The present invention provides a relative humidity and condensed water estimator for a fuel cell and a method for controlling condensed water drain using the same. Here, the relative humidity and condensed water estimator is utilized in control of the fuel cell system involving control of anode condensed water drain by outputting at least two of signals comprising air-side relative humidity, hydrogen-side relative humidity, air-side instantaneous or cumulative condensed water, hydrogen-side instantaneous or cumulative condensed water, instantaneous and cumulative condensed water of the humidifier, membrane water contents, catalyst layer oxygen partial pressure, catalyst layer hydrogen partial pressure, stack or cell voltage, air-side catalyst layer relative humidity, hydrogen-side catalyst layer relative humidity, oxygen supercharging ratio, hydrogen supercharging ratio, residual water in a stack, and residual water in a humidifier.

A fuel cell system includes a gas supply passage configured to supply one of the anode gas and the cathode gas to the fuel cell, a refrigerant supply apparatus that supplies refrigerant for cooling the fuel cell to the fuel cell, a heat exchanger that exchanges heat between the refrigerant increased in temperature by the fuel cell and the gas supplied to the gas supply passage. The fuel cell includes a component that circulates the one of the anode gas and the cathode gas discharged from the fuel cell to the fuel cell, and a warm-up control unit that controls a flow rate of the refrigerant to a predetermined flow rate for warming up the fuel cell when the fuel cell is warmed up. The fuel cell system includes a gas temperature increase control unit increases the flow rate of the refrigerant to be supplied to the heat exchanger on the basis of a temperature of the gas circulated by the component or a parameter related to the temperature when the flow rate of the refrigerant is controlled by the warm-up control unit.

A fuel cell system includes a fuel cell, an accumulator configured to store a fuel gas, a gas remaining quantity acquisition unit configured to obtain a remaining quantity of the fuel gas stored in the accumulator, and a power generation control unit. When the remaining quantity of the fuel gas stored in the accumulator is decreased to a threshold value, the power generation control unit performs switching from humid power generation control to dry power generation control.

A controller-executed method for conditioning a membrane electrode assembly (MEA) in a fuel cell for use in a fuel cell stack includes humidifying a fuel inlet to the stack to a threshold relative humidity level, and maintaining a current density and cell voltage of the fuel cell at a calibrated current density level and hold voltage level, respectively, via the controller in at least one voltage recovery stage. The recovery stage has a predetermined voltage recovery duration. The method includes measuring the cell voltage after completing the predetermined voltage recovery duration, and executing a control action with respect to the fuel cell or fuel cell stack responsive to the measured cell voltage exceeding a target voltage, including recording a diagnostic code via the controller indicative of successful conditioning of the MEA. A fuel cell system includes the fuel cell stack and controller.

A fuel cell system includes: a fuel cell stack; a fuel gas supply/exhaust unit; an oxidant gas supply/exhaust unit; and a control unit. The control unit determines whether there is a phenomenon in the fuel cell stack resulting from local power generation concentration within a plane of a membrane electrode assembly due to a water distribution. When it is determined that there is the phenomenon, the control unit controls at least one of the fuel gas supply/exhaust unit and the oxidant gas supply/exhaust unit.

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 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 system, comprising: a measurer that measures an impedance of the fuel cell; a controller that controls an operation state of the fuel cell; and an acquirer that acquires a dryness degree of the fuel cell from the measured impedance when the operation state is a first operation state, and acquires the dryness degree of the fuel cell as a wet state when the operation state is a second operation state in which a water balance is more than the first operation state.

An apparatus includes a stack voltage monitor that measures a voltage of each channel of a plurality of channels of a fuel cell stack. Each of the channel of the plurality of channels includes a predetermined number of unit cells. The stack voltage monitor calculates impedance of each of the channel from the measured voltage. The apparatus further includes a controller that diagnoses a state of the fuel cell stack based on the impedance of each of the channel.

A method for controlling a fuel cell vehicle includes acquiring a state data, deriving a mathematical voltage model by substituting the acquired state data into a voltage calculation formula, measuring a voltage of a fuel cell, approximating a mathematical voltage model to a measurement voltage and deriving the reaction area data when the mathematical voltage model approximates the measurement voltage, and controlling the system of the fuel cell vehicle based on the derived reaction area data to eliminate or prevent an over-humidification situation of the fuel cell.