TECHNICAL FIELD

The invention relates to a method for operating a fuel cell system for a motor vehicle.

BACKGROUND

In fuel cell systems, oxygen from the environment is typically used as the oxidant to react with hydrogen in the fuel cell to become water and thus to provide electrical power through electrochemical conversion. During this process, the fuel cell produces extra thermal energy, which has to be discharged via a cooling system.

Prior Art

A tempering device for tempering a fuel cell stack is known from EP 2 287 952 B 1.

The underlying idea of the invention is that a fuel cell must be operated at a specific, as much as possible constant, operating temperature to achieve a particularly good efficiency for the fuel cell. The operating temperature is dependent on the type of fuel cell. If the fuel cell overheats, the output of the fuel cell must be limited. Therefore, sufficient cooling during operation is important. On the other hand, if the fuel cell starts operation at low temperatures, which is called a cold start, the fuel cell will only deliver a low output, since the electrochemical reaction and thus the voltage of the fuel cell are strongly temperature-dependent. Therefore, the temperature of the fuel cell must be increased fast upon cold starting.

It is therefore the object of the present invention to provide a method for operating a fuel cell system for a motor vehicle with which the fuel cell system can be operated in an energy efficient and economical manner.

