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.

Disclosed are a redox flow battery and a method of measuring a state of charge (SOC) thereof. The method may include measuring an open circuit voltage (OCV) during a specific period of time when a charging or discharging operation of a redox flow battery is performed, analyzing a change in SOC of the redox flow battery based on the measured OCV, correcting Coulomb efficiency based on the change in SOC, and calculating a second SOC of the redox flow battery based on the corrected Coulomb efficiency. The Coulomb efficiency may be a parameter, in which information regarding actual operation factors of the redox flow battery is contained.

An AC component I addition unit of a diagnostic device superimposes an alternating current on an output current of a fuel cell. A Zn calculation unit calculates a cell impedance with respect to the alternating current with regard to any of a plurality of cells. A diagnosis unit diagnoses that any cell is subjected to hydrogen deficiency when an absolute value of the cell impedance exceeds (absolute value of a reference impedance+a predetermined value ). It is diagnosed that any cell is subjected to oxygen deficiency when the absolute value of the cell impedance is smaller than (absolute value of the reference impedancea predetermined value ).

In a fuel cell system, a preceding-stage fuel cell and a following-stage fuel cell are connected via a fuel flow path. The fuel cell system includes a reformer that supplies reformed gas to the preceding-stage fuel cell; an acquisition unit that acquires the amount of heat generation and the amount of heat absorption of the preceding-stage fuel cell; and a control unit that controls at least one of the amount of current of the preceding-stage fuel cell, the flow rate of air to be supplied to the reformer, and the temperature of the preceding-stage fuel cell if the amount of heat absorption acquired by the acquisition unit is larger than the amount of heat generation acquired by the acquisition unit.

Method for regenerating a fuel cell comprising the following steps in succession: providing a fuel cell comprising: an anodic chamber (1) equipped with a dihydrogen inlet (4), a dihydrogen outlet (5), and at least one anode (6); a cathodic chamber (2) equipped with a gas inlet (7), a gas outlet (8), and at least one cathode (9); and an injecting device (10) connected to the gas inlet (7) of the cathodic chamber (2) and to the dihydrogen outlet (5) of the anodic chamber (1) or to the dihydrogen inlet (4) of the anodic chamber (1), the injecting device (10) being configured to inject dihydrogen into the cathodic chamber (2) or to block the injection of dihydrogen; and activating the injecting device (10) so as to inject dihydrogen into the cathodic chamber (2) in order to regenerate the cathode (9) during the operation of the fuel cell.

An information processing system comprises a requirement specification acquisition unit for acquiring requirement specification information indicative of a content of a requirement specification relating to a fuel cell; and a fee plan determination unit for determining a fee plan for determining a usage fee of the fuel cell, based on the requirement specification indicated by the requirement specification information. The fee plan may include information indicative of a correspondence between a degree of operation of the fuel cell and the usage fee of the fuel cell.

The invention relates to a method for determining critical operating states in a fuel cell stack, consisting of single cells connected in series, wherein a low-frequency current or voltage signal is applied to the fuel cell stack, the resulting voltage or current signal is measured and the distortion factor thd is determined. According to the invention, the weighted sum of a term dependent on the membrane resistance Rm and a term dependent on the distortion factor thd is used to determine an indicator THDA.sub.dryout correlating with the drying out of the fuel cell membranes of the fuel cell stack, the membrane resistance Rm being detected by impedance measurement.

An electrochemical cell system and a method for operating an electrochemical cell is provided. The method including determining one of a power level, current level or a voltage level of the electrochemical cell, the electrochemical cell including at least one cell having an anode side and a cathode side, the electrochemical cell further having a water transport plate operably coupled to the cathode side. An oxidant pressure level is determined in the cathode side. A water pressure level is determined in the water transport plate. The active area of the at least one cell is changed by adjusting at least one of the oxidant pressure level or the water pressure level based at least in part on the determined power level, current level or voltage level.

An electrochemical cell system and a method for operating an electrochemical cell is provided. The method including determining one of a power level, current level or a voltage level of the electrochemical cell, the electrochemical cell including at least one cell having an anode side and a cathode side, the electrochemical cell further having a water transport plate operably coupled to the cathode side. An oxidant pressure level is determined in the cathode side. A water pressure level is determined in the water transport plate. The active area of the at least one cell is changed by adjusting at least one of the oxidant pressure level or the water pressure level based at least in part on the determined power level, current level or voltage level.

The invention relates to a method for controlling the functioning of a fuel cell comprising at least one membrane, comprising the following steps: putting at least two conductive means in contact with two different surface elements of the same first conductive plate, said plate being able to be a distribution plate belonging to a first cell, measurement of one or more electrical voltages between said conductive means electrically connected to an electrical-voltage measurement device.