A state determination device for a fuel cell for generating power upon receiving the supply of anode gas and cathode gas, comprising: an internal impedance measurement unit configured to measure an internal impedance of the fuel cell on the basis of an alternating-current signal of a predetermined frequency output from the fuel cell; and an anode reaction resistance estimation/calculation unit configured to calculate an estimation value of a reaction resistance of an anode electrode of the fuel cell on the basis of a measurement value of the internal impedance, wherein: the predetermined frequency is selected such that a difference between the estimation value of the reaction resistance of the anode electrode during hydrogen starvation and the estimation value of the reaction resistance of the anode electrode during oxygen starvation is not smaller than a predetermined value.

A fuel cell has an electrolyte membrane of 5 to 10 μm in thickness. A control device for this fuel cell comprises: a controller configured to control an amount of power generation by the fuel cell according to a required amount of electric power; and a power generation reducer configured to reduce the amount of power generation by the fuel cell at a humidity of an electrolyte membrane of 95 to 98% RH to be lower than the amount of power generation at the humidity of the electrolyte membrane of lower than 95% RH.

A driving control method and system of a fuel cell system are provided. The method includes determining, by a controller, a dry state of a fuel cell stack and stopping an air blower, which supplies air to the fuel cell stack, using different processes based on whether the fuel cell stack is in the dry state. Accordingly, the time for which an open circuit voltage (OCV) is maintained is reduced and durability of the fuel cell is improved by preventing dry-out of the fuel cell stack.

A fuel cell control method and are provided. The method includes collecting state data of a fuel cell stack and then estimating an effective catalytic amount of the fuel cell stack based on the collected state data. A fuel cell system is operated based on the estimated effective catalytic amount to thus optimize the efficiency of the system.

A fuel cell system that includes a fuel cell body that is formed by a membrane electrode assembly including an anode catalyst and a cathode catalyst between which an electrolyte membrane is sandwiched and a pair of separators forming an anode-catalyst-side flow channel and a cathode-catalyst-side flow channel, a fuel supply system configured to supply fuel gas to the fuel cell body, an oxidant supply system configured to supply oxidant gas to the fuel cell body, a control device that controls these supply systems in accordance with an operating state of the fuel cell system and a catalyst deterioration recovery device that recovers deterioration of the anode catalyst. The catalyst deterioration recovery device includes a plurality of catalyst deterioration recovery means, a specific operating state detecting means configured to detect a specific operating state of the fuel cell system and a selecting means configured to selectively activate the plurality of catalyst deterioration recovery means in accordance with the specific operating state.

A method of examining a fuel cell by means of a cyclic voltammetry analysis, wherein the cyclic voltammetry analysis is used to ascertain a gas composition in the fuel cell. The fuel cell has a first gas space for a first reactant and a second gas space for a second reactant, where no reactant is supplied at least to one of the two gas spaces, especially to either gas space, during the cyclic voltammetry analysis. The cyclic voltammetry analysis is used to ascertain a concentration of hydrogen in the gas spaces.

A system and method for controlling operation of a fuel cell are provided. The method includes estimating an effective catalyst amount within a fuel cell stack and monitoring a change in the estimated effective catalyst amount according to time. An irreversible degradation state of the fuel cell stack is determined based on the monitored change in the estimated effective catalyst amount.

The fuel cell system determines whether or not condensation is occurring in the anode gas and the cathode gas on the basis of the humidity of the cathode gas detected by a first humidity sensor provided in the power generation cells and the humidity of the anode gas detected by a second humidity sensor provided in the power generation cells, and adjusts the water content in the cathode gas and/or the anode gas in which condensation is occurring.

A fuel cell system includes a cathode system device, an anode system device, an ion detector, and a controller. When the concentration of fluoride ions exceeds a predetermined concentration threshold, the controller controls at least one of the cathode system device and the anode system device to adjust a load applied to the membrane electrode assemblies.

A method of examining a fuel cell by means of a cyclic voltammetry analysis, wherein the cyclic voltammetry analysis is used to ascertain a gas composition in the fuel cell. The fuel cell has a first gas space for a first reactant and a second gas space for a second reactant, where no reactant is supplied at least to one of the two gas spaces, especially to either gas space, during the cyclic voltammetry analysis. The cyclic voltammetry analysis is used to ascertain a concentration of hydrogen in the gas spaces.