Fuel cell system and method thereof

A fuel cell system having a fuel cell supplied with an anode gas and a cathode gas to generate electricity from the fuel cell depending on a load, comprising:

• a supply valve for supplying the anode gas into an anode system of the fuel cell system;
• a purge valve for discharging an off-gas from the anode system;
• a pressure detecting portion that estimates or measures a pressure inside the anode system;
• and
• a hydrogen concentration estimating portion that,
• estimates the hydrogen concentration inside the anode system based on a pressure decrease during the purge valve open duration when a predetermined time elapses after the purge valve is opened in the supply valve close state.

A fuel cell system having a fuel cell supplied with an anode gas and a cathode gas to generate electricity from the fuel cell depending on a load, comprising:

• a supply valve for supplying the anode gas into an anode system of the fuel cell system;
• a purge valve for discharging an off-gas from the anode system;
• a pressure detecting portion that estimates or measures a pressure inside the anode system;
• and
• a hydrogen concentration estimating portion that,
• estimates the hydrogen concentration inside the anode system based on each of a pressure decreases during the purge valve open duration and a pressure decrease during the purge valve close duration in the supply valve close state.

A method of fuel cell system, the fuel cell system comprising:

• a fuel cell supplied with an anode gas and a cathode gas to generate electricity from the fuel cell depending on a load;
• a supply valve for supplying the anode gas into an anode system of the fuel cell system;
• and
• a purge valve for discharging an off-gas from the anode system;
• a pressure detecting portion that estimates or measures a pressure inside the anode system,
• the method comprising estimating a hydrogen concentration inside the anode system based on a pressure decrease during the purge valve open duration when a predetermined time elapses after the purge valve is opened in the supply valve close state.