Patent ID: 8273490

Claim:
A fuel cell system comprising: a fuel cell; a voltage converting system configured to be provided with a plurality of phases, the voltage converting system configured such that the number of active phases can be changed; a load device; and a power storage device connected to a primary side of the voltage converting system; wherein the fuel cell is connected to a secondary side of the voltage converting system, wherein the load device is connected to at least one of the primary and secondary sides of the voltage converting system, and wherein the voltage converting system is programmed to change a duty ratio of a switching pulse if a difference is caused due to a response lag between an output voltage command value commanded to the fuel cell and an actual output voltage value of the fuel cell, the fuel cell system further comprising: a detection unit that detects a system state that causes a certain amount of change or more in an output voltage command value for the fuel cell; and a prohibition system that is programmed to prohibit the voltage converting system from being driven in a predetermined number of phases or less if the system state that causes a certain amount of change or more in an output voltage command value for the fuel cell is detected.