Fuel cell system and method of controlling fuel cell system

A fuel cell system comprising:

• a fuel cell configured to generate power through a reaction of air supplied to a cathode electrode and hydrogen gas supplied to an anode electrode;
• a compressor configured to supply air to the cathode electrode of the fuel cell;
• an outlet valve connected to a discharge port through which air is discharged from the cathode electrode;
• an injector configured to supply hydrogen gas to the anode electrode of the fuel cell;
• a circulation pump provided in a circulation path that returns the hydrogen gas discharged from the anode electrode to the anode electrode;
• and
• a controller programmed to control power generation of the fuel cell, wherein
• before a component that allows air to enter the cathode electrode when the component is removed,
• the controller is programmed to execute the following steps:
• a first step of opening the outlet valve, driving the compressor, and supplying air to the cathode electrode;
• and
• a second step of driving the circulation pump to cause hydrogen gas that remains inside the anode electrode and the circulation path to be circulated in a state in which the hydrogen gas is not supplied to the anode electrode from the injector.