Method for controlling fuel cell device

A method of controlling a fuel cell device in which an electrolyte membrane is inserted between a fuel electrode and an oxidant electrode, hydrogen is supplied to a hydrogen supply unit of the fuel electrode, and a gas containing oxygen is supplied to a gas supply unit of the oxidant electrode so that power is generated, the method comprising:

• a step of determining whether impedance between the fuel electrode and the oxidant electrode is greater than a predetermined threshold during a steady operation of the fuel cell device;
• a step of decreasing a flow rate of a gas circulating via a circulation passage connecting a gas introduction passage of the gas supply unit to a gas discharge passage of the gas supply unit when the impedance is greater than the predetermined threshold;
• a step of measuring a voltage between the fuel electrode and the oxidant electrode when the impedance is equal to or less than the predetermined threshold, and determining whether the voltage is equal to or less than a first predetermined threshold;
• and
• a step of increasing the flow rate of the gas circulating via the circulation passage when the voltage is equal to or less than the first predetermined threshold.