FAULT PROTECTION IN VOLTAGE SOURCE CONVERTERS WITH REDUNDANT SWITCHING CELLS VIA MECHANICAL SWITCHES BEING CLOSED PYROTECHNICALLY

摘要

A Voltage Source Converter has a series connection of switching assemblies, in which each switching assembly (7) has an electrically conducting plate member (30) carrying a plurality of semiconductor chips (31) each having at least a semiconductor device of turn-off and a free-wheeling diode connected in parallel therewith. Said chips are connected in parallel with each other by each being connected by at least one individual conductor member (35, 36) to a said plate member of an adjacent switching assembly of said series connection. Each switching assembly has a mechanical switch (39) configured to be open under normal operation of the switching assembly and configured to enable connection of said plate member of the switching assembly to the plate member of an adjacent switching assembly for bypassing said semiconductor chips of the switching assembly to which the mechanical switch belongs in the case of occurrence of a short circuit current through a semiconductor chip of the switching assembly.