Abstract: The disclosure relates to a fuel cell system comprising a fuel cell stack for providing an electrical power Pstack depending on a power demand, at least one auxiliary unit for operating the fuel cell stack with an electrical power consumption Paux, at least one consumer with an electrical power request Puse, and a control unit for regulating the power demand as well as a method for controlling such a fuel cell system. It is provided that the control unit is configured to selectively operate the fuel cell system in a first operating mode or in a second operating mode, whereby the fuel cell stack is turned off depending on the operating mode upon the falling below of an optimal efficiency degree operating point P(?max) of the fuel cell system or a minimum operating point Pmin of the fuel cell stack. In particular, at least one auxiliary unit is also turned off in the first operating mode, when the optimal efficiency degree operating point decreases.

Abstract: A vehicle-electrical-system assembly and a method for operating a vehicle electrical system of an electrically drivable transportation unit. The method includes determining a present electrical power consumption of a component having dynamic power-consumption behavior at a first time, providing a base value by smoothing the power-consumption behavior over time, defining a power reserve for the component by adding a static power offset to the base value, and limiting a vehicle-electrical-system power available for a traction machine of the transportation unit to provide the defined power reserve for the component.

Abstract: The disclosure relates to a fuel cell system comprising a fuel cell stack for providing an electrical power Pstack depending on a power demand, at least one auxiliary unit for operating the fuel cell stack with an electrical power consumption Paux, at least one consumer with an electrical power request Puse, and a control unit for regulating the power demand as well as a method for controlling such a fuel cell system. It is provided that the control unit is configured to selectively operate the fuel cell system in a first operating mode or in a second operating mode, whereby the fuel cell stack is turned off depending on the operating mode upon the falling below of an optimal efficiency degree operating point P(?max) of the fuel cell system or a minimum operating point Pmin of the fuel cell stack. In particular, at least one auxiliary unit is also turned off in the first operating mode, when the optimal efficiency degree operating point decreases.

Abstract: A vehicle-electrical-system assembly and a method for operating a vehicle electrical system of an electrically drivable transportation unit. The method includes determining a present electrical power consumption of a component having dynamic power-consumption behavior at a first time, providing a base value by smoothing the power-consumption behavior over time, defining a power reserve for the component by adding a static power offset to the base value, and limiting a vehicle-electrical-system power available for a traction machine of the transportation unit to provide the defined power reserve for the component.