Method for operating a high-voltage on-board power system of a motor vehicle, and high-voltage on-board power system

1. A method for operating a high-voltage on-board power system of a motor vehicle, comprising:

a) generating a coupling signal for coupling a fuel cell of the motor vehicle to the on-board power system, and/or a decoupling signal, by which the fuel cell is decoupled from the high-voltage on-board power system, wherein the coupling signal and/or the decoupling signal trigger adjustment of an operating voltage of the high-voltage on-board power system;

b) activating the fuel cell;

c) determining a current operating voltage of the fuel cell;

d) adjusting the operating voltage of the high-voltage on-board power system decoupled from the fuel cell to the current operating voltage of the fuel cell; and

e) coupling the fuel cell directly to the high-voltage on-board power system.

2. The method as claimed in claim 1 , wherein the fuel cell is coupled to the high-voltage on-board power system in step e) by a fuel cell connection switch.

3. The method as claimed in claim 2 , wherein the fuel cell connection switch is opened before the fuel cell is activated in step b).

4. The method as claimed in claim 1 , wherein the operating voltage of the high-voltage on-board power system is reduced in step d) to adjust it to the operating voltage of the fuel cell.

5. The method as claimed in claim 1 , wherein the steps a) to e) are carried out in the specified order.

6. The method as claimed in claim 1 , wherein the operating voltage of the fuel cell and/or the operating voltage of the high-voltage on-board power system is increased after coupling the fuel cell in step e).

7. A method for operating a high-voltage on-board power system of a motor vehicle, comprising:

a) generating a coupling signal for coupling a fuel cell of the motor vehicle to the on-board power system;

b) activating the fuel cell;

c) determining a current operating voltage of the fuel cell;

d) adjusting an operating voltage of the high-voltage on-board power system decoupled from the fuel cell to the current operating voltage of the fuel cell; and

e) coupling the fuel cell directly to the high-voltage on-board power system,

wherein a decoupling signal is generated after coupling the fuel cell, and the operating voltage of the high-voltage on-board power system is adjusted to the current operating voltage of the fuel cell in response to the decoupling signal, wherein the fuel cell is operated in a de-energized state after the adjustment, the fuel cell being decoupled from the high-voltage on-board power system in de-energized operation.

8. A high-voltage on-board power system for a motor vehicle, comprising:

a high-voltage battery; and

a fuel cell,

the high-voltage battery being connected to an inverter of an electric traction unit of the motor vehicle via a DC voltage converter,

wherein the fuel cell is directly electrically connected to the inverter,

wherein the high-voltage on-board power system is configured to adjust an operating voltage of the high-voltage on-board power system to an operating voltage of the fuel cell, and

wherein the high-voltage on-board power system has a control unit, which is configured to generate a coupling signal, by which the fuel cell is coupled to the high-voltage on-board power system, and/or a decoupling signal, by which the fuel cell is decoupled from the high-voltage on-board power system, and wherein the coupling signal and/or the decoupling signal trigger the adjustment of the operating voltage of the high-voltage on-board power system.

9. The high-voltage on-board power system as claimed in claim 8 , wherein a fuel cell connection switch is arranged between the fuel cell and a power connection point of the high-voltage on-board power system, and the power connection point is directly electrically connected to the DC voltage converter, the inverter and the fuel cell connection switch.