Introduced is an fuel cell power net including a fuel cell configured to generate power through a reaction between a fuel gas and an oxidizing gas, a power storage device configured to be charged with power generated by the fuel cell or discharged to supply power, a main line configured to electrically connect the fuel cell and the power storage device to each other; a main relay disposed on the main line so as to break or make an electrical connection between the fuel cell and the power storage device, a bypass line which is branched from the main line, bypasses the main relay, and is connected to the power storage device, a bypass relay disposed on the bypass line so as to break or make an electrical connection of the bypass line, and a controller configured to control the main relay or the bypass relay such that the power stored in the storage device is supplied to the fuel cell while the power generation of the fuel cell is stopped.

Disclosed are a control system for a fuel cell including a fuel cell configured to receive a fuel gas and an oxidation gas and generate electric power, a current controller configured to control an output current output from the fuel cell, based on a demanded current of the fuel cell, while maintaining an output voltage output from the fuel cell at a preset voltage or more, and a restriction controller configured to estimate an output current at the preset voltage as a maximum current when the output voltage of the fuel cell drops to become equal to or smaller than the preset voltage, and restrict the output current of the fuel cell to not more than a first restriction current set based on the estimated maximum current, and a control method for a fuel cell.

A method for controlling a fuel cell system having a hydrogen fuel injector/ejector and a control system, includes determining a hydrogen fuel consumption rate associated with a selected power level at steady state, determining a modeled hydrogen fuel flow rate associated with the selected power level and the injector/ejector, determining a modeled effective flow area associated with the injector/ejector, determining a true effective flow area of the injector/ejector, and using the effective flow area to calculate or adjust a command signal, an estimation or an estimation error of at least one of a hydrogen fuel flow rate, an anode leak rate and an anode exhaust valve flow rate.

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.

In a case where each of the temperature, the impedance, and the output current of a fuel cell stack falls within a predetermined range, the output voltage of the fuel cell stack is measured, and the measured output voltage is compared with a reference value to thereby determine the degree of degradation of the fuel cell stack.

Disclosed are an apparatus for measuring an impedance of a fuel cell in a system to which a DC-DC converter is applied and a method thereof. The method includes calculating an impedance of a fuel cell stack based on an impedance of an output terminal of the fuel cell stack measured in a state in which the output of the fuel cell stack is drawn and the impedance of the output terminal of the fuel cell stack measured in a state in which the drawing of the output of the fuel cell stack is stopped.

A method for controlling a fuel cell system having a hydrogen fuel injector/ejector and a control system, includes determining a hydrogen fuel consumption rate associated with a selected power level at steady state, determining a modeled hydrogen fuel flow rate associated with the selected power level and the injector/ejector, determining a modeled effective flow area associated with the injector/ejector, determining a true effective flow area of the injector/ejector, and using the effective flow area to calculate or adjust a command signal, an estimation or an estimation error of at least one of a hydrogen fuel flow rate, an anode leak rate and an anode exhaust valve flow rate.

Disclosed are a device and a method for controlling a fuel cell system, in which during operation of the fuel cell system, the device and method determine a minimum motoring current limit value applied to a motor for driving a fuel cell vehicle by varying an output current limit threshold value of the fuel cell stack by determining an available output current of the stack and by varying an available voltage lower limit threshold value of the stack by determining an available operating voltage of the stack, thereby preventing the fuel cell vehicle from rattling due to excessive limitation of output current of the stack. They also control the pressures of an anode and a cathode of the stack by monitoring whether the performance of the stack is degraded as limitation of output current of the stack is suppressed, thereby suppressing degradation of the performance of the stack.

A method of distributing power in a fuel cell system including a plurality of fuel cell stacks, includes determining, by a controller, a total system power demand, which is a power demand of the fuel cell system, determining an operation order of the fuel cell stacks based on a state of the fuel cell stacks, determining the number of operation fuel cell stacks among the plurality of fuel cell stacks based on the total system power demand and an average available power of the fuel cell stacks, determining operation target fuel cell stacks based on the operation order of the fuel cell stacks and the number of operation fuel cell stacks, and determining a power demand of each of the operation target fuel cell stacks based on the total system power demand and an effective catalyst reaction area ratio of each fuel cell stack included in the operation target fuel cell stacks.

According to the present embodiment, the first fuel cell group is formed of a plurality of fuel cell stacks connected in series. The first power converter is capable of controlling a first power to be generated by the first fuel cell group according to a first output current. The second fuel cell group is formed of a plurality of fuel cell stacks connected in series, the fuel cell stacks corresponding respectively to the fuel cell stacks in the first fuel cell group. The second power converter is capable of controlling a second power to be generated by the second fuel cell group according to a second output current. Oxygen-containing gas is supplied through the first pipe to each of the fuel cell stacks in the first fuel cell group and each of the fuel cell stacks in the second fuel cell group.