Fuel cell system and current control method of same

A fuel cell system comprising:

• a fuel cell having a plurality of cells;
• a cell monitor for detecting cell voltage in each of the cells;
• and a control calculation unit for PI-compensating a request current corresponding to a system request electric power requested by the system based on a minimum cell voltage detected by the cell monitor, wherein
• the control calculation unit is provided with:
• a minimum cell voltage deviation calculation device that calculates deviation between a prescribed minimum cell voltage reference value and the minimum cell voltage detected by the cell monitor;
• a PI calculation device that calculates a current limit value based on the deviation between the minimum cell voltage reference value and the detected minimum cell voltage;
• a request current calculation device that calculates a request current based on the system request electrical power;
• a target current value calculation device that calculates a deviation between the request current and the current limit value as a target current value;
• an electric power distribution calculation device that calculates the upper limit and lower limit of an electric power command value for the fuel cell based on the target current value;
• and
• a current/voltage command value calculation device that calculates a current command value and a voltage command value defining an output current and output voltage of the fuel cell based on the upper limit and lower limit of the electric power command value, and wherein
• the control calculation unit changes the proportional gain for the PI compensation of the request current based on a present fuel cell current value in a case where the detected minimum cell voltage is equal to or less than a prescribed threshold value.

A current control method for a fuel cell system provided with a fuel cell having a plurality of cells, the method comprising:

• detecting the cell voltage in each of the cells;
• PI-compensating a request current corresponding to a system request electric power requested by the system based on a minimum cell voltage;
• and
• changing a proportional gain for the PI compensation of the request current based on a present current fuel cell current value.