Abstract: A fuel cell system includes: a fuel cell which generates electricity by supplying hydrogen to an anode electrode, and a reaction gas to a cathode electrode, an anode gas supply device which supplies hydrogen to the anode electrode, and a cathode gas supply device which drives a compressor using electric power generated by the fuel cell, and supplies pressurized reaction gas to the cathode electrode. The fuel cell system further includes a target pressure setting device which sets a target value for cathode pressure of the fuel cell, a correction device which corrects the target value in accordance with atmospheric pressure, and a control device which controls the cathode pressure of the fuel cell to the corrected target value. Efficient electric power generation can be performed in accordance with the ambient environment.

Abstract: An oxidizing agent supply system failure determination method for a fuel cell for use with a fuel cell apparatus provided with a fuel cell that is supplied with a fuel and an oxidizing agent, and an oxidizing agent supply system that has an oxidizing agent condition adjusting means that adjusts condition of the oxidizing agent supplied to the fuel cell, comprising the step of determining that the oxidizing agent supply system has failed if an absolute value of a difference between an actual value of a supply provided by the oxidizing agent condition adjusting means and a first predetermined value that is compared to the actual value is equal to or greater than a second predetermined value and a predetermined period of time has passed. An oxidizing agent supply system failure determination method for a fuel cell is provided which can maintain the reliability of the fuel cell apparatus.

Abstract: A fuel cell system includes: a fuel cell in which electrical power generation is performed through chemical reactions of reaction gases being supplied thereto; a discharge path through which the reaction gases are discharged; a discharge valve provided on the discharge path and operated for discharging the reaction gases through the discharge path; an opening condition monitoring device for continuously monitoring a demanded opening condition of the discharge valve; and an opening condition renewing device for renewing the demanded opening condition of the discharge valve depending on the demanded opening condition of the discharge valve detected by the opening condition monitoring device when opening of the discharge valve is demanded. Opening of the discharge valve is controlled depending on the latest demanded opening condition which has been renewed by the opening condition renewing device.

Abstract: A control device for a fuel cell including a transient state determination unit which determines whether changes in generated output of the fuel cell are within a predetermined range; a hydrogen purge detection unit which detects the presence/absence of a purge command to a hydrogen purge valve; a failure determination unit which determines, if the transient state determination unit determined that it is not a transient state, failure in the hydrogen purge valve based on an actual hydrogen pressure value at an inlet portion of the fuel cell and a target hydrogen pressure value, which is set in accordance with the presence/absence of the purge command detected by the hydrogen purge detection unit; and an alarm unit which generates an alarm when failure in the hydrogen purge valve is determined by the failure determination unit.

Abstract: A start-up method for a fuel cell system that includes a fuel cell that carries out power generation by the electrochemical reaction between a fuel gas and the oxygen gas in the air; a fuel gas discharge path and a fuel gas supply path that are connected to the fuel cell; a fuel gas circulation path in which the fuel gas discharge path merges with the fuel gas supply path; and a purge valve provided on the fuel gas circulation path in order to discharge the circulating fuel gas from the fuel gas circulation path. The method includes the steps of opening the purge valve at the same time that the fuel gas is supplied to the fuel cell and replacing the nitrogen gas that originates in the air and is present in the fuel gas circulation path by fuel gas; and closing the purge valve after the nitrogen gas in the fuel gas circulation path has been replaced by the fuel gas.

Abstract: A method for controlling the flow rate of an oxidizer in a fuel cell system having a fuel cell stack being supplied with fuel and the oxidizer, a compressor for supplying the oxidizer to the fuel cell stack, a back pressure valve for controlling pressure of the oxidizer, and a control device for controlling the fuel cell stack, the compressor, and the back pressure valve. The method includes the steps of calculating an oxidizer pressure command and an oxidizer flow rate command based on a given electrical current command, comparing a first flow rate that is defined as an upper limit of oxidizer flow rate and a second flow rate that is defined as a lower limit of oxidizer flow rate with the oxidizer flow rate command, and regulating the oxidizer flow rate command so as to be limited within a range from the second flow rate to the first flow rate.

Abstract: A function maintaining method for fuel cell system, the fuel cell system including a fuel cell that is supplied fuel and an oxidant to generate electricity, a fuel tank that supplies the fuel to the fuel cell, a tank pressure sensor that detects the pressure of the fuel tank, and a control apparatus that controls the same. The function maintaining method comprises calculating, when a failure of the tank pressure sensor has been detected, the pressure of the tank before a predetermined time interval from the time of this detection and a fuel consumption amount and fuel discharge amount after the detection of the failure, and estimation the pressure of the tank by using the same. A fuel cell system is obtained which can maintain the function and reliability of the fuel cell system.

Abstract: A function maintaining method for fuel cell system, the fuel cell system including a fuel cell that is supplied fuel and an oxidant to generate electricity, a fuel tank that supplies the fuel to the fuel cell, a tank pressure sensor that detects the pressure of the fuel tank, and a control apparatus that controls the same. The function maintaining method comprises calculating, when a failure of the tank pressure sensor has been detected, the pressure of the tank before a predetermined time interval from the time of this detection and a fuel consumption amount and fuel discharge amount after the detection of the failure, and estimation the pressure of the tank by using the same. A fuel cell system is obtained which can maintain the function and reliability of the fuel cell system.

Abstract: An oxidizing agent supply system failure determination method for a fuel cell for use with a fuel cell apparatus provided with a fuel cell that is supplied with a fuel and an oxidizing agent, and an oxidizing agent supply system that has an oxidizing agent condition adjusting means that adjusts condition of the oxidizing agent supplied to the fuel cell, comprising the step of determining that the oxidizing agent supply system has failed if an absolute value of a difference between an actual value of a supply provided by the oxidizing agent condition adjusting means and a first predetermined value that is compared to the actual value is equal to or greater than a second predetermined value and a predetermined period of time has passed. An oxidizing agent supply system failure determination method for a fuel cell is provided which can maintain the reliability of the fuel cell apparatus.

Abstract: A method for controlling the flow rate of an oxidizer in a fuel cell system having a fuel cell stack being supplied with fuel and the oxidizer, a compressor for supplying the oxidizer to the fuel cell stack, a back pressure valve for controlling pressure of the oxidizer, and a control device for controlling the fuel cell stack, the compressor, and the back pressure valve. The method includes the steps of calculating an oxidizer pressure command and an oxidizer flow rate command based on a given electrical current command, comparing a first flow rate that is defined as an upper limit of oxidizer flow rate and a second flow rate that is defined as a lower limit of oxidizer flow rate with the oxidizer flow rate command, and regulating the oxidizer flow rate command so as to be limited within a range from the second flow rate to the first flow rate.

Abstract: A fuel cell system comprises a fuel cell, a hydrogen discharge valve for discharging hydrogen from the fuel cell under a predetermined condition, a hydrogen concentration reduction device for reducing the concentration of hydrogen discharged from the hydrogen discharge valve, a hydrogen sensor for detecting an instantaneous hydrogen concentration of a gas processed by the hydrogen concentration reduction device and an average hydrogen concentration calculating unit for calculating an average hydrogen concentration per hour of a gas processed by the hydrogen concentration reduction device, wherein a hydrogen discharge from the fuel cell by the hydrogen discharge valve is prohibited in the event that an instantaneous hydrogen concentration detected by the hydrogen sensor exceeds a first threshold, or in the event that an average hydrogen concentration calculated by the average hydrogen concentration calculating unit exceeds a second threshold which is lower than the first threshold.

Abstract: A hydrogen purge control apparatus includes a fuel cell stack from which hydrogen is purged as necessary, a purged hydrogen dilution device which is disposed downstream of the fuel cell stack, and which has a chamber formed therein, a first inlet for purged hydrogen, a second inlet for air, and an outlet for diluted hydrogen, a regulator which is disposed between the fuel cell stack and the first inlet, and which is provided for regulating an amount of the purged hydrogen flowing into the purged hydrogen dilution device, and a control unit having a hydrogen concentration estimating section that is configured to estimate the hydrogen concentration at the outlet of the purged hydrogen dilution device based on an operating state of the fuel cell stack. The regulator is operated by the control unit depending on the hydrogen concentration estimated by the hydrogen concentration estimating section.

Abstract: A control system for a fuel cell includes a vapor generation unit, a fuel reforming unit, a fuel supply unit, a combustion unit, a fuel vapor temperature detection unit, a temperature detection unit, a current detection unit, and a control unit. The vapor generation unit produces a fuel vapor by vaporizing a liquid fuel. The fuel reforming unit reforms the fuel vapor to produce a hydrogen-enriched fuel. The fuel supply unit supplies the reformed fuel to the fuel cell. The control unit calculates quantity of heat retained by the vapor generation unit based on the temperature of the fuel vapor, the temperature of the combustion unit, and the generated current. The control unit also controls a fuel supply command value for the fuel supply unit and/or a current generation command value for the fuel cell based on the calculated quantity of heat retained by the vapor generation unit.

Abstract: A control system for a fuel cell includes a reactant gas supplying unit which supplies a reactant gas to the fuel cell, and a discharged reactant gas flow control unit disposed at an outlet of the fuel cell. The discharged reactant gas flow control unit includes a first control valve and a second control valve disposed in parallel with the first control valve. The second control valve has a different pressure-flow control characteristic as compared with the first control valve. Only the second control valve controls the flow rate of a discharged reactant gas until the flow rate exceeds a predetermined value, and the second control valve together with the first control valve controls the flow rate of the discharged reactant gas when the flow rate of the discharged reactant gas exceeds the predetermined value.

Abstract: A control device for a fuel cell including a transient state determination unit which determines whether changes in generated output of the fuel cell are within a predetermined range; a hydrogen purge detection unit which detects the presence/absence of a purge command to a hydrogen purge valve; a failure determination unit which determines, if the transient state determination unit determined that it is not a transient state, failure in the hydrogen purge valve based on an actual hydrogen pressure value at an inlet portion of the fuel cell and a target hydrogen pressure value, which is set in accordance with the presence/absence of the purge command detected by the hydrogen purge detection unit; and an alarm unit which generates an alarm when failure in the hydrogen purge valve is determined by the failure determination unit.

Abstract: A control system for a fuel cell includes a vapor generation unit, a fuel reforming unit, a fuel supply unit, a combustion unit, a fuel vapor temperature detection unit, a temperature detection unit, a current detection unit, and a control unit. The vapor generation unit produces a fuel vapor by vaporizing a liquid fuel. The fuel reforming unit reforms the fuel vapor to produce a hydrogen-enriched fuel. The fuel supply unit supplies the reformed fuel to the fuel cell. The control unit calculates quantity of heat retained by the vapor generation unit based on the temperature of the fuel vapor, the temperature of the combustion unit, and the generated current. The control unit also controls a fuel supply command value for the fuel supply unit and/or a current generation command value for the fuel cell based on the calculated quantity of heat retained by the vapor generation unit.

Abstract: A control system for a fuel cell includes a reactant gas supplying unit which supplies a reactant gas to the fuel cell, and a discharged reactant gas flow control unit disposed at an outlet of the fuel cell. The discharged reactant gas flow control unit includes a first control valve and a second control valve disposed in parallel with the first control valve. The second control valve has a different pressure-flow control characteristic as compared with the first control valve. Only the second control valve controls the flow rate of a discharged reactant gas until the flow rate exceeds a predetermined value, and the second control valve together with the first control valve controls the flow rate of the discharged reactant gas when the flow rate of the discharged reactant gas exceeds the predetermined value.