A fuel cell system includes a fuel cell that generates electricity by causing reaction of a fuel component contained in fuel gas, a supply path, a control valve, an ejector, a return path, and a controller. The control valve is provided on the supply path. The ejector is provided in a section on the supply path between the control valve and the fuel cell. The return path is connected between an exhaust port of the fuel cell and the ejector, and returns off-gas discharged from the exhaust port to the supply path by suction force generated by the ejector. The controller selectively executes a normal operation and a particular operation. In the particular operation, the control valve is continuously or intermittently opened to a second opening degree smaller than a first opening degree, when the fuel gas is supplied to the fuel cell at a first supply amount.

A fuel cell system includes a fuel cell stack, a fuel gas supply path, an injector, an ejector, a circulation path, a pressure difference detection unit that detects a pressure difference between an ejector inlet port pressure and an ejector outlet port pressure, and a control device. The control device calculates a required circulation flow rate that is required for a fuel off gas supplied from the fuel cell stack to the ejector, based on a required load for the fuel cell stack, calculates an estimated circulation flow rate that is an estimated flow rate of the fuel off gas supplied from the fuel cell stack to the ejector, based on the required load and the pressure difference, and increases the flow rate of a fuel gas supplied from the injector to the fuel cell stack when the estimated circulation flow rate is lower than the required circulation flow rate.

A fuel cell system includes a fuel cell stack, a fuel gas supply path, an injector, an ejector, a circulation path, a pressure difference detection unit that detects a pressure difference between an ejector inlet port pressure and an ejector outlet port pressure, and a control device. The control device calculates a required circulation flow rate that is required for a fuel off gas supplied from the fuel cell stack to the ejector, based on a required load for the fuel cell stack, calculates an estimated circulation flow rate that is an estimated flow rate of the fuel off gas supplied from the fuel cell stack to the ejector, based on the required load and the pressure difference, and increases the flow rate of a fuel gas supplied from the injector to the fuel cell stack when the estimated circulation flow rate is lower than the required circulation flow rate.

A hydrogen supply system that supplies hydrogen gas to a fuel cell and causes the fuel cell to generate electricity includes a plurality of hydrogen tanks that each store hydrogen gas, and a hydrogen gas supply path that supplies the hydrogen gas to the fuel cell from each of the plurality of hydrogen tanks. At least one hydrogen tank of the plurality of hydrogen tanks is a first reserve tank that is connected to a hydrogen gas collecting pipe or a hydrogen gas recovery pipe, and that stores hydrogen gas that was not used in generating electricity in the fuel cell.

A fuel cell system includes a hydrogen tank to store hydrogen, a fuel cell to receive hydrogen gas from the hydrogen tank to generate electricity, a temperature controller to adjust a temperature inside the hydrogen tank, and a control unit to control the temperature controller based on the amount of hydrogen remaining in the hydrogen tank, the control unit being configured to increase the temperature inside the hydrogen tank when the amount of the remaining hydrogen is equal to or less than a first predetermined value.

A fuel cell system and a method for controlling the same may adjust generation of condensate water in a fuel cell by setting relative humidities and temperature and pressure conditions of the fuel cell so as to maintain a constant current density, and may alleviate performance deterioration of the fuel cell during operation by removing an excessive amount of the generated condensate water by injecting a cathode pressure impulse into the fuel cell.

A fuel cell system and a method for controlling the same may adjust generation of condensate water in a fuel cell by setting relative humidities and temperature and pressure conditions of the fuel cell so as to maintain a constant current density, and may alleviate performance deterioration of the fuel cell during operation by removing an excessive amount of the generated condensate water by injecting a cathode pressure impulse into the fuel cell.

A method for operating a fuel cell system having a fuel cell stack includes detecting a failure of a first cooling fan that blows exterior air to a first radiator, opening a first valve such that first cooling water that passes via the fuel cell stack flows toward the fuel cell stack, controlling an RPM of a blower of an air conditioning system to a maximum level, controlling an opening degree of a second valve according to a cooling degree of the first radiator and a cooling degree of the air conditioning system, and controlling an RPM of a first pump that pumps the first cooling water to a maximum level.

A fuel cell system installed in a vehicle, the system comprising: a fuel cell, a secondary cell, a temperature acquirer for acquiring a temperature of the fuel cell, a state-of-charge value acquirer for acquiring a state-of-charge-value of the secondary cell, an outside temperature acquirer for acquiring an outside temperature, an outside pressure acquirer for acquiring an outside pressure, and a controller for controlling power of the secondary cell, wherein, when the temperature of the fuel cell exceeds a predetermined temperature, when the state-of-charge value of the secondary cell is a predetermined threshold value or more, when the outside temperature is a predetermined temperature or more, and when the outside pressure is a predetermined pressure or less, the controller increases the power of the secondary cell larger than power required of the secondary cell for normal running of the vehicle.

An incorporated air supplying apparatus for a fuel cell stack and a method for controlling an air flow using the same are described. The apparatus includes an air supply part supplying air to a plurality of fuel cell stacks, a plurality of pipes configured to transmit the air supplied from the air supply part to each of the fuel cell stacks, a flowmeter and a valve installed at each pipe, and a controller controlling an opening degree of each of the valves, based on information on the measured flow. The controller controls the opening degree of the valve installed at each pipe, thus enabling the air flow for each pipe to be controlled.