A fuel cell system that includes a first fuel cell that generates electric power using a hydrogen-containing fuel gas; a second fuel cell that generates electric power using off-gas exhausted from the first fuel cell and containing hydrogen that has not reacted in the first fuel cell; a first control device that controls the electric power output from the first fuel cell by adjusting a current or a voltage being output from the first fuel cell; a second control device that controls the electric power output from the second fuel cell by adjusting a current or a voltage being output from the second fuel cell; and an output control device that controls at least one of the first control device or the second control device such that a total electric power being generated by the first fuel cell and the second fuel cell approaches an electric power demand.

An industrial vehicle having a fuel cell system includes a vehicle key switch which has at least an ON position and an OFF position and is switchable between the ON position and the OFF position and a controller configured to control the fuel cell system in conjunction with manipulation of the key switch. When the controller detects that the key switch is turned from the OFF position to the ON position, the controller causes the fuel cell system to start electric power generation. When the controller detects that the key switch is turned from the ON position to the OFF position, the controller causes the fuel cell system to start a voltage maintenance control. When the controller detects that the key switch at the ON position is manipulated in a specified manner, the controller causes the fuel cell system to stop the electric power generation.

An electric power adjustment system includes a fuel cell connected to a load, and a multi-phase converter connected between the fuel cell and the load. The multi-phase converter is constituted of a plurality of phases and converts an output voltage from the fuel cell by a predetermined required voltage ratio. The electric power adjustment system includes a ripple current characteristic switching unit configured to switch a ripple current characteristic with respect to an input current to the multi-phase converter by changing at least one of a drive phase number and the voltage ratio of the multi-phase converter according to an operation state of the fuel cell and a required electric power of the load.

Systems and methods are provided for managing health of electrolytes of redox flow battery system. Components of the system may include a redox rebalancing cells and a gas storage system. The redox rebalancing cell may be operated by plating iron on a plating electrode, treating a negative electrolyte of the redox flow battery system with the plated iron and returning the negative electrolyte to an electrolyte tank. The gas storage system may include a set of expandable gas storage tanks coupled to at least one electrolyte storage tank and an electrolyte rebalancing system of the redox flow battery system.

Systems and methods are provided for managing health of electrolytes of redox flow battery system. Components of the system may include a redox rebalancing cells and a gas storage system. The redox rebalancing cell may be operated by plating iron on a plating electrode, treating a negative electrolyte of the redox flow battery system with the plated iron and returning the negative electrolyte to an electrolyte tank. The gas storage system may include a set of expandable gas storage tanks coupled to at least one electrolyte storage tank and an electrolyte rebalancing system of the redox flow battery system.

A vehicle power system including a fuel cell auxiliary power unit for providing clean, efficient power to a vehicle. The system generally includes a fuel cell with a first DC output and a heat output, a pressure vessel adapted to contain and provide pressurized hydrogen to the fuel cell, an electrical storage unit with a DC input coupled to the first DC output of the fuel cell. The electrical storage unit also has a second DC output. An inverter is coupled to the second DC output of the electrical storage unit to receive power, the inverter having a first AC output. The system can provide heat, AC power, and DC power to the vehicle.

An onboard electrochemical system of an electrochemical cell including a cathode and an anode separated by an electrolyte separator is selectively operated in either of two modes. In a first mode of operation, water or air is directed to the anode, electric power is provided to the anode and cathode to provide a voltage difference between the anode and the cathode, and nitrogen-enriched air is directed from the cathode to an aircraft fuel tank or aircraft fire suppression system. In a second mode of operation, fuel is directed to the anode, electric power is directed from the anode and cathode to one or more aircraft electric power-consuming systems or components, and nitrogen-enriched air is directed from the cathode to a fuel tank or fire suppression system.

A fuel cell system includes: a fuel cell including a fuel gas passage through which a fuel gas flows and an oxidant gas passage through which an oxidant gas flows, an inlet of the fuel gas passage being located closer to an outlet of the oxidant gas passage than to an inlet of the oxidant gas passage, an outlet of the fuel gas passage being located closer to the inlet of the oxidant gas passage than to the outlet of the oxidant gas passage; an oxidant gas supply unit supplying the oxidant gas to the fuel cell; and a supply amount controller configured to control the oxidant gas supply unit, the supply amount controller is configured to control the oxidant gas supply unit so that a stoichiometric ratio of the oxidant gas in a high-temperature high output power state is greater than that in a high-temperature low output power state.

A method for observing a state of an electrochemical system including a fuel cell including the following steps: measuring parameters that are representative of the fuel cell in operation; forming a control vector; forming a measurement vector; calculating a temporal variation, referred to as a non-corrected temporal variation; calculating a corrective term in sliding mode; calculating an estimate of the state of the electrochemical system; reiterating above steps while incrementing the measurement time.

A fuel cell system includes: a fuel cell; a voltage regulator that regulates an output voltage of the fuel cell; and a controller configured to perform a refresh process of decreasing the output voltage of the fuel cell to a reduction voltage at which an oxide film formed on the cathode is reduced, by controlling the voltage regulator. The controller, before the refresh process, calculates a first amount, the first amount being an amount by which the oxide film is to be removed from the cathode. The controller determines, as the output voltage of the fuel cell, a refresh voltage that enables the first amount of the oxide film to be removed within a preset reference time. The controller operates the voltage regulator so as to cause the output voltage of the fuel cell to become the refresh voltage when the refresh process is performed.