Abstract: A fuel cell system includes a pressure regulating valve for controlling a pressure of an anode gas, a purge valve for controlling a discharge amount of an anode off-gas, the purge valve being configured to change an opening area thereof at least on two stages, a pulsation operation control means configured to control the pressure regulating valve so that the pressure of the anode gas in a fuel cell when a load is high becomes higher than when the load is low, and so that the pressure of the anode gas is periodically increased and decreased at a predetermined load, and a purge valve control means configured to increase the opening area of the purge valve used during a descending transition operation so that the opening area becomes larger than the opening area used during other operations.

Abstract: A fuel cell system includes a pressure regulating valve configured to control a pressure of an anode gas to be supplied to a fuel cell, a buffer unit configured to store an anode off-gas discharged from the fuel cell, and a purge valve configured to control an amount to be discharged to an outside of the anode off-gas stored in the buffer unit. The pressure of the anode gas periodically increases/decreases by periodically opening/closing the pressure regulating valve. The purge valve is controlled so that a purge flow rate increases more during pressure reduction of the pulsation operation than during pressure increase in pulsation operation control.

Abstract: A fuel cell system includes a cathode gas supply unit, a cathode pressure detection unit, a fuel cell temperature detection unit configured to detect a temperature of the fuel cell, an internal resistance detection unit configured to detect an internal resistance of the fuel cell, a target cathode flow rate calculation unit configured to calculate a target cathode flow rate necessary for supply to the fuel cell based on an operating state of the fuel cell system, a cathode flow rate estimation unit configured to estimate a flow rate of the cathode gas according to the pressure of the cathode gas, the temperature of the fuel cell and the internal resistance of the fuel cell, and a cathode flow rate control unit configured to control the cathode gas supply unit based on the target cathode flow rate and the estimated flow rate of the cathode gas.

Abstract: A fuel cell system that generates power by supplying anode gas and cathode gas to a fuel cell has a control valve that controls pressure of the anode gas supplied to the fuel cell, a pulsation operation unit that causes pulsation of pressure of anode gas in the fuel cell in accordance with a predetermined pressure by controlling an opening degree of the control valve based on an operating condition of the fuel cell system, and a stagnation point determination unit that determines, based on a change in the pressure of the anode gas in the fuel cell, whether or not a stagnation point exists where an anode gas concentration is locally low in the fuel cell. When the stagnation determining unit determines that the stagnation point exists in the fuel cell, the pulsation operation unit increases the predetermined pressure in execution of a pulsation operation.

Abstract: A fuel cell system configured to generate power by supplying anode gas and cathode gas to a fuel cell includes a control valve for controlling a pressure of the anode gas to be supplied to the fuel cell, a buffer unit configured to store anode off-gas to be discharged from the fuel cell, a purge valve configured to adjust a flow rate of the anode off-gas discharged from the buffer unit, a pulsating operation unit configured to increase and vary the pressure of the anode gas downstream of the control valve according to a load of the fuel cell, and a purge unit configured to control an opening of the purge valve according to the load of the fuel cell. The purge unit increases the opening of the purge valve controlled according to the load of the fuel cell during a down transient operation in which the load of the fuel cell decreases.

Abstract: A fuel cell system and a method for controlling the same. The system and method employ a fuel cell stack that generates electrical power by electrochemical reaction of a fuel gas and an oxidant gas, a total generated electrical energy computation device that computes a value pertaining to the total generated electrical energy as the sum of the electrical energy generated by said fuel cell stack from start-up of the fuel cell system, and a residual water volume estimation device that estimates the residual water volume left in the fuel cell stack based on said value pertaining to said total generated electrical energy computed by said total generated electrical energy computation device.

Abstract: In a fuel cell system including a load and a fuel cell stack connected to the load and supplying an anode gas and a cathode gas to the fuel cell stack to generate power according to the load, the fuel cell system includes, a pressure setting unit configured to set a pressure of the anode gas higher when the load is high as compared with when the load is low, a stagnation point determination unit configured to determine, according to a state of power generation of the fuel cell stack, whether or not a nitrogen stagnation point is left in a reaction flow path within the fuel cell stack, and an operation control unit configured to performs an operation while preventing the pressure of the anode gas from being lowered when a required load is lowered in a state where the nitrogen stagnation point is left.

Abstract: A fuel cell system and method that enables warm-up power generation corresponding to the residual water volume in the fuel cell stack without using auxiliary devices for measuring the residual water volume in the fuel cell stack. A controller computes total generated electrical energy Q by integrating of the generated current detected by current sensor during the period from start-up to shutting down of the fuel cell system, and stores the result in total generated electrical energy storage part. Also, controller measures fuel cell temperature Ts at the last shutting down cycle with temperature sensor, and stores it in power generation shutting down temperature storage part.

Abstract: The fuel cell system is simplified and made more compact while providing the favorable recirculation of hydrogen-containing off-gas regardless of the increase or decrease in its flow rate. The fuel cell system is provided with: a cell unit that generates electricity by means of separating hydrogen-containing gas and oxygen-containing gas from each other while placing in flow contact to each other; and a recirculation mechanism for recirculating to the cell unit hydrogen-containing off-gas discharged from the cell unit. The fuel cell system has a flow rate determination unit that determines whether or not the hydrogen-containing gas fed to the cell unit is less than a predetermined flow rate; and a gas feeding pressure varying mechanism that cause the pressure of the hydrogen-containing gas to vary to increase and decrease when it is determined that the hydrogen-containing gas fed to the cell unit is less than the predetermined flow quantity.

Abstract: A fuel cell system and method that enables warm-up power generation corresponding to the residual water volume in the fuel cell stack without using auxiliary devices for measuring the residual water volume in the fuel cell stack. A controller computes total generated electrical energy Q by integrating of the generated current detected by current sensor during the period from start-up to shutting down of the fuel cell system, and stores the result in total generated electrical energy storage part. Also, controller measures fuel cell temperature Ts at the last shutting down cycle with temperature sensor, and stores it in power generation shutting down temperature storage part.

Abstract: A fuel cell system is provided with a plurality of cell units, a feeding channel, a bypass channel and a control unit. The cell units generate power by feeding hydrogen-containing gas an oxygen-containing gas separated from each other and then having them flow and join with each other. The feeding channel has an ejector arranged therein for refluxing exhausted hydrogen-containing gas exhausted from the cell units back to the cell units. The bypass channel has the hydrogen-containing gas flowing to the cell units bypass the ejector. The control unit includes a gas feeding pressure varying section that is programmed to make the hydrogen-containing gas flow in the bypass channel, and, at the same time, vary the pressure of the hydrogen-containing gas flowing in the feeding channel upon determining a flow rate of the hydrogen-containing gas flowing in the feeding channel is over a prescribed level.

Abstract: A fuel cell system is basically provided with a fuel cell, a pressure adjusting valve, a purge valve and an anode pressure controller. The fuel cell includes an anode that receives an anode gas and a cathode that receives a cathode gas to generate electric power corresponding to a load. The pressure adjusting valve is disposed in a supply path to adjust anode gas pressure to the anode. The purge valve is disposed in a discharging flow path to discharge an anode-off gas containing impurities from the fuel cell. The anode pressure controller is configured to control the pressure adjusting valve to perform a pulsation operation that pulsates the anode gas pressure of the fuel cell. The anode pressure controller decreases a median pressure of the pulsation operation as a wetness level of an electrolyte membrane of the fuel cell stack is determined to become higher.

Abstract: The fuel cell system is simplified and made more compact while providing the favorable recirculation of hydrogen-containing off-gas regardless of the increase or decrease in its flow rate. The fuel cell system is provided with: a cell unit that generates electricity by means of separating hydrogen-containing gas and oxygen-containing gas from each other while placing in flow contact to each other; and a recirculation mechanism for recirculating to the cell unit hydrogen-containing off-gas discharged from the cell unit. The fuel cell system has a flow rate determination unit that determines whether or not the hydrogen-containing gas fed to the cell unit is less than a predetermined flow rate; and a gas feeding pressure varying mechanism that cause the pressure of the hydrogen-containing gas to vary to increase and decrease when it is determined that the hydrogen-containing gas fed to the cell unit is less than the predetermined flow quantity.

Abstract: An anode gas non-recirculation type fuel cell system includes a fuel cell, a buffer tank for purging impurity gas included in anode off-gas from the fuel cell stack, an impurity gas concentration detector for detecting impurity gas concentration in the buffer tank, and an anode gas supply unit for supplying anode gas to the fuel cell stack. When pressure-supplying impurity gas in the fuel cell stack to the buffer tank while pulsating a supply pressure by the anode gas supply unit, an activation control is executed by changing, by the anode gas supply unit, at least one of a pulsative pressure and a pulsative cycle of anode gas supply according to impurity gas concentration in the buffer tank. According to the system, it is possible to get adequate hydrogen gas concentration in a fuel cell stack and to remove impurity at its activation.

Abstract: Conventional fuel cell systems had the problem of impurity gases flowing back from a buffer tank and a reduction in the voltages of unit cells when the supply pressure of an anode gas is caused to pulsate at startup. An operating method include setting any one of the amplitude and cycle of the pulsation of the supply pressure of the anode gas to a fuel cell stack (FS) in accordance with the permeability of a nitrogen gas from a cathode side to an anode side. The method makes it possible to suppress unnecessary pulsation of the supply pressure of the anode gas at startup, and thus to maintain the concentration of a hydrogen gas in the fuel cell stack (FS) at an optimum level while preventing degradation in the mechanical strength of a membrane electrode structure that constitutes each unit cell (FC) of the fuel cell stack (FS).

Abstract: A fuel cell system is provided with a fuel cell, a gas supply passage which supplies a reaction gas to the fuel cell, a humidifier which humidifies the reaction gas, a first gas discharge passage which leads from a first gas discharge outlet of the fuel cell through the humidifier to the outside, and a second gas discharge flow passage which leads from a second gas discharge outlet of the fuel cell to the outside. A flow rate control mechanism which controls the flow rate of discharge gas is provided in at least one of the first gas discharge passage and the second gas discharge passage. The configuration reduces the distance between the fuel cell and the humidifier to obtain a compact system structure.

Abstract: Disclosed is a fuel cell provided with a membrane electrode structure having a frame, two separators that sandwich the membrane electrode structure therebetween, and gas seals between the end portion of the frame and the end portions of respective separators, and diffuser sections for distributing a reacting gas to between the frame and respective separators. In the diffuser section on the cathode side, the frame is provided with a protruding section in contact with the separator, and in the diffuser section on the anode side, the frame and the separator are disposed by being spaced apart from each other, thereby excellently maintaining contact surface pressure between the membrane electrode structure and the separators, and preventing contact resistance from being increased.

Abstract: When a stop trigger of a fuel cell system (100) is turned on, air humidified by a humidifier (3) which air having a humidity quantity lower than a humidity quantity at a normal operation is supplied to a fuel cell stack (11). Thereby, a takeout quantity Qm of a moisture generated in the fuel cell stack (1) is increased, then, a power generation of the fuel cell stack (1) is continued for a certain time Pg. Then, the power generation is stopped, and a cathode side of the fuel cell stack (1) is purged with the air for a certain time Pp.

Abstract: A fuel cell system 100 includes: a fuel cell 1 for generating a power by causing an electrochemical reaction between an oxidant gas supplied to an oxidant electrode 34 and a fuel gas supplied to a fuel electrode 67; a fuel gas supplier HS for supplying the fuel gas to the fuel electrode 67; and a controller 40 for controlling the fuel gas supplier HS to thereby supply the fuel gas to the fuel electrode 67, the controller 40 being configured to implement a pressure change when an outlet of the fuel electrode 67 side is closed, wherein based on a first pressure change pattern for implementing the pressure change at a first pressure width API, the controller 40 periodically changes a pressure of the fuel gas at the fuel electrode 67.

Abstract: A fuel cell system and method that enables warm-up power generation corresponding to the residual water volume in the fuel cell stack without using auxiliary devices for measuring the residual water volume in the fuel cell stack. A controller computes total generated electrical energy Q by integrating of the generated current detected by current sensor during the period from start-up to shutting down of the fuel cell system, and stores the result in total generated electrical energy storage part. Also, controller measures fuel cell temperature Ts at the last shutting down cycle with temperature sensor, and stores it in power generation shutting down temperature storage part.