A fuel cell system and a control method thereof reduce a hydrogen exhaust amount and perform precise control in a low output section through the control of an air recirculation line and an air recirculation valve that recirculate the air discharged from the cathode of a fuel cell stack to the cathode.

A fuel cell system herein may include a battery configured to supply electric power to a fuel cell auxiliary device used for activating a fuel cell stack. When remaining electric energy in the battery is higher than an electric energy threshold upon activation of the fuel cell stack, a controller of the fuel cell system may start outputting current from the fuel cell stack after a fuel concentration in the fuel cell stack reaches a predetermined fuel concentration threshold, and when the remaining electric energy decreases below the electric energy threshold while the fuel concentration is being increased, the controller may start outputting current from the fuel cell stack regardless of the fuel concentration in the fuel cell stack. The current can be obtained from the fuel cell stack even when the remaining electric energy in the battery is low.

A fuel cell system herein may include a battery configured to supply electric power to a fuel cell auxiliary device used for activating a fuel cell stack. When remaining electric energy in the battery is higher than an electric energy threshold upon activation of the fuel cell stack, a controller of the fuel cell system may start outputting current from the fuel cell stack after a fuel concentration in the fuel cell stack reaches a predetermined fuel concentration threshold, and when the remaining electric energy decreases below the electric energy threshold while the fuel concentration is being increased, the controller may start outputting current from the fuel cell stack regardless of the fuel concentration in the fuel cell stack. The current can be obtained from the fuel cell stack even when the remaining electric energy in the battery is low.

Disclosed herein is a redox flow battery (RFB). The battery generally includes: a positive electrolyte that is a first metal ion, a negative electrolyte that is a second metal ion, an ion exchange membrane positioned between the positive electrolyte and the negative electrolyte. The membrane is configured to restrict and/or prevent the passage of the first metal ion and/or the second metal ion therethrough, and is configured to maintain ionic conductivity between the positive electrolyte and the negative electrolyte.

A fuel cell system for air vehicles, wherein the fuel cell system comprises: a fuel cell, a fuel gas system for supplying fuel gas to the fuel cell, a potential sensor, and a controller; wherein the fuel gas system comprises a fuel gas supplier; wherein the controller determines whether or not a potential of the fuel cell measured by the potential sensor, is a reversal potential; and wherein, when the controller determines that the potential of the fuel cell is a reversal potential, the controller increases a fuel gas supply from the fuel gas supplier to the fuel cell.

A system for estimating the amount of purge of a fuel cell is provided. The system includes a fuel cell that generates power by receiving hydrogen at an anode side and receives oxygen at a cathode side. A recirculation line is connected with the anode side of the fuel cell, and the gas included hydrogen therein is circulated in the recirculation line. A flow amount estimator estimates the flow amount of gas inside the recirculation line. A purge valve is positioned in the recirculation line and discharges the gas in the recirculation line to the outside when opened. A purge amount estimator estimates the amount of purge for each gas discharged through the purge valve by reflecting the flow amount of the gas estimated by the flow amount estimator.

A control unit estimates a discharged fuel gas amount, i.e., an amount of fuel gas discharged from the outlet of a cathode flow field, of a fuel exhaust gas introduced from a communication flow path to the inlet of the cathode flow field and then flowing through a cathode. The control unit calculates an oxygen-containing gas amount necessary for dilution at the time of discharge into the atmosphere, from the estimated discharged fuel gas amount, and sets a discharge amount of the air pump, based on the calculated oxygen-containing gas amount.

A fuel cell system (200) for providing electrical energy. The system (200) comprises a fuel cell stack (201), an anode subsystem (203) with a proportional valve (205) for dosing a volume of gas to be fed to the fuel cell stack (201), a purge valve (207) for discharging gas from the anode subsystem (203) into an exhaust-gas path (209) of the fuel cell system (200), and a control unit (211) for controlling the proportional valve (205) and the purge valve (207). The control unit (211) is configured to use an electrical control current that is fed to the proportional valve (205) to readjust for a purging operation to draw conclusions regarding a hydrogen concentration in a gas that is fed to the purge valve (207), wherein the control unit (211) is furthermore configured to adjust the fuel cell system (200) in a manner dependent on the determined hydrogen concentration.

To provide a fuel cell system configured to suppress irreversible performance degradation of a fuel cell. A fuel cell system wherein the controller preliminarily stores a data group indicating a relationship between, when a predetermined amount of hydrogen gas is supplied from the fuel gas supplier, an amount of the supplied hydrogen gas and a hydrogen pressure increase rate; wherein the controller calculates a fuel gas pressure increase rate from a pressure change detected by the pressure sensor when the fuel gas is supplied to the fuel cell; wherein the controller determines whether or not the fuel gas pressure increase rate is smaller than the hydrogen pressure increase rate; and wherein, when the controller determines that the fuel gas pressure increase rate is smaller than the hydrogen pressure increase rate, the controller prohibits power generation of the fuel cell.

An illustrative example system for managing hydrogen utilization in a fuel cell power plant includes a first hydrogen concentration sensor that provides an indication of a first concentration of hydrogen in a fluid flowing into an anode inlet of the power plant. A second hydrogen concentration sensor provides an indication of a second concentration of hydrogen in a fluid flowing out of an anode exit of the power plant. A processor determines a utilization of hydrogen by the power plant based on the first and second concentrations.