A voltage synchronization method and system are provided. The system includes a main controller that is configured to determine whether voltage synchronization is possible. When the voltage synchronization is determined to be possible, the main controller is configured to transmit a voltage synchronization command to a plurality of auxiliary controllers. The plurality of auxiliary controllers are configured to adjust sensed voltages based on an output voltage of a fuel cell stack when the transmitted voltage synchronization command is received.

A method of operating a fuel cell assembly comprising a plurality of fuel cells connected together for collectively providing power to a load, each fuel cell including an anode and a cathode, the method comprising selectively providing an electrical connection between the anode and the cathode of at least one of the fuel cells of the assembly for lowering the voltage across the fuel cell independent of the load.

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.

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 power converter for a fuel cell is provided. The power converter includes a boost converter connected to the fuel cell and configured to control a load voltage at a predetermined magnitude in a normal operation mode and to induce an output response by applying a predetermined perturbation current to the fuel cell in a diagnosis mode, and a digital signal processor configured to extract an impedance parameter by detecting the output response of the fuel cell in the diagnosis mode, and predict a lifespan of the fuel cell according to the impedance parameter. The normal operation mode is configured to supply a voltage in response to a change of a load and the diagnosis mode is configured to predict the lifespan of the fuel cell.

A fuel battery system includes a fuel battery, an electric storage, a voltage adjuster, a pump, an abnormity detector, and circuitry. The fuel battery generates electricity using fuel gas and oxidant gas. The voltage adjuster is connected to at least one of the fuel battery and the electric storage. The voltage adjuster is configured to adjust voltage output from the fuel battery or the electric storage to output the adjusted voltage to a load. The pump supplies the oxidant gas to the fuel battery using electric power output from at least one of the fuel battery and the electric storage. The voltage adjuster is connected between the fuel battery and the pump. The abnormity detector detects abnormity in the voltage adjuster. The circuitry is configured to restrict the electric power supplied to the pump in a case where the abnormity detector detects the abnormity in the voltage adjuster.

A fuel cell system according to the present invention comprises a control apparatus which performs performance restoration processing for a catalyst layer by decreasing the output voltage of a fuel cell to a predetermined voltage. When an oxide film formed on the catalyst layer during power generation of the fuel cell contains, in addition to a first oxide film that can be removed by decreasing the output voltage of the fuel cell to a first oxide film removal voltage, a second oxide film that can be removed by decreasing the output voltage of the fuel cell to a second oxide film removal voltage which is lower than the first oxide film removal voltage, the control apparatus estimates the amount of the second oxide film and performs performance restoration processing with a set voltage being equal to or lower than the second oxide film removal voltage only when it determines that the estimated amount exceeds a predetermined amount A.

A method of improving the electrical performance of an operating fuel cell catalyst-containing cathode in a fuel cell connected to an electrical load by: reducing the flow of air to the cathode; disconnecting the load from the fuel cell; connecting a potentiostat to the fuel cell; cycling an applied voltage, current, or power to the fuel cell one or more times; disconnecting the potentiostat from the fuel cell; reconnecting the load to the fuel cell; and resuming the flow of air to the cathode.

A control unit of an aging apparatus performs a first pattern of supplying a humidified H.sub.2 gas to an anode and supplying a humidified N.sub.2 gas to a cathode, to thereby move protons from the anode to the cathode through an electrolyte membrane. Further, the control unit performs a second pattern of supplying the humidified N.sub.2 gas to the anode and supplying the humidified H.sub.2 gas to the cathode, to thereby move protons from the cathode to the anode through the electrolyte membrane.

A fuel cell system that can improve an operating efficiency while minimizing an increase in cost for a configuration is provided. A fuel cell system (10) includes a fuel cell stack (11), an air pump (13), and an electric power control unit (15). The air pump (13) is connected to an output terminal of the fuel cell stack (11). The air pump (13) is configured to supply air as an oxidizing agent gas to the fuel cell stack (11). The electric power control unit (15) includes a first circuit unit (31) and a second circuit unit (32). The first circuit unit (31) is connected to the output terminal of the fuel cell stack (11) and is configured to perform step-up electric power conversion on an input from the fuel cell stack (11). The second circuit unit (32) is configured to perform bidirectional electric power conversion for stepping-up an input from the fuel cell stack (11) and for stepping-down an output to the air pump (13).