Provided is a method of operating a fuel cell system equipped with a fuel cell stack, a liquid hydrogen storage unit configured to store liquid hydrogen, a boil-off gas recovery unit configured to recover boil-off gas generated from the liquid hydrogen storage unit, and a hydrogen concentration estimation unit configured to estimate the hydrogen concentration at a hydrogen electrode in the fuel cell stack in a standby state, the method including: in a case in which a hydrogen concentration at a hydrogen electrode in the fuel cell stack in a standby state has become less than a predetermined value, supplying boil-off gas recovered by the boil-off gas recovery unit to the hydrogen electrode in the fuel cell stack.

The invention relates to a fuel cell system comprising a stack of electrochemical cells forming a polymer ion-exchange membrane fuel cell (6), a fuel gas supply circuit and an oxidant gas supply circuit.

Said oxidant gas supply circuit comprises a compressor (3) intended to compress the ambient air before it enters the fuel cell (6), and an outlet exhaust (10) intended to discharge the gases leaving the fuel cell.

Said supply circuit is connected to the fuel cell at a first access point (7) and a second access point (8).

The system additionally comprises a switching element (11) that has two positions: a first position in which the outlet of the compressor (3) is connected to the first access point (7), and the second access point (8) is connected to the outlet exhaust (10), and a second position in which the outlet of the compressor (3) is connected to the second access point (8), and the first access point (7) is connected to the outlet exhaust (10).

The system is characterized in that it contains a moisture reservoir positioned in the oxidant gas supply circuit, upstream of the first access point (7).

The present invention is a hydrogen exhaust device for fuel cell. A tail gas discharge device for a fuel cell system includes a steam trap, a buffer solenoid valve, a buffer tank and a drain solenoid valve. The steam trap can collect water from wet hydrogen. The buffer tank is a hollow cavity structure such as a tank. Preferably, the steam trap has an upper cover, a main body, a lower cover and a filter. The upper cover has a wet hydrogen inlet, a pressure sensor, a dry hydrogen outlet and a temperature sensor. The lower cover has a liquid storage cavity and a filter support part. The filter has a filter filler and a filter intake channel.

A method of operating a fuel cell system which includes a plurality of fuel cells and a plurality of auxiliary components located in at least one cabinet, includes monitoring, by a control unit, a parameter of the fuel cell system, determining whether the parameter has violated a threshold, and varying an auxiliary bus voltage provided to the plurality of auxiliary components connected to a common auxiliary bus by a first amount in response to determining that the parameter has violated the threshold.

A fuel cell system including a fuel cell stack having cathode and anode sides, a housing surrounding the fuel cell stack, a housing purging air inlet, an air-conveying installation disposed on the housing purging air inlet, a housing purging air outlet, an oxidation catalyst, a temperature sensor, and a control unit. The air-conveying installation continuously directs an airflow into the housing purging air inlet. The oxidation catalyst is disposed downstream of the housing purging air outlet and catalytically combusts hydrogen and oxygen. The temperature sensor is disposed on the oxidation catalyst and detects the oxidation catalyst temperature as an information item pertaining to a volumetric hydrogen flow occurring outside a fuel cell process and to be discharged. The control unit couples to the temperature sensor and to the air-conveying installation and receives the temperature detected by the temperature sensor and to therefrom determine variations of a hydrogen concentration.

A fuel cell system includes a first fuel cell having first unit cells stacked together, a second fuel cell having second unit cells stacked together, a first voltage detector, a second voltage detector, and a controller. The first voltage detector detects voltage of the first unit cells for every “N” unit cells on average, and the second voltage detector detects voltage of the whole second fuel cell, or detects voltage of the second unit cells for every “M” unit cells on average. The controller determines whether any of the first unit cells is in a fuel deficiency state, by referring to a detection result of the first voltage detector, and performs a cancellation process to cancel the fuel deficiency state, on the first fuel cell that is in a power generating state, while stopping power generation of the second fuel cell, when an affirmative decision is obtained.

A method comprising feeding a fuel and an oxidant to individual cells in a fuel cell stack, each having two electrode layers and an electrolyte layer arranged between the electrode layers. The method further includes compressing the cell stack with a clamping device, and detecting a compression pressure upon the cell stack with at least one pressure sensor. The method also includes determining a moisture content of the two electrolyte layers based on the detected compression pressure.

A system and method for controlling a start of a fuel cell vehicle are provided. The method includes supplying hydrogen and air to a fuel cell and operating a converter so that a voltage on a high-voltage bus is constant, wherein the converter is disposed between a high-voltage battery and the high-voltage bus which is connected to an output terminal of the fuel cell. The voltage on the high-voltage bus is maintained at a preset lowest control voltage and the voltage on the high-voltage bus is adjusted based on a result comparing a preset lower-limit operational voltage of an inverter with an inverter detection voltage. The inverter is disposed between the high-voltage bus and a drive motor, and the inverter detection voltage is detected on a terminal of the inverter which is connected to the high-voltage bus.

A method and apparatus for operating an intermediate-temperature solid-oxide fuel cell stack (10) with a mixed ionic/electronic conducting electrolyte in order to increase its efficiency. The required power output of the solid-oxide fuel cell stack (10) is determined and one or more operating conditions of the solid fuel cell stack (10) are controlled dependent upon the determined required power output. The operating conditions that are controlled may be at least one or the temperature of the fuel cell stack and the dilution of fuel delivered to the fuel cell stack.

An object is to provide a technique that a current state of a fuel cell may be detected more accurately. A fuel cell system includes a controller, a fuel cell, and an impedance measurer that may measure an impedance of the fuel cell. The controller obtains a first impedance value that expresses the impedance of the fuel cell in a predetermined state, acquires a second impedance value that expresses the impedance of the fuel cell that is measured by the impedance measurer during operation control of the fuel cell, and performs operation control of the fuel cell using the first impedance value and the second impedance value.