Medium-frequency transformer-based double-isolated auxiliary supply for medium-voltage dc/dc converters

A converter for transferring power from a medium-voltage, MV, to a low-voltage, LV, side, comprising:

• at least one DC/AC cell configured to generate an AC voltage from a MV DC voltage, the DC/AC cell having a MV AC terminal;
• at least one AC/DC cell configured to generate a DC voltage from a LV AC voltage, the AC/DC cell having a LV AC terminal;
• a magnetic core;
• a LV winding wound around the magnetic core and having a LV winding terminal, the LV winding terminal connected to the LV AC terminal of the at least one AC/DC cell;
• a MV winding wound around the magnetic core and having a MV winding terminal, the MV winding terminal connected to the MV AC terminal of the at least one DC/AC cell;
• an auxiliary unit having an auxiliary winding wound around the same magnetic core and having an auxiliary winding terminal, the auxiliary winding terminal connected to control auxiliary circuits configured to operate the MV DC/AC cell;
• and
• a galvanic insulation configured to galvanically insulate the LV winding from the MV winding and the auxiliary winding,
• wherein the galvanic insulation between the LV and the MV winding and the auxiliary winding is configured to withstand the Basic Insulation Level, BIL, of the converter, of at least 10 kV.