A control apparatus for a DC converter of an electric drive system and method of operating a DC-DC converter

The invention relates to a control device (7) for controlling a DC-DC converter (6), with a voltage control device (20) which is adapted as a control variable, the output voltage (UA) of the DC-DC converter (6) to regulate, and a flow control means (30), which is adapted as a control variable output current (IA) of the DC-DC converter (6) to control, wherein the control device (7) is adapted to receive a mode selection signal (4a), and in response to the mode selection signal (4a), the voltage regulating device ( set 20) such that the voltage control means (20) the output voltage (UA) of the DC converter (6) (to a predetermined constant maximum voltage UM) limited and the flow control means (30) set such that as the control deviation (the difference between a predetermined target output voltage US) and the output voltage (UA) of the DC-DC converter (6).