A fuel cell system includes a fuel cell generating electric power by a reaction between a fuel gas and an oxidant gas, an injector supplying the fuel gas to the fuel cell, a discharge line in which an off-gas discharged from the fuel cell flows, an ejector recirculating the off-gas flowing in the discharge line to the fuel cell using a flow of the fuel gas from the injector, a discharge valve discharging the off-gas flowing in the discharge line to the outside, and a control device controlling supply of the fuel gas by the injector and opening and closing of the discharge valve. When supply of the fuel gas by the injector is stopped, the control device opens the discharge valve while the off-gas is recirculated to the fuel cell and closes the discharge valve before supply of the fuel gas by the injector is restarted.

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.

To provide a fuel cell system including: a fuel cell group including a plurality of fuel cells; a refrigerant distribution passage through which a refrigerant is individually distributed to the fuel cells composing the fuel cell group; a pre-distribution refrigerant flow rate acquiring unit configured to acquire a first outlet temperature flow rate that is a flow rate of the refrigerant before distribution; a first outlet temperature detecting unit that is provided at a refrigerant outlet of at least one first fuel cell in the fuel cell group in the refrigerant distribution passage, and is configured to detect a first outlet temperature that is a refrigerant outlet temperature of the first fuel cell; a voltage acquiring unit configured to acquire at least a first voltage that is a voltage of the first fuel cell; a current acquiring unit configured to acquire at least a first current that is a current of the first fuel cell; and a controller that calculates a first individual supply flow rate of the first fuel cell on the basis of the first voltage, the first current, and the first outlet temperature, and calculates a second individual supply flow rate of at least one second fuel cell other than the first fuel cell on the basis of the first individual supply flow rate and the pre-distribution refrigerant flow rate.

The present disclosure is directed to a method for tuning the performance of at least one electrochemical cell of an electrochemical cell stack. The method includes supplying power to an electrochemical cell stack. The electrochemical cell stack includes a plurality of electrochemical cells. The method further includes monitoring a parameter of at least one electrochemical cell and determining if an electrochemical cell becomes impaired. The method also includes diverting a fraction of the current flow from the impaired electrochemical cell during operation of the electrochemical cell stack.

A fuel cell vehicle according to the present disclosure includes: a fuel cell; a multiphase converter configured to control an output current of the fuel cell; a current sensor provided in each phase of the multiphase converter; an electric load configured to receive power supplied from the fuel cell; and a control unit. The control unit performs, when it detects an excess or a deficiency of electric energy of the electric load, replacement of phases driven by the multiphase converter while the output current of the fuel cell is kept constant, and determines, when the excess or the deficiency of the electric energy of the electric load is eliminated after the replacement of the phases, that an offset failure has occurred in the current sensor provided in the phase that has been driven before the replacement.

A fuel cell system includes: a fuel cell; a supply device; and a control unit configured to lower output voltage of the fuel cell to a target value so as to execute recovery processing to recover power generation performance of the fuel cell. In a case of having an execution request of the recovery processing, the control unit restarts power generation of the fuel cell when open circuit voltage of the fuel cell is lowered to or smaller than a threshold value higher than the target value by controlling a flow rate of a cathode gas while the power generation of the fuel cell is paused, and the control unit executes the recovery processing while controlling an output current value of the fuel cell to be smaller than an idle current value that is an output current value of the fuel cell in an idle operation state.

A fuel cell system includes a fuel cell that generates electric power using fuel gas and oxidant gas, a fuel gas supply path through which the fuel gas is supplied to an anode inlet of the fuel cell, a recycle gas path through which anode off-gas discharged from an anode outlet of the fuel cell returns to the fuel gas supply path, and a pressure booster arranged in the recycle gas path, and the pressure booster is arranged above a confluence portion where the fuel gas supply path and the recycle gas path meet each other when gravity acts downward from above.

Systems and methods are provided for operating molten carbonate fuel cells to allow for periodic regeneration of the fuel cells while performing elevated CO.sub.2 capture. In some aspects, periodic regeneration can be achieved by shifting the location within the fuel cells where the highest density of alternative ion transport is occurring. Such a shift can result in a new location having a highest density of alternative ion transport, while the previous location can primarily transport carbonate ions. Additionally or alternately, periodic regeneration can be performed by modifying the input flows to the fuel cell and/or relaxing the operating conditions of the fuel cell to reduce or minimize the amount of alternative ion transport.

The present disclosure generally relates to systems and methods for using an energy storage device to assist a venturi or an ejector in a fuel cell or fuel stack system.

A hydrogen supply control system for a fuel cell is provided. The system includes a fuel cell stack that generates electricity using supplied hydrogen and air and a recirculation line that supplies hydrogen discharged from an outlet of the fuel cell stack back to an inlet of the fuel cell stack. A purge valve is disposed at an outlet side of the fuel cell stack of the recirculation line and discharges hydrogen in the recirculation line to the outside as the outlet is opened. A recirculation determining processor determines a recirculation state of the recirculation line and a concentration estimator estimates a purge amount for each gas, which is purged by the purge valve, based on the determined recirculation state and estimates a concentration of hydrogen in the recirculation line based on the estimated purge amount for each gas.