Abstract: Disclosed are an apparatus for measuring an impedance of a fuel cell in a system to which a DC-DC converter is applied and a method thereof. The method includes calculating an impedance of a fuel cell stack based on an impedance of an output terminal of the fuel cell stack measured in a state in which the output of the fuel cell stack is drawn and the impedance of the output terminal of the fuel cell stack measured in a state in which the drawing of the output of the fuel cell stack is stopped.

Abstract: A method for accurately measuring the impedance of the fuel cell stack in the vehicle during operation of the vehicle includes determining whether measuring the impedance of the fuel cell stack is requested during driving of the vehicle driven by using a power of a fuel cell stack, switching a DC-DC converter connecting the fuel cell stack and a battery to each other to a buck mode when measuring the impedance is requested, thereby blocking output current of the fuel cell stack from flowing to the battery through the DC-DC converter, determining a first current value of the fuel cell stack for measuring the impedance, controlling a resistance value of a COD variable resistor consuming the output current of the fuel cell stack according to the first current value, and measuring the impedance of the fuel cell stack while the output current of the fuel cell stack is maintained at the first current value.

Abstract: A fuel cell power plant includes an energy storage system connected in parallel with a fuel cell system. The fuel cell system includes a controller, a fuel flow system, an air flow system, and an internal water management system. The controller is operable to receive, as inputs, the energy storage system state of charge and the power demand from an electric load. The controller is further operable to determine a power split set point and execute commands, as output, to control operation of the air flow system, wherein the air flow system actively regulates the proportion of current flow between the fuel cell system and the energy storage system to meet the power demand of the electric load.

Abstract: A fuel cell stack includes a plurality of fuel cells received between two end plates, at least one end plate of which has flow channels formed therein with ports for the anode fresh gas and the anode exhaust gas as well as ports for the cathode fresh gas and the cathode exhaust gas, wherein a hygroscopic material forms the wall between the ports for the anode exhaust gas and the cathode fresh gas.

Abstract: A fuel cell vehicle includes a battery disposed in a first space, a radiator disposed in a second space formed adjacent to the first space in a second direction intersecting a first direction, which is a direction in which the vehicle travels, and at least one fuel cell unit disposed in a third space formed adjacent to the first space in the second direction while being spaced apart from the second space in the second direction, with the first space interposed therebetween.

Abstract: A DC voltage distribution arrangement and method of controlling a DC voltage distribution system, the DC voltage distribution system including a DC voltage bus, a fuel cell electrically connected to the DC voltage bus, an energy storage and an energy storage converter, wherein the input of the energy storage converter is connected to the energy storage and the output of the energy storage converter is connected to the DC bus. The method comprises providing a DC voltage reference for the energy storage converter, the energy storage converter controlling the voltage of the DC voltage bus by providing power from the energy storage or to the energy storage, detecting power flow of the energy storage converter, and changing the DC voltage reference on the basis of the detected power flow to change the power taken from the fuel cell.

Abstract: A method of correcting error of hydrogen pressure sensor of vehicle fuel cell system, may checking, whether an opening ratio of a hydrogen pressure regulation valve is in a normal range by use of data map; checking whether a hydrogen purge valve is opened when the opening ratio of the hydrogen pressure valve is not within the normal range; changing the opening ratio of the hydrogen pressure regulation valve at least one time when the hydrogen purge valve is determined as being opened, and detecting two or more measurement values of the hydrogen pressure sensor at two or more different opening ratios of the hydrogen pressure regulation valve; and comparing, the two or more measurement values of the hydrogen pressure sensor detected at the two more opening ratios, respectively with predetermined pressure values corresponding to the opening ratios, and correcting errors between the measurement values and the predetermined pressure values.

Abstract: A current limiting method of a fuel cell stack is capable of preventing current of the fuel cell stack from rapidly dropping to prevent jerking or shock from occurring while a vehicle travels. The method includes: determining whether performance deterioration of a unit cell of the fuel cell stack has occurred, employing a feed forward control type current limiting logic of the fuel cell stack before an output of the fuel cell vehicle is lowered, decreasing the current of the fuel cell stack to a predetermined level by the feed forward control type current limiting logic, and gradually restoring the current of the fuel cell stack to a maximum current usage value from a point in time when the current of a load is used.

Abstract: A fuel cell unit includes: a first case housing a fuel cell stack; a second case housing a power converter; an adapter fixing the first and second cases together; and a conductive member connecting between the fuel cell stack and the power converter. A first flange portion, surrounding a first opening portion, of the first case and a second flange portion, surrounding a second opening portion, of the second case are different in at least one of shape and size. The adapter includes: a third flange portion corresponding to the first flange portion; a fourth flange portion corresponding to the second flange portion; a surrounding wall portion continuous from the third flange portion to the fourth flange portion to define an internal space communicating with openings inside the third and fourth flange portions; and a partition wall portion between the first opening portion and the second opening portion.

Abstract: A fuel cell vehicle includes a fuel cell, a gas supply unit, a friction brake system, a drive motor, an electric storage device, and a control unit configured to execute control of obtaining requested braking force with use of friction braking force and regenerative braking force and control of performing a scavenging process. When the fuel cell vehicle is in braking with the friction braking force and the regenerative braking force, the control unit is configured to determine whether or not a scavenging preparation condition is satisfied with use of the amount of stagnant water stagnating in the fuel cell, execute a responsiveness enhancement process when the scavenging preparation condition is executed, and execute a scavenging process when the responsiveness enhancement process is completed, and the amount of the stagnant water reaches a reference value.

Abstract: A power supply system for a vehicle includes a high-voltage battery that supplies electric power to an on-vehicle motor, a low-voltage battery that supplies electric power to a plurality of on-vehicle auxiliary machines, a DC/DC converter that changes voltage of an output from the high-voltage battery and supplies the resulting output to the low-voltage battery, and a controller that detects a working state of at least one of the plurality of on-vehicle auxiliary machines and controls operation of the DC/DC converter in accordance with the detected working state.

Abstract: The present disclosure relates to a method of manufacturing an electrolyte membrane for fuel cells capable of effectively removing hydrogen and/or air crossing over. Specifically, the method includes coating a slurry including at least an ionomer on a substrate to manufacture an ion transfer layer, manufacturing a laminate including the substrate and the ion transfer layer, and providing a pair of laminates to form an electrolyte membrane, wherein the ion transfer layer has a catalyst region formed at one side thereof based on a width-direction center line thereof, the catalyst region including a catalyst.

Abstract: A fuel cell system includes a fuel feeder that supplies fuel, a fuel cell stack that generates power through an electrochemical reaction using air and a hydrogen-containing gas generated from the fuel, a first temperature sensor that senses the temperature of the fuel cell stack, and a controller. The fuel cell stack has a membrane electrode assembly including an electrolyte membrane through which protons can pass, a cathode on one side of the electrolyte membrane, and an anode on the other side of the electrolyte membrane. The controller defines an upper limit of current output from the fuel cell stack on the basis of the temperature of the fuel cell stack, the supply of the fuel, and the hydrogen consumption of the fuel cell stack associated with internal leakage current and keeps the current output from the fuel cell stack at or below the upper limit.

Abstract: A control method and system of a fuel cell system are provided. The control method includes draining the voltage of a fuel cell stack by charging a high voltage battery. In addition, the method includes draining the voltage of the fuel cell stack by connecting a fuel cell load device to the fuel cell stack, which is performed when the voltage of the fuel cell stack decreased by the first draining process is less than a predetermined first reference voltage.

Abstract: An operating control method of a fuel cell stack is provide. The method includes diagnosing performance of a fuel cell stack based on an output current of the fuel cell stack, when an operating voltage of the fuel cell stack is within a predetermined diagnostic voltage range. Whether a recovery operation of the fuel cell stack is required is determined based on the diagnosed performance of the fuel cell stack and the voltage of the fuel cell stack is reduced, when the recovery operation of the fuel cell stack is required to recover performance of the fuel cell stack.

Abstract: A method for controlling an output of a fuel cell stack is provided. The method includes calculating a total requirement current value to be output from a plurality of fuel cell stacks in a fuel cell electric vehicle (FCEV) including the plurality of fuel cell stacks. The calculated total requirement current value is then allocated to each fuel cell stack based on a voltage of the fuel cell stack.

Abstract: An elastomeric cell frame for a fuel cell includes an insert in which a membrane electrode assembly and a pair of gas diffusion layers disposed on both surfaces of the insert have been bonded; a separator assembly disposed on one of the surfaces of the insert while a pair of separators is configured to face each other; and a sheet-shaped elastomeric frame disposed to surround a rim of the insert and a rim of the separator assembly and a side surface thereof in outside regions of the insert and the separator assembly, and integrally bonded with the rim of the insert and the rim of the separator assembly by thermal bonding.

Abstract: A second flange is separated from at least one of ribs located at one end and the other end out of a plurality of ribs of a plurality of first cases which are located next to each other in a second direction, and is fixed to one of the ribs except for the at least one of the ribs.

Abstract: A fuel cell system and a method for operating the fuel cell system, wherein the fuel cell system includes a fuel cell, a controller, a switch, an oxygen supply device and an output circuit. The fuel cell includes an anode and a cathode. The fuel cell is a cathode enclosed fuel cell. The controller is used to drive control signal for adjusting the electrochemical metering ratio of oxygen flow, supplied by the oxygen supply device, to output current, wherein the electrochemical metering ratio is ‘a’, and ‘a’ satisfies: 1?a?4. The method of the present disclosure uses the fuel cell system of the present disclosure, which optimizes the performance of a fuel cell and makes the output interruption time very short; hence it is highly beneficial for providing a more stable output.

Abstract: A method for controlling the operation of an electrochemical device having at least one operating organ, comprising the steps of: receiving measurements related to the operation of the electrochemical device, and estimating at least diagnostics data based on said measurements, estimating prognostics data based on said diagnostics data and providing operation instructions to control said operating organ of the electrochemical device, said operation instructions being optimized with respect to said estimated diagnostics and prognostics data.

Abstract: The present disclosure provides systems and methods useful in capture of one more moieties (e.g., carbon dioxide) from a gas stream (i.e., direct air capture). In various embodiments, the systems and methods can utilize at least a scrubbing unit, a regeneration unit, and an electrolysis unit whereby an alkali solution can be used to strip the moiety (e.g., carbon dioxide) from the gas stream, the removed moiety can be regenerated and optionally purified for capture or other use, and a formed salt can be subjected to electrolysis to recycle the alkali solution back to the scrubber for re-use with simultaneous production of one or more further chemicals.

Abstract: A battery module for use with an electric vehicle is disclosed. In one aspect, the battery module includes a power source and an isolation monitoring circuit electrically connected with the power source. The electric vehicle includes a Y-capacitor module. The isolation monitoring circuit can discharge the Y-capacitor module when the battery module is electrically connected with the electric vehicle. According to at least one of the disclosed embodiments, no additional HV efforts to discharge a Y-capacitor, and discharge of a vehicle Y-capacitor can be performed on the battery side.

Abstract: Provided is a fuel cell system including: a fuel cell; a reactant gas supply section; a converter; an alternating-current superimposing unit; a phase difference deriving unit configured to derive a phase difference that is a phase lag of an alternating-current voltage relative to an alternating current in an alternating-current component output from the fuel cell; and a first inference unit. The first inference unit infers that the fuel cell is in an inappropriate wet state, when the absolute value of an amount of change in the phase difference has become equal to or larger than a predetermined criterion value immediately after the magnitude of a change in the value of at least one of parameters that are a flow rate of a reactant gas, a stoichiometric ratio, and an output current has exceeded a predetermined criterion.

Abstract: When operation is to be started in a state where the SOC of a high-voltage battery has dropped, an exhaust gas recirculation pump is driven by a low-voltage battery to suck in atmosphere through an air intake valve. The atmosphere is supplied to a fuel cell stack as oxygen-containing gas, while fuel gas is supplied from a fuel tank thereto, whereby power generation is performed to thereby charge the high-voltage battery. Normal power generation of the fuel cell system is performed using the high-voltage power of the charged high-voltage battery.

Abstract: A formed substrate assembly includes an air flow form plate, a fuel flow form plate, and an anode. The fuel flow form plate is positioned over the air flow form plate. The fuel flow form plate partially defines a plurality of first channels. The fuel flow form plate also defines a plurality of second channels. The plurality of second channels defines a plurality of apertures, where a portion of the apertures extend from the plurality of second channels to the plurality of first channels. The anode is positioned over the fuel flow form plate. The anode partially defines the plurality of first channels such that the fuel flow form plate and the anode define the plurality of first channels. The portion of the plurality of apertures is configured to channel a flow of fuel from the plurality of second channels to the plurality of first channels.

Abstract: An energy management system for an aircraft, wherein the energy management system comprises a fuel cell configured to convert chemical energy into electric energy, at least one energy source configured to provide electric energy, at least one electrical load, an electric bus electrically coupled to the fuel cell, the at least one energy source, and the at least one electrical load, and a controller configured to control the at least one electrical load in such a manner that a minimum load to the fuel cell is ensured. Furthermore, an aircraft comprises such energy management system. A method for managing energy in a system comprises electrically coupling a fuel cell, at least one energy source, and at least one electrical load by an electric bus, and controlling at least one electrical load in such a manner that a minimum load to the fuel cell is ensured.

Abstract: A system and method for controlling hydrogen purging of a fuel cell are provided. The method includes calculating a hydrogen supply amount and estimating a hydrogen consumption amount. An estimated hydrogen concentration is then corrected when a difference between the calculated hydrogen supply amount and the estimated hydrogen use amount is greater than a predetermined threshold value.

Abstract: Disclosed are modular microbial fuel cell (MFC) devices, systems and methods for treating wastewater and generating electrical energy through a bioelectrochemical waste-to-energy conversion process. In some aspects, a modular MFC system includes a wastewater pretreatment system to receive and pre-treat raw wastewater for feeding pre-treated wastewater for bioelectrochemical processing; one or more modular MFC devices to bioelectrochemically process the pre-treated wastewater by concurrently generating electrical energy and digesting organic contaminants and particulates in the wastewater to yield treated, cleaner water; and a water collection module to receive the treated water from the one or more modular MFC devices and store the treated water and/or route the treated water from the system.

Abstract: The present specification relates to a carrier-nanoparticle complex, a catalyst including the same, an electrochemical cell or a fuel cell including the catalyst, and a method for preparing the same.

Abstract: A controlling device of a fuel cell system with multiple stack towers and a controlling method thereof are provided. The controlling device comprises a temperature sensing equipment, a processor and a pulse width modulation circuit. The fuel cell system comprises multiple fuel cell stacks. The controlling method further comprises: calculating an average temperature of the fuel cell stacks based on the temperatures of the fuel cell stacks by the temperature sensing equipment; determining whether differences between the average temperature and the temperatures of the fuel cell stacks fall within a preset range of average temperature difference by the processor, and adjusting an output current of at least one of the fuel cell stacks by the pulse width modulation circuit commanded by the processor when the difference between the average temperature and the temperature of the at least one fuel cell stack falls outside the preset range of average temperature difference.

Abstract: A fuel cell vehicle performs a control for increasing a flow rate of a cathode gas discharged to a discharge pipe when parameters including power consumption of a driving motor, a speed, and an acceleration has satisfied a flooding condition which is assumed to be satisfied in a state where a water surface reaches a discharge port in comparison with a case where the flooding condition is not satisfied. It is determined that the predetermined flooding condition has been satisfied when a state where at least three conditions, (i) the power consumption of the driving motor is equal to or greater than a predetermined first threshold value, (ii) the speed is equal to or less than a predetermined second threshold value, and (iii) the acceleration is equal to or less than a predetermined third threshold value, are satisfied is continuously maintained for a predetermined fourth threshold value or more.

Abstract: In a fuel cell system and a method of controlling the fuel cell system, correlation temperature correlated to temperature of a fuel cell stack is obtained. Further, temperature of a heating unit provided at the bottom of a water storage area of a gas liquid separator is estimated. The presence/absence of water in the gas liquid separator is determined based on the correlation temperature of the fuel cell stack and the temperature of the heating unit.

Abstract: A fuel cell system and a control method thereof are provided. In the system, an oxygen sensor is mounted on the anode inlet side and the anode outlet side of a fuel cell stack to measure an oxygen concentration. Based on the measured oxygen concentration, a control operation is performed on the fuel cell system to reduce the oxygen concentration on the anode side. Accordingly, the irreversible deterioration of the fuel cell occurring due to the reverse voltage of the cell during driving of the fuel cell vehicle and the cathode carbon corrosion occurring due to the inflow of air during parking are effectively reduced, thereby increasing the durability of the fuel cell and the fuel cell vehicle.

Abstract: A fuel cell system for modulating an offset of a hydrogen pressure sensor is provided. The fuel cell system includes a stack with a plurality of cells and each cells includes a first electrode to which hydrogen is supplied, a second electrode to which oxygen is supplied, and a membrane electrode assembly arranged between the first and second electrodes to produce electricity by reaction between the hydrogen and the oxygen. The hydrogen pressure sensor is connected to each cell to sense a pressure of the hydrogen supplied to the first electrode. A controller that which of the cells is supplied with insufficient pressure of hydrogen and modulates the offset of the hydrogen pressure sensor connected to the cell to which the hydrogen is supplied with insufficient pressure, to then supply the hydrogen to the first electrode at an appropriate pressure.

Abstract: A fuel cell vehicle capable of generating electric power in an optimum wet state is provided. A fuel cell vehicle including a fuel cell, a radiator configured to cool a coolant which has been warmed by cooling the fuel cell and send it back to the fuel cell, a grille shutter configured to adjust a flow rate of air taken into the radiator from an air intake, a sensor configured to measure an impedance of the fuel cell, and a control unit configured to control the grille shutter to open and close. The control unit controls the grille shutter to open when a measured value of the impedance becomes greater than or equal to a predetermined threshold.

Abstract: A controller of a fuel cell system executes at least one of a first control and a second control. The first control is executed when a value of current is raised in association with an increase in flow rate ratio of cathode exhaust gas flowing into a bypass, the first control is executed by which the value of the current is raised to boost discharge pressure from a compressor and subsequently, an opening degree of a flow dividing valve is changed so as to increase the flow rate ratio of the cathode exhaust gas flowing into the bypass. The second control is executed when the value of the current is lowered in association with a reduction in the flow rate ratio of the cathode exhaust gas flowing into the bypass, the second control is executed by which the opening degree of the flow dividing valve is changed so as to reduce the flow rate ratio of the cathode exhaust gas flowing into the bypass and subsequently, the value of the current is lowered so as to lower the discharge pressure from the compressor.

Abstract: A fuel cell system includes a comparator, a signal tracking controller, a first load distribution controller, a first loop gain controller, a first adder, a first PWM controller, a first fuel cell and power converter, a second load distribution controller, a second loop gain controller, a second adder, a second PWM controller, and a second fuel cell and power converter. According to the proposed fuel cell parallel system, each fuel cell connected in parallel can have a different output voltage, but the voltage at the load side can be maintained. In addition, the power output ratio of each fuel cell can be controlled under the nominal load conditions and the load varied.

Abstract: The fuel cell system includes: a fuel cell unit including first and second fuel cells connected to each other in parallel; a supply system that supplies a reactant gas to the fuel cell unit; a required output power obtainment unit configured to obtain required output power to the fuel cell unit; a supply system control unit configured to control the supply system such that output power of the fuel cell unit is the required output power; a determination unit configured to determine whether or not a predetermined condition is satisfied; and a performance obtainment unit configured to obtain output power performance of the first fuel cell.

Abstract: A method for recovering fuel cell performance by regenerating electrode characteristics through electrode reversal in order to partially recover performance of a degraded polymer electrolyte fuel cell is provided. The method includes reversing electrodes by supplying an anode of a degraded fuel cell stack with air and supplying a cathode thereof with hydrogen and performing a pulse operation by applying current to the reversed electrodes.

Abstract: In a fuel cell system, each of an inlet sealing valve and an outlet integration valve is provided with a valve seat including a valve hole and a seat surface formed on a circumferential edge of the valve hole, a valve element formed, on its outer periphery, with a seal surface corresponding to the seat surface, and a motor to move the valve element away from the valve seat upon receipt of electric power supplied from outside. The valve seat is provided with a seal member to seal between the valve element and the valve seat during non-operation of the motor. In an inlet-side bypass passage connected to an air supply passage by detouring around the inlet sealing valve, there are arranged an inlet-side bypass passage and an inlet bypass valve.

Abstract: An air supply control method and system for a fuel cell controlling a switching frequency of an inverter at which power consumption of the air compressor becomes minimal includes: calculating a revolution per minute (RPM) of a motor of an air compressor; calculating a switching frequency of an inverter of the motor of the air compressor at which power consumption becomes minimal based on the calculated RPM of the motor; and controlling the inverter with the calculated switching frequency.

Abstract: A method for operating a fuel cell vehicle includes supplying electric power to a vehicle drive motor from at least one of a fuel cell and a battery. It is determined whether an electric potential of electric power output from the fuel cell is within a deterioration acceleration region in which the fuel cell is deteriorated due to a platinum oxidation-reduction reaction. The fuel cell is controlled in a deterioration suppressing mode when the electric potential is within the deterioration acceleration region in a state where the fuel cell and the battery supply electric power to the vehicle drive motor.

Abstract: A gas diffusion layer for a metal-air battery may include a plurality of carbon nanotube thin films that are arranged to be stacked, and the carbon nanotube thin films may include a plurality of first carbon nanotubes arranged in a predetermined direction. The gas diffusion layer for the metal-air battery may include a plurality of carbon nanotube thin films in which a plurality of carbon nanotubes are arranged such that they cross each other by a floating catalyst chemical vapor deposition (“FCCVD”) method.

Abstract: An electrochemical device includes at least one electrochemical cell, including a membrane electrode assembly and bipolar plates through which at least one discharge manifold passes, the membrane electrode assembly including an active zone and a connection zone; at least one hydrogen sensor including an anode positioned in the connection zone and including a catalyst suitable for ensuring the oxidation of the hydrogen, and a cathode opposite the anode; a voltage source; a current sensor; and a computing unit, suitable for detecting the presence of hydrogen from the measured value of the electric current.

Abstract: A fuel cell system includes a plurality of fuel cells. Each of the fuel cells may include a current bypass device that is configured to flow a current responsive to an anode potential exceeding a cathode potential to prevent carbon corrosion within the fuel cell.

Abstract: A method for power control of a fuel cell system in a vehicle is disclosed. The requested fuel cell system power by the vehicle is converted into a power request made of the fuel cell by an expected power of auxiliary drives of the fuel cell system at the requested fuel cell system power being added to the requested fuel cell system power. A media supply of the fuel cell which corresponds to the power request made of the fuel cell is requested. The electrical loading of the fuel cell with current is performed in accordance with a model of the cathode dynamics such that a control variable of the control operation is matched to the media dynamics, and the power release is performed such that the fuel cell is loaded only when the adequate media supply is ensured.

Abstract: In an electric potential difference forming step of a method of inspecting output of a fuel cell, a hydrogen gas as an anode gas is supplied to an anode, and an inert gas as a cathode gas is supplied to the cathode to generate an electric potential difference between the anode and the cathode. In a maintaining step, measurement current which is smaller than rated current of the fuel cell is applied to the anode and the cathode, and the voltage between the anode and the cathode is maintained at less than the reduction potential of the electrode catalyst. In a measurement step, in the state where the measurement current is applied to the anode and the cathode, and voltage between the anode and the cathode is maintained, the cathode gas is changed to a mixed gas, and then, output of the fuel cell is measured.

Abstract: An electrical system includes a stack (3) of electrochemical cells (5), a power converter (9) electrically connected to the stack (3), a voltage comparator (7) for comparing the voltage at the terminals of at least one group of at least one electrochemical cell (5) of the stack (3) to a threshold voltage, and a control module (11) for controlling the converter (9). The control module (11) includes a generator (74) for generating a control instruction for controlling the converter (9) and a transmission member (76) for transmitting the control instruction to the converter (9). The voltage comparator (7) is suitable for transmitting a signal to the transmission member (76).

Abstract: An emergency power supply system for providing hydraulic power and electric power in an aircraft includes a fuel cell having an electric outlet for providing electric power, a conversion unit couplable with at least one of an AC bus and a DC bus and the electric outlet, and at least one hydraulic pump having a reconfigurable electric motor and a motor control unit and being couplable with a hydraulic system for providing hydraulic power. The conversion unit is adapted for converting a supply voltage of the electrical outlet to at least one of an AC voltage matching a predetermined voltage at the AC bus and a DC voltage matching a predetermined voltage at the DC bus. The reconfigurable electric motor is couplable with the fuel cell and the AC bus and is adapted for being operated by the supply of electric power either from the fuel cell or the AC bus.

Abstract: In a method for regulating a fuel cell stack (1), a current-voltage characteristic of the fuel cell stack is detected and evaluated to determine an operating point of the fuel cell stack, wherein a current-voltage characteristic of the fuel cell stack (1) is detected at time intervals in operation whose gradient has a minimum, a characteristic value (Rmin) for the minimum of the gradient is respectively determined from the detected current-voltage characteristic and a desired value for the operating point is determined by addition of a predefined offset value (Roffset) to the characteristic value, and wherein the fuel cell stack (1) is regulated by the desired value determined in this manner.