A method for controlling a fuel cell system is provided. The method includes upon start of a fuel cell stack, obtaining a flow rate of air supplied into a cathode after an air regulator for regulating the air supplied into the cathode is opened. A sealing state of the fuel cell stack is then determined based on the obtained flow rate of the air.

A method of controlling an air compressor motor for a fuel cell vehicle is provide. The method includes calculating a counter electromotive force constant of the air compressor motor based on a voltage and a current of the air compressor motor for the fuel cell vehicle supplying air to a fuel cell stack and a rotation speed of the air compressor motor. The method additionally includes determining whether a permanent magnet of the air compressor motor is demagnetized based on a result of comparison between the calculated counter electromotive force constant value and a pre-set counter electromotive force constant design value.

Systems and methods for operating an electric energy storage device are described. The systems and methods may generate a state of charge estimate that is based on negative electrode plating. An overall state of charge may be determined from the state of charge estimate that is based on negative electrode plating and a state of charge estimate that is not based on negative electrode plating.

A fuel cell system includes: a fuel cell; a voltage detector; a current detector; an alternating current signal supply unit; a phase difference calculation unit configured to calculate, based on detected alternating voltage and detected alternating current, a phase difference between the detected alternating current and the detected alternating voltage; and an estimation unit configured to estimate, in accordance with the phase difference, an electric power generation distribution feature amount representing an electric power generation distribution in a cell surface of the fuel cell, with use of a predetermined relationship between the electric power generation distribution feature amount and the phase difference. The electric power generation distribution feature amount includes a value indicating a difference between a maximum value and a minimum value of local current density in the cell surface.

A method for evaluating voltage sensor output using a diagnostic system includes: measuring an overall fuel cell stack voltage using a stack voltage sensor; identifying a fuel cell voltage of a first end cell using a first end cell voltage sensor and a second end cell using a second end cell voltage sensor; determining if a maximum value of the overall fuel cell stack voltage, the fuel cell voltage of the first end cell or the second end cell is less than a sensor limit, and if a minimum value of the fuel cell voltages is greater than the sensor limit; performing a test to identify if the maximum value is greater than an average sensor signal value and if the average sensor signal value is greater than the minimum value; and conducting a test to identify if the minimum value is less than a first predetermined threshold.

A controller closes a cutoff valve and a purge valve when a pressure value detected by a pressure sensor is an abnormal value. The controller then judges that an on-off valve has failed when the pressure value detected by the pressure sensor P1 has lowered, whereas the controller judges that the pressure sensor has failed when the pressure value detected by the pressure sensor has not lowered.

A fuel cell device may includes: a housing including a top panel and a plurality of side panels; a fuel cell module disposed in the housing, the fuel cell module housing a cell stack that carries out power generation by utilizing a fuel gas and an oxygen-containing gas; and a plurality of auxiliary machines that assist operation of the fuel cell module. A plurality of panels among the top panel and the plurality of side panels may serve as a maintenance panel that can be detached during maintenance or component replacement, and at least two panels among the top panel and the plurality of side panels do not serve as the maintenance panel.

A fuel cell system includes: a fuel cell unit; first and second supply systems; a switching device; a switching control unit, when required power of the fuel cell unit is equal to or smaller than a threshold; an open circuit voltage obtaining unit; and a supply system control unit.

A fuel cell system including: a fuel cell; a voltage sensor that measures output voltage of the fuel cell; a converter that boosts the output voltage; and a control unit that controls the converter using a duty ratio including a feedforward term and a feedback term, the feedforward term being set to perform feedforward control, the feedback term being set to perform feedback control, wherein when the control unit causes the converter to boost the output voltage, and when the feedforward term calculated by specified Expression I exceeds an upper limit calculated by specified Expression II, the control unit causes the converter to boost the voltage output from the fuel cell with the duty ratio including the upper limit and the feedback term.

A method and apparatus for parallel operation of multiple power sources including one fuel cell power source. The apparatus includes a droop controller master communicatively connected to the multiple power sources and configured to measure a load demand for the multiple power sources, a first droop controller slave communicatively connected to the droop controller master and to a first fuel cell power source, the first droop controller configured to calculate a first droop profile for the first fuel cell power source, a second droop controller slave communicatively connected to the droop controller master and to a second power source, and a first inverter, electrically connected to the first fuel cell power source and communicatively connected to the first droop controller slave, and configured to output power according to a first droop profile.