FUEL CELL SYSTEM AND METHOD FOR OPERATING SAME

A fuel cell system (100) according to the present invention includes a stack (10); an antifreezing heater (20); a surplus power heater (30); a switching unit (40); and an electric power conversion unit (50). Where a first supply path denotes an electric power supply path from a system power supply (200) to the antifreezing heater (20), a second supply path denotes an electric power supply path from the stack (10) to the antifreezing heater (20), and a third supply path denotes an electric power supply path from the stack (10) to the surplus power heater (30), when a power failure happens, the switching unit (40) (i) disconnects the first supply path, (ii) disconnects the second supply path and connects the third supply path until an output electric power of the stack (10) is converted to the electric power necessary for operating the antifreezing heater (20), and (iii) connects the second supply path and disconnects the third supply path after the output electric power of the stack (10) is converted to the electric power necessary for operating the antifreezing heater (20).