A system and methods for managing water content in one or more electrochemical cell is disclosed. The system includes a gas-phase conduit for receiving humid gas-phase associated with the electrochemical cell, a desiccator unit connected to each electrochemical cell and configured for extracting water from the humid gas-phase, a heater for selectively heating the desiccator unit, and a carbon dioxide (CO2) scrubber connected to the desiccator unit. The system may capture water vapor at the desiccator unit from a humid gas-phase exiting electrochemical cell, or release water vapor in desiccator unit, via actuation of heater, that is transported into the electrochemical cell depending on the mode of operation. The CO2 scrubber may also be used to capture water vapor, based on the mode of operation.

A fuel cell internal state detection system includes estimation object state quantity setting unit for setting a suitable estimation object state quantity as an index of an internal state, an impedance value acquisition unit configured to obtain an impedance value of a fuel cell, an impedance usability judging unit configured to judge whether or not the obtained impedance value is usable for the calculation of the estimation object state quantity, estimation object state quantity calculation unit for calculating the estimation object state quantity set by the estimation object state quantity setting unit on the basis of the obtained impedance value when the impedance value is judged to be usable for the calculation of the estimation object state quantity by the impedance usability judging unit, and an unusable-scene process execution unit configured to perform an unusable-scene process when the impedance value is judged not to be usable for the calculation of the estimation object state quantity by the impedance usability judging unit.

A fuel cell system includes: a wetness target value calculating unit configured to calculate a target value of a wet state of the fuel cell; a gas required flow rate calculating unit configured to calculate a cathode gas required flow rate on the basis of a power generation request to the fuel cell; a wetness-control anode gas flow rate calculating unit configured to calculate a wetness-control anode gas circulation flow rate at least on the basis of the wetness target value and the cathode gas required flow rate during a dry control; an anode gas flow rate control unit configured to control an anode gas circulation flow rate on the basis of the wetness-control anode gas circulation flow rate; a wetness-control cathode gas flow rate calculating unit configured to calculate a wetness-control cathode gas flow rate at least on the basis of the wetness target value and a measured value or estimated value of the anode gas circulation flow rate during the dry control; and a cathode gas flow rate control unit configured to control a cathode gas flow rate on the basis of the cathode gas required flow rate and the wetness-control cathode gas flow rate.

A control method for fuel cell system capable of executing an idle stop operation is provided, in which operation power generation of a fuel cell is selectively stopped according to a required output of a load and cathode gas is intermittently supplied to the fuel cell during an operation stop. An upper limit value and a lower limit value of an output voltage of the fuel cell during the idle stop operation is set, the cathode gas is intermittently supplied with the output voltage of the fuel cell set at a value between the upper limit value and the lower limit value, a wet/dry state of the fuel cell is detected, a wet/dry appropriate range in which the wet/dry state of the fuel cell during the idle stop operation is appropriate is set, and it is determined whether or not the detected wet/dry state of the fuel cell is within the set wet/dry appropriate range. If the wet/dry state of the fuel cell is determined to be outside the set wet/dry appropriate range, the output voltage of the fuel cell is reset, and the cathode gas is intermittently supplied with the output voltage of the fuel cell set at a value between the upper limit value and lower limit value of the reset output voltage.

A fuel cell system includes a compressor, a relief valve that adjusts a pressure of a cathode gas, a pulsation operation unit that pulsates an anode gas pressure, a target flow rate setting unit that sets a target flow rate of the cathode gas, a first target pressure setting unit that sets a first target pressure of the cathode gas, a second target pressure setting unit that sets a second target pressure of the cathode gas for maintaining a pressure difference between an anode and a cathode within a predetermined allowable range, a target pressure setting unit that sets the higher one of the first and second target pressures as a target pressure, and a control unit that controls the compressor on the basis of the target flow rate and a limitative pressure obtained by limiting pulsation of the target pressure.

A state detection device for fuel cell includes a supposed high-frequency impedance value setting unit configured to set a supposed high-frequency impedance value on the basis of an impedance measurement value belonging to an arc region of an impedance curve of the fuel cell, an actually measured high-frequency impedance value calculation unit configured to obtain an actually measured high-frequency impedance value on the basis of an impedance measurement value belonging to a non-arc region of the impedance curve of the fuel cell, and an ionomer resistance estimation unit configured to estimate a value obtained by subtracting the actually measured high-frequency impedance value from the supposed high-frequency impedance value as an ionomer resistance value. The supposed high-frequency impedance value setting unit sets a value of an intersection of an equivalent circuit impedance curve set on the basis of the impedance measurement value belonging to the arc region and a real ads as the supposed high-frequency impedance value.

A method for activating a fuel cell stack without using an electric load includes chemically adsorbing hydrogen into a catalyst of a cathode. Oxygen remaining in the stack is removed to seal and store the fuel cell stack while maintaining a negative pressure in the fuel cell stack. The method for activating a fuel cell stack does not require an electric load device, and therefore does not increase the number of activation equipment, thereby preventing the total production speed of the fuel cell stack from reducing in response to the stack activation.

A system includes a fuel cell stack (FCS) and a controller. The controller is configured to, in response to a stack current request corresponding to a stack current of the FCS which would cause a membrane hydration level of the FCS to be outside of a desired hydration range, adjust the stack current request to correspond to an adjusted stack current of the FCS which causes the membrane hydration level to be maintained within the desired hydration range.

A fuel cell module has a hydrogen recirculation pump and a controller. The controller receives a signal indicating the response of the pump to changes in the density or humidity of gasses in the hydrogen recirculation loop. The controller is programmed to consider the signal in controlling one or more balance of plant elements that effect the removal of water from the stack. In a process for operating the fuel cell module, the signal is considered when controlling one or more balance of plant elements that effect the removal of water from the stack. For example, an increase in current drawn from a constant speed or voltage recirculation pump indicates an increase in humidity and suggests that water should be removed from the stack, for example by increasing a coolant temperature set point.

An apparatus and a method for controlling a humidification amount of a membrane humidifier for a fuel cell are provided. The humidification amount of the membrane humidifier relative to air supplied to a stack is changed by adjusting a difference in partial pressure of moisture between the inside and the exterior of a hollow fiber membrane that constitutes the membrane humidifier for a fuel cell.