a fuel cell stack (110) of a fuel cell system (100), having the following steps: detecting at least one physical supply air parameter (ZP) of a supply air (ZU) to the cathode inlet (113), detecting a supply air mass flow (ZM) of the supply air (ZU), determining a supply air water mass flow (ZWM) on the basis of the at least one supply air parameter (ZP) detected and of the supply air mass flow (ZM) detected, detecting at least one physical cathode inlet parameter (KP) at the cathode inlet (113), determining a humidifier water mass flow (BWM) on the basis of the at least one cathode inlet parameter (KP) detected using a humidifier characteristic map (BK), ascertaining the relative humidity (RH) at the cathode inlet (113) on the basis of the supply air water mass flow (ZWM) determined, the humidifier water mass flow (BWM) determined and the at least one cathode inlet parameter (KP) detected.

The present invention relates to a determination device (1; 1′) for a fuel cell system (2; 2′) having a fuel cell stack (4), comprising a virtual moisture sensor (7) for recording predefined determination values and a computing unit (10) for calculating a moisture value in a cathode inlet region (5) upstream of a cathode section of the fuel cell stack (4) based on the recorded determination values. The invention further relates to a fuel cell system (2; 2′) having such a determination device (1; 1′), methods for determining the moisture value, a computer program product (11) and a storage means having a computer program product (11) stored thereon.

A fuel cell vehicle includes a fuel cell stack including a cathode flow field and an anode flow field, an atmospheric air pressure acquisition unit for obtaining pressure of atmospheric air, and a pump for sucking the atmospheric air and supplying an oxygen-containing gas to the cathode flow field through a supply channel. In the case where the temperature is predicted to be below freezing temperature after the time of stopping operation of the fuel cell stack, a scavenging period for the time of stopping operation is set based on the atmospheric air pressure, in order to perform scavenging of the cathode flow field by the oxygen-containing gas in a manner that the cathode flow field is placed in a predetermined humid state.

A system and method of controlling water imbalance in an electrochemical cell is provided. The method includes determining a present water imbalance in the electrochemical cell by summing a water.sub.in and a water.sub.created less a water.sub.out. Water.sub.in represents an amount of water introduced into the electrochemical cell by an oxidant feed gas; water.sub.created represents an amount of water created by the electrochemical cell from the electrochemical reaction; and water.sub.out represents an amount of water discharged from the electrochemical cell by an oxidant exhaust gas. The method includes tracking a cumulative water imbalance during operation of the electrochemical cell by repeatedly determining the present water imbalance and continuing to sum the results during operation. And, the method also includes adjusting a flow rate of the oxidant feed gas entering the electrochemical cell based on the cumulative water imbalance.

A fuel cell system includes a stack of proton exchange membrane (PEM) fuel cells defining a body, the body including a coolant inlet and coolant outlet, a cathode inlet and cathode outlet corresponding to a cathode, an anode inlet and an anode outlet corresponding to an anode. The fuel cell system also includes a cathode humidifier fluidly connected to the cathode inlet to provide a humidified inlet stream to the cathode inlet, an oxygen sensor positioned upstream of the cathode inlet and downstream of the cathode humidifier, and configured to measure oxygen content of the humidified inlet stream, and a controller connected to the cathode humidifier and the oxygen sensor and configured to operate the cathode humidifier based on the oxygen content of the humidified inlet stream.

A fuel cell system comprising: a fuel cell, a fuel gas supplier configured to supply fuel gas to an anode of the fuel cell, an oxidant gas supplier configured to supply oxidant gas to a cathode of the fuel cell, a humidity adjuster configured to adjust a relative humidity of the fuel gas and a relative humidity of the oxidant gas, and a controller, wherein the controller detects the relative humidity of the fuel gas at an anode inlet of the fuel cell, and the controller detects the relative humidity of the oxidant gas at a cathode outlet of the fuel cell, and wherein, based on detection results, the controller controls the humidity adjuster so that the relative humidity of the fuel gas at the anode inlet is higher than the relative humidity of the oxidant gas at the cathode outlet.

A method for humidifying a reactant in a fuel cell system is provided having a fuel cell stack, which is fluidically connected to a humidifier, wherein the humidifier comprises a membrane, on whose surface channels are formed. At least one of the channels is associated with a storage element for temporary storing of liquid water, the method involving the following steps: extracting the liquid water from the fuel cell stack and feeding the liquid water to the humidifier, admitting at least part of the liquid water into the storage element and temporarily storing the part therein, at least partially emptying the storage element by evaporating of the liquid water and humidifying of the reactant being supplied to the fuel cell stack by means of the evaporated liquid water, wherein the liquid water is extracted from the fuel cell stack both at the anode side and at the cathode side. A fuel cell system for carrying out the method is also provided.

A system and method of controlling water imbalance in an electrochemical cell is provided. The method includes determining a present water imbalance in the electrochemical cell by summing a water.sub.in and a water.sub.created less a water.sub.out. Water.sub.in represents an amount of water introduced into the electrochemical cell by an oxidant feed gas; water.sub.created represents an amount of water created by the electrochemical cell from the electrochemical reaction; and water.sub.out represents an amount of water discharged from the electrochemical cell by an oxidant exhaust gas. The method includes tracking a cumulative water imbalance during operation of the electrochemical cell by repeatedly determining the present water imbalance and continuing to sum the results during operation. And, the method also includes adjusting a flow rate of the oxidant feed gas entering the electrochemical cell based on the cumulative water imbalance.