Method for controlling a fuel cell

A method for controlling a fuel cell having a fuel cell stack comprised of a plurality of unit cells to which a reformed fuel and an oxidizing agent are supplied, said method comprising the steps of:

• using at least one of said plurality of unit cells constituting said fuel cell stack as a monitoring cell, said monitoring cell, for a given output current Is through said stack, having a voltage thereacross which is less than the voltage across said remaining unit calls for said given output current;
• generating electric power while keeping said monitoring cell at a voltage having a constant value;
• detecting said output current from said fuel cell stack, said output current being proportional to consumed amounts of said reformed fuel and said oxidizing agent;
• calculating the difference between the value of said output current I.sub.s and a predetermined current value I.sub.o ;
• and
• varying the amount of said fuel and/or oxidizing agent to be supplied in accordance with said difference so as to minimize said difference by reducing the amount supplied when I.sub.s >I.sub.o and increasing the amount supplied when I.sub.s <I.sub.o, whereby electric power is generated in a stable manner.