A fuel cell system wherein the fuel cell comprises an electrolyte membrane; wherein the electrolyte membrane is a perfluorosulfonic acid (PFSA) membrane; wherein the controller has a data group showing a correlation between the current of the fuel cell and the temperature of the fuel cell which is necessary to keep a moisture content of the electrolyte membrane at a predetermined moisture content threshold or more; and wherein, when the temperature and voltage of the fuel cell become a predetermined first temperature threshold or more and a predetermined voltage threshold or more, respectively, the controller conducts a temperature dropping time power generation mode in which power generation is conducted while controlling the current of the fuel cell with reference to the data group, until the temperature of the fuel cell becomes a predetermined second temperature threshold which is lower than the first temperature threshold.

A method for operating a fuel cell device comprising a fuel cell stack having at least one fuel cell, involving the steps; a) drying of the fuel cell stack upon switching off the fuel cell device; b) determining the membrane residual water and the cathode residual water by means of electrochemical impedance spectroscopy when restarting the fuel cell device; c) using a cell voltage monitoring unit to identify the wettest cathode in one of the fuel cells; d) model-based determination of the water transport from the wettest cathode to the anode and thus the anode moisture in the fuel cell device; and; e) adjusting the electric current and the fuel volume flow in dependence on the anode moisture. A fuel cell device and a motor vehicle having a fuel cell device is also provided.

A control device switches between a first injection control of injecting the fuel gas by sequentially providing periods during which at least one of the plurality of injectors injects the fuel gas if it is determined that the power generation state of the fuel cell stack is stable based on a detected power generation state, and a second injection control of injecting the fuel gas by intermittently providing periods during which the plurality of injectors simultaneously inject the fuel gas if it is determined that the power generation state of the fuel cell stack is not stable based on the detected power generation state.

A fuel cell system includes a solid oxide fuel cell capable of generating power by receiving a supply of a reformed gas and an oxidant gas; an oxidant gas supply device that supplies the oxidant gas to the fuel cell; a reforming unit that supplies the reformed gas to the fuel cell; a fuel supply device that supplies a fuel which is a raw material for the reformed gas to the reforming unit; a combustion unit that combusts discharged gases of the fuel cell, wherein the reforming unit can reform the fuel into the reformed gas by exchanging heat with a combustion gas produced by the combustion unit; and a first control unit controls the fuel supply device to additionally supply the fuel to the fuel cell through the reforming unit in order to prevent the oxidant gas from flowing in from downstream of a fuel electrode of the fuel cell at the time of stopping the system. The fuel cell system further includes a second control unit that controls to supply the fuel to the reforming unit before the additional supply so that the temperature of the reformed gas flowing into the fuel cell does not exceed a predetermined temperature at the time of stopping the system.

Methods and systems are provided for iron preformation in a redox flow battery. In one example, a method may include, in a first condition, discharging and then charging the redox flow battery, and in a second condition, charging the redox flow battery including preforming iron metal at a negative electrode of the redox flow battery, and thereafter entering an idle mode of the redox flow battery including adjusting one or more electrolyte conditions. In some examples, each of preforming the iron metal and adjusting the one or more electrolyte conditions may increase a battery charge capacity to greater than a threshold battery charge capacity.

Disclosed are a fuel cell power net system and a method for controlling the same. The fuel cell power net system includes: a fuel cell controller configured to control current output from a fuel cell unit; at least one DC/DC converter configured to boost DC voltage and to output the boosted DC voltage; a battery connected to the fuel cell unit in parallel so as to supply DC power to the fuel cell unit; a load controller configured to provide demand output information; and a fuel cell power controller configured to receive the demand output information, to calculate output levels required by the fuel cell unit and the battery, to compare a current output level of the fuel cell unit with the output level required by the fuel cell unit, and to provide a control value to the fuel cell controller depending on a result of the comparison.

A system includes a fuel cell stack and a controller. The controller is configured to determine a current density of the fuel cell stack, determine a threshold voltage value, and compare a measured average fuel cell voltage value and the threshold voltage value. The controller is configured to set an allowed current and power draw of the fuel cell stack.

A device for controlling a line connection type fuel cell system and a method for the same are provided. The device for controlling a line connection type fuel cell system includes a plurality of fuel cell modules, an Alternating Current (AC) voltage generator, and a controller to activate the AC voltage generator to generate an AC voltage corresponding to power supplied from a system, and to control the plurality of fuel cell modules to generate a current in synchronization with the AC voltage.

Disclosed is a fuel cell system and a method for controlling the same which in a constant current operation mode in which an output current of a fuel cell stack is constant, controls a hydrogen supply unit, an air supply unit, or a hydrogen recirculation unit differently depending on the size of a target output current to prevent the local flooding of the fuel cell stack in the constant current operation mode.

Methods and systems are provided for iron preformation in a redox flow battery. In one example, a method may include, in a first condition, discharging and then charging the redox flow battery, and in a second condition, charging the redox flow battery including preforming iron metal at a negative electrode of the redox flow battery, and thereafter entering an idle mode of the redox flow battery including adjusting one or more electrolyte conditions. In some examples, each of preforming the iron metal and adjusting the one or more electrolyte conditions may increase a battery charge capacity to greater than a threshold battery charge capacity.