A method of controlling a fuel cell device includes: a step of supplying hydrogen to a hydrogen supply unit; a step of measuring a voltage between a fuel electrode and an oxidant electrode and determining whether the voltage is equal to or greater than a reference voltage; and a step of discharging a gas containing oxygen from the gas supply unit to the outside while supplying the gas to the gas supply unit when the voltage is equal to or greater than the reference voltage.

A dual-battery fuel cell system is provided, including two supplemental batteries, each battery supporting/supplementing operation of a fuel cell stack in the system. Driving conditions associated with a fuel cell vehicle can be obtained. Based on the driving conditions, power sources of the fuel cell vehicle to provide power to fuel cell vehicle system can be determined, the power sources comprising the fuel cell stack and the two supplemental batteries. Operating conditions of each of the power sources can be assessed, and one or more of the power sources can be controlled to deliver power to the fuel cell vehicle system based on the operating conditions of each of the power sources.

A braking control unit of a fuel cell vehicle is configured to, in a period during which the fuel cell vehicle is being braked in response to a braking request, (i) when an estimated amount of stagnant water is less than a predetermined second water amount less than a first water amount, limit an upper limit electric power of a regenerated electric power resulting from regenerative operation to a predetermined first value or below, and (ii) when the estimated amount of stagnant water is greater than or equal to the second water amount, execute an upper limit changing process of setting an upper limit electric power to a second value lower by a predetermined value than the first value.

A system and method for controlling a discharge of residual water remaining in a fuel cell stack after an operation of a fuel cell is ended is provided. The method includes determining whether a preset temperature condition is satisfied, determining whether a preset time condition is satisfied when the temperature condition is satisfied, and discharging residual water in a fuel cell stack while a vehicle travels when the temperature condition and the time condition are satisfied.

A system and method for controlling a discharge of residual water remaining in a fuel cell stack after an operation of a fuel cell is ended is provided. The method includes determining whether a preset temperature condition is satisfied, determining whether a preset time condition is satisfied when the temperature condition is satisfied, and discharging residual water in a fuel cell stack while a vehicle travels when the temperature condition and the time condition are satisfied.

An apparatus for estimating an amount of condensed water in an anode of a fuel cell system includes: an initial anode water vapor amount calculation unit to calculate an initial amount of water vapor in the anode of a fuel cell upon startup, an anode diffusion amount calculation unit to calculate an amount of H.sub.2O diffused from a cathode to the anode, a purge amount calculation unit to calculate an amount of water vapor discharged upon gas purging in the anode, a recirculation amount calculation unit to calculate the amount of water vapor recirculated to the anode, and a condensed water amount determination and water level estimation unit to calculate the actual amount of water vapor in the anode based on values calculated using these units and to calculate the amount of condensed water in a water trap.

An apparatus for estimating an amount of condensed water in an anode of a fuel cell system includes: an initial anode water vapor amount calculation unit to calculate an initial amount of water vapor in the anode of a fuel cell upon startup, an anode diffusion amount calculation unit to calculate an amount of H.sub.2O diffused from a cathode to the anode, a purge amount calculation unit to calculate an amount of water vapor discharged upon gas purging in the anode, a recirculation amount calculation unit to calculate the amount of water vapor recirculated to the anode, and a condensed water amount determination and water level estimation unit to calculate the actual amount of water vapor in the anode based on values calculated using these units and to calculate the amount of condensed water in a water trap.

The invention relates to a media management plate (1) for a fuel cell assembly (5), a fuel cell system (10) comprising the media management plate and a fuel cell assembly, and a method of operating a fuel cell system (10) comprising a fuel cell assembly (5) and the media management plate (1). All lines for supplying and discharging the fuel cell media and all devices necessary for treating the fuel cell media are integrated in the media management plate (1). The media management plate (1) can be heated by means of coolant and is functional both when oriented vertically and horizontally.

The invention relates to a media management plate (1) for a fuel cell assembly (5), a fuel cell system (10) comprising the media management plate and a fuel cell assembly, and a method of operating a fuel cell system (10) comprising a fuel cell assembly (5) and the media management plate (1). All lines for supplying and discharging the fuel cell media and all devices necessary for treating the fuel cell media are integrated in the media management plate (1). The media management plate (1) can be heated by means of coolant and is functional both when oriented vertically and horizontally.

A stack case of a fuel cell system includes a case body, a first end cover, and a second end cover. A recess is formed in an upper surface of the case body. An interruption control unit as an electrical equipment unit is placed in the recess. A plurality of first screw holes are formed in one end surface of the case body, and a plurality of second screw holes are formed in the other end surface of the case body. A first screw hole aligned with a recess in a direction in which a plurality of power generation cells are stacked together penetrates through the case body from one end surface of the case body to a side surface of the recess.