Method for limiting damage to a converter having power semiconductors in the case of a short circuit in the DC voltage intermediate circuit

A method for limiting damage to a converter having power semiconductors, the converter being connected to at least one further converter or at least one machine via a DC voltage intermediate circuit affected by a short circuit, wherein a drive unit is supplied with energy by an energy store of the converter or of the DC voltage intermediate circuit, which comprises the steps of:

• ascertaining, via the drive unit, a short circuit and subsequently driving at least one semiconductor protective device connected in parallel with a power semiconductor, such that a short-circuit current flows both via the semiconductor protective device and via the power semiconductor connected in parallel therewith;
• charging the energy store before the converter is connected to the DC voltage intermediate circuit;
• connecting the power semiconductor to the DC voltage intermediate circuit by means of a DC voltage switch;
• opening the DC voltage switch before the converter is connected to a supply system;
• connecting the converter to the supply system by means of AC voltage switches;
• in order to connect the converter to the DC voltage intermediate circuit, first opening all the AC voltage switches and the DC voltage switch;
• and
• afterward, in order to charge the energy stores, closing the AC voltage switches, each of the AC voltage switches is opened after charging of the energy stores, the DC voltage switch is closed for connecting the converter to the DC voltage intermediate circuit, and, finally, each of the AC voltage switches is closed to connect the converter to the supply system provided that no DC short circuit was able to be detected beforehand.