摘要 |
A high-precision gas leak judgment comparable to that when the fuel cell is operating normally is achieved even when a fuel cell is restarted. A gas leak judgment unit (for example ECU 13) for judging gas leak in a closed space formed in a fuel gas system refers to a gas leak judgment value based on pressure change in the closed space detected by a pressure sensor to judge gas leak and, in addition, varies the fuel gas leak judgment level in response to nitrogen concentration in a fuel electrode. The varying of gas leak judgment level in response to the nitrogen concentration takes into account a temporary rise in the nitrogen concentration in the fuel electrode that occurs when a fuel cell stack is restarted and, in this case, it is preferable that the gas judgment value be altered in response to the nitrogen concentration. |