A method for enriching the oxygen fed to a fuel cell cathode intake comprises receiving at the cathode intake an oxidant from the air, storing oxygen in an adsorber coupled to the cathode intake, and adding the stored oxygen from the adsorber to the oxidant at the cathode intake during high current density operation. A fuel cell system comprises a membrane, an anode on one side of the membrane, and a cathode, coupled to a blocking member, on a second side of the membrane. The cathode comprising an intake configured to allow an oxidant to flow through the cathode, and an outlet configured to discharge unreacted oxygen from the cathode, an adsorber, coupled to the blocking member, configured to store oxygen for adding to the oxidant flowing through the cathode intake during high current density operation.

The subject matter of this specification can be embodied in, among other things, a hydrogen fuel cell anode control system including a hydrogen inlet configured to receive pressurized hydrogen, a hydrogen outlet configured to be fluidically coupled to an anode manifold of a hydrogen fuel cell, a recirculation inlet configured to receive overflow hydrogen from the anode manifold, a hydrogen pressure regulator configured to receive pressurized hydrogen from the hydrogen inlet, a hydrogen recirculation module configured to mix hydrogen received from the hydrogen pressure regulator and the recirculation inlet, and provide a hydrogen mixture to the hydrogen outlet, a differential pressure measurement module configured to measure a differential pressure between the anode manifold and a cathode manifold of the hydrogen fuel cell, and a controller configured to control at least one of the hydrogen pressure regulator or the hydrogen recirculation module based on the measured differential pressure.

Provided is a method for inspecting a current leak of a fuel cell, which is provided with an anode electrode, a cathode electrode, and an electrolyte membrane sandwiched between the anode electrode and the cathode electrode, the method including: a first process in which a first voltage, which is a limit voltage of the electrolyte membrane, is applied to the fuel cell; a second process in which a second voltage, which is lower than the first voltage, is applied to the fuel cell after the first process; a third process in which a third voltage, which is lower than the second voltage, is applied to the fuel cell after the second process; and a determination process in which a value of a current flowing through the fuel cell in the third process is detected, and whether the detected current value is lower than a prescribed current value is determined.

The invention relates to a method for determining critical operating states in a fuel cell stack, consisting of single cells connected in series, wherein a low-frequency current or voltage signal is applied to the fuel cell stack, the resulting voltage or current signal is measured and the distortion factor thd is determined. According to the invention, the weighted sum of a term dependent on the membrane resistance RM and a term dependent on the distortion factor thd is used to determine an indicator THDA.sub.dryout correlating with the drying out of the fuel cell membranes of the fuel cell stack, the membrane resistance Rm being detected by impedance measurement.

A fuel cell system includes a removal treatment execution unit configured to execute an oxide layer removal treatment that removes an oxide layer generated on a catalyst of a fuel cell. The removal treatment execution unit is configured to execute the oxide layer removal treatment by adjusting a voltage of the fuel cell to be within a predetermined second voltage range lower than a predetermined first voltage range that is lower than an open-circuit voltage, when an operation of the fuel cell system shifts from a first operation, where a current value of the fuel cell is zero and the flow rate is controlled to maintain the voltage of the fuel cell within the first voltage range, to a second operation, where the current value is larger than zero and the flow rate is controlled in response to an output request to the fuel cell.

A method of shutting down a fuel cell system includes a fuel cell includes generating power via an electrochemical reaction between a fuel gas and an oxidant gas. A shutdown command is output to the fuel cell to stop generating power. The fuel cell is controlled to continue generating power during an oxygen consumption process to consume oxygen in the oxidant gas remaining in a cathode system of the fuel cell even when the shutdown command is output to the fuel cell. At least one of voltage, current, and power output from the fuel cell is detected during the oxygen consumption process. Whether an abnormality occurs during the oxygen consumption process is determined based on at least one of the voltage, the current, and the power. The fuel cell is controlled to stop generating power during the oxygen consumption process when it is determined that abnormality occurs.

A method of cleaning power cells in an array of power cells, comprising coupling at least one first power cell to second power cells in an array of power cells and causing the second power cells to drive the at least one first power cell with a voltage to clean catalyst on the at least one first power cell.

The invention relates to a method for determining critical operating states in a fuel cell stack, consisting of single cells connected in series, wherein a low-frequency current or voltage signal is applied to the fuel cell stack, the resulting voltage or current signal is measured and the distortion factor thd is determined. According to the invention, the weighted sum of a term dependent on the membrane resistance RM and a term dependent on the distortion factor thd is used to determine an indicator THDA.sub.dryout correlating with the drying out of the fuel cell membranes of the fuel cell stack, the membrane resistance Rm being detected by impedance measurement.

Systems, methods, and other embodiments associated with fuel cell power management. According to one embodiment, a fuel cell stack includes a plurality of fuel cells producing electric potentials. An electric potential of a fuel cell is measured as a fuel cell voltage. The fuel cell stack further includes a plurality of connection points including a ground, a first connection point, and a second connection point. The first connection point draws a first voltage based on combined fuel cell voltages of a first set of fuel cells of the plurality of fuel cells. The second connection point draws a second voltage based on the combined fuel cell voltages of a second set of fuel cells of the plurality of fuel cells.

A method for humidifying an air supply of a fuel cell, an air supply circuit including an injection line, an intermediate line and an evacuation line. The method includes steps for recovering recycled air, in the evacuation line, and injecting recycled air into the injection line so as to mix it with ambient air from the environment. The method additionally includes increasing the ratio of recycled air in the injection line when a power setting of the cell reduces and if the power setting is lower than a predefined power threshold, and reducing the ratio of recycled air when the power setting increases and if the power setting remains lower than the predefined threshold.