A unit cell for a fuel cell stack including an anode catalyst layer separated by a polymer electrolyte membrane from a cathode catalyst layer, a first cell end plate separated by a first gas diffusion layer from the anode catalyst layer, and a second cell end plate separated by a second gas diffusion layer from the cathode catalyst layer, wherein the first cell end plate, the second cell end plate, or both include a matrix of electrically-conducting protrusions thereof.

A redox flow battery system including a cell and a monitor cell to which a same electrolyte solution is supplied; a current measuring unit that measures a current that is input to and output from the cell; a voltage measuring unit that measures an open circuit voltage of the monitor cell; and a computing unit. The computing unit includes a first processing unit, a second processing unit, and a third processing unit. The first processing unit computes an integral value obtained by integrating a current value measured by the current measuring unit, for an amount of time corresponding to a predetermined time constant. The second processing unit computes a corrected voltage value based on a measured voltage value measured by the voltage measuring unit and the integral value. And the third processing unit calculates a first state-of-charge value of the electrolyte solution from the corrected voltage value.

In a fuel cell state determination method for determining an internal state of a fuel cell supplied with an anode gas and a cathode gas to generate electricity, a decrease of a reaction resistance value of the cathode caused by hydrogen evolution reaction generated in the cathode as the fuel cell has an oxygen deficiency state is detected, and the oxygen deficiency state is determined on the basis of detection of the decrease of the reaction resistance value.

A method for diagnosing a water-containing state of a fuel cell stack includes steps of: applying an alternating current (AC) signal having a predetermined frequency to the fuel cell stack to calculate each of an electrolyte membrane impedance, an anode impedance, and a cathode impedance from an output voltage and an output current of the fuel cell stack corresponding to the AC signal; and diagnosing the water-containing state of the fuel cell stack on the basis of the electrolyte membrane impedance, the anode impedance, and the cathode impedance.

A fuel cell system includes a controller configured to execute refreshing control for removing an oxide film on a catalyst during an operation of a fuel cell, and an impedance measurer configured to measure an impedance of the fuel cell during the operation of the fuel cell. The impedance measurer executes a calculation process for calculating the impedance by using measurement values of a current and a voltage of the fuel cell in a predetermined measurement time, and outputs a substitute value prepared in advance as the impedance when the start of the refreshing control during the measurement time is detected.

A device for detecting a current leakage and a current leakage detection system including the same are provided. The device for detecting a current leakage includes a magnetic core having an internal space and both ends the core are separated from each other. An electric wiring extends to pass through the internal space of the magnetic core, and is connected between a power source and an electric load to supply power from the power source to the electric load. A hall sensor senses a magnetic field induced in the magnetic core.

A method and system for diagnosing a state of fuel cell are provided. The system includes a signal measurement unit that has a high pass filter with a predetermined cut-off frequency and a voltage measurement circuit, and that measures a first AC voltage to measure the fuel cell state diagnosis signal and a noise measurement unit including a band pass filter that has a predetermined pass band and a voltage measurement circuit, and that measures a second AC voltage to measure the fuel cell state diagnosis noise. A controller calculates a signal to noise ratio (SNR) of fuel cell state diagnosis data based on the first and second AC voltages, determines the corresponding fuel cell state diagnosis data to be reliable when the SNR value is greater than a predetermined reference value, and applies the fuel cell state diagnosis data to a control of a fuel cell vehicle.

A fuel cell system, including: an electric power generation control unit; an insulation-resistance measurement signal generation unit configured to generate a voltage-divided AC signal obtained by dividing an amplitude of a measurement AC signal; and an insulation resistance measurement unit configured to measure a resistance value of the insulation resistance, in which when the insulation resistance measurement unit detects, in a state where a voltage is maintained during an intermittent operation of the electric power generation control unit, an excessive noise state indicating a change in which a range of fluctuations of the peak value of the voltage-divided AC signal exceeds a predetermined allowable range of fluctuations, the insulation resistance measurement unit instructs the electric power generation control unit to change a fluctuation frequency of an output voltage of the fuel cell from a current frequency and then measures the resistance value of the insulation resistance.

An electrochemical fuel cell assembly comprises a fuel cell stack having a fuel delivery inlet and a fuel delivery outlet. The fuel cell stack further includes a number of fuel cells each having a membrane-electrode assembly and a fluid flow path coupled between the fuel delivery inlet and the fuel delivery outlet for delivery of fuel to the membrane electrode assembly. A fuel delivery conduit is coupled to the fuel delivery inlet for 10 delivery of fluid fuel to the stack. A bleed conduit is coupled to the fuel delivery outlet for venting fluid out of the stack. A variable orifice flow control device coupled to the bleed conduit configured to dynamically vary an amount of fluid from the fuel delivery outlet passing into the bleed conduit as a function of one or more of the control parameters: (i) measured fuel concentration; (ii) measured humidity; (iii) cell voltages of fuel cells in the 15 stack; (iv) impedance of fuel cells in the stack; (v) resistance of fuel cells in the stack. The variable orifice flow control device may be coupled to a recirculation conduit and may be configured to dynamically vary a proportion of fluid from the fuel delivery outlet passing into the bleed conduit as a function of the control parameters.

A method of predicting a life of a membrane electrode assembly (MEA) of a fuel cell for electric power generation includes: deriving an operating condition for accelerated degradation, which is applicable to the fuel cell; operating the fuel cell for a specific time under the derived operating condition for accelerated degradation and under a normal operating condition, and identifying the degree of degradation of the fuel cell under each of the operating conditions; calculating an acceleration multiple based on the degree of degradation identified under the operating condition for accelerated degradation and under the normal operating condition; and predicting the life of the membrane electrode assembly based on the acceleration multiple.