Modular Multilevel DC/AC converter comprising a series connection of DC/AC inverter sub-modules with a central discharge apparatus

摘要

The power converter circuit (4) has two sub-modules (22) which are connected in series, for drawing electrical power from a power source (8) emitting the direct current (DC) voltage (16) through an inductor (10). Each sub-module has a single-phase half bridge (40) on input side and single-phase full bridge (42) on load side. The half bridge and full bridge are connected in parallel to intermediate circuit capacitor (44) on DC voltage side. A discharging circuit (62) for discharging the intermediate circuit capacitors of sub-modules is connected in parallel with the series circuit. Independent claims are included for the following: (1) method for selectively discharging DC link capacitor in sub-module; and (2) control device for selectively discharging DC link capacitor in sub-module.