A fuel cell system includes a fuel cell that generates power through electrochemical reaction between fuel gas and oxidant gas, a fuel gas supply path for supplying the fuel gas to an anode of the fuel cell, an offgas discharge path for discharging offgas from the anode of the fuel cell, a recycle gas path bifurcated from the offgas discharge path at a bifurcation and then joining the fuel gas supply path, a flow rate adjuster that is provided on the recycle gas path and adjusts a flow rate of gas flowing through the recycle gas path, a purge valve provided on the offgas discharge path downstream of the bifurcation, and a controller that controls the flow rate adjuster so that an internal pressure of the offgas discharge path upstream of the purge valve is positive.

The fuel cell system includes: a fuel cell 40 that receives supply of reactant gas to generate power; output characteristic updating means for updating an output characteristic of the fuel cell 40 based on output current and output voltage measured by a current sensor 140 and a voltage sensor 150; maximum power calculation means for calculating, using the output characteristic, the maximum power available at the fuel cell 40; and determination means for determining whether a value of the output characteristic is in an assumed situation where the output characteristic value is assumed to be temporarily lowered, wherein while the output characteristic value is determined by the determination means to be in the assumed situation, the maximum power calculation means calculates the maximum power using the output characteristic updated by the output characteristic updating means just before transition to the assumed situation.

A fuel cell system includes: a fuel cell that generates electricity by an electrochemical reaction of a fuel gas with an oxidant gas; a supply channel that supplies the fuel gas to an anode; a recycle channel that supplies an anode off-gas discharged from the anode, as the fuel gas, to the supply channel; a discharge channel that is connected to the recycle channel between the anode and the circulation pump, that is arranged in the recycle channel, and that discharges the anode off-gas to outside; a controller that brings a purge valve, that is provided on the discharge channel, into an open state and determines whether a purge operation to discharge the anode off-gas to the outside is abnormal, and performs an operation to decrease a flow rate of the fuel gas supplied to the anode when determining that the purge operation is abnormal.

The object of the present invention is to balance: the suppression of deterioration of a fuel cell and degradation of its durability and the optimization of the output control of the fuel cell. The present invention provides an output control apparatus for a fuel cell, being capable of switching a control mode between a power control mode in which an output power of a fuel cell connected to a load is controlled so as to be at a target power and a voltage control mode in which an output voltage of the fuel cell is controlled so as to be at a target voltage, wherein a control in the voltage control mode is performed when the output voltage of the fuel cell decreases below a predetermined low voltage threshold value.

Systems and methods for providing power to one or more loads on an aircraft are provided. A power system for an aircraft can include a first fuel cell configured to provide base power to one or more loads on the aircraft. The power system can further include a second fuel cell configured to provide peak power to the one or more loads on the aircraft. The peak power can be a power exceeding the base power. The power system can further include an energy storage device configured to provide transient power to the one or more loads on the aircraft. The transient power can be a power exceeding the peak power. The power system can further include a controller configured to control delivery of power from the first fuel cell, the second fuel cell, and the energy storage device to the one or more loads on the aircraft.

A fuel cell system according to one embodiment performs refresh control of an electrode catalyst of a fuel cell, by reducing a stack voltage as a voltage of the fuel cell to a refresh voltage at which the electrode catalyst is activated. The system includes the fuel cell that generates electric power by an electrochemical reaction using fuel gas and oxidation gas, a stack voltage sensor that sensors the stack voltage, and a controller that controls power of the fuel cell. When a high load demand that makes the stack voltage lower than a given voltage is made on the fuel cell, the controller causes the fuel cell to deliver power commensurate with the high load demand, and performs refresh control when the stack voltage becomes lower than the given voltage through the above control.

The present invention provides a thermoelectric cooperative control method for the SOFC system based on fractional order sliding mode variable structure, comprising the following steps: S1, collecting parameters of system states and output under combinations of different input parameters of the SOFC system, acquiring an influence function of steady-state power, temperature, efficiency response characteristics and bypass valve opening BP within a full load interval on efficiency optimization, as well as an efficiency optimization function within a specified load switching interval and under a time-delay condition; S2, acquiring a local optimal steady-state operation function, a global optimal function under the steady state developed and formed, and a power tracking function with different switching intervals and different time-delay conditions; S3, calculating a sliding mode interval; S4, calculating a series reaching law function according to optimization functions; S5, eliminating chattering of the series reaching law function through a fractional order optimization method, and solving the reaching law by calculation. The present method can provide precise, flexible and stable control, greatly speed up the switch process, overcome time-delay feature of the great inertia of the SOFC system, and realize fast load switching.

A technique of diagnosing a fuel cell stack is provided. In particular, current and voltage of a fuel cell stack are measured during driving of a fuel cell vehicle and the current and voltage are sequentially stored. It is then determined based on the stored current whether the vehicle is being operated at constant current. Different factors are analyzed depending on whether the vehicle is being operated at constant current, and then it is determined whether the fuel cell stack is in a normal state. A moisture supply into the fuel cell stack is calculated if it is determined that the fuel cell stack is not in the normal state. Based on the calculated moisture supply, whether the fuel cell stack is in a dryout state is diagnosed.

A method of cleaning power cells in an array of power cells, comprising coupling at least one first power cell to second power cells in an array of power cells and causing the second power cells to drive the at least one first power cell with a voltage to clean catalyst on the at least one first power cell.

A fuel cell vehicle includes an in-vehicle electric load, a fuel cell stack, which is electrically connected to the in-vehicle electric load, a power storage device, which is electrically connected to the fuel cell stack so as to be electrically connected in parallel to the in-vehicle electric load, a state-of-charge sensor, which is configured to detect a state of charge of the power storage device, and circuitry that is configured to switch, in multiple stages, a power generated by the fuel cell stack based on the state of charge of the power storage device detected by the state-of-charge sensor. The circuitry is configured to set, at least at one of the multiple stages, a power generation command value in accordance with selected one of a plurality of operation modes that have different power generation command values.