DC Short-Circuit Analysis of Three-Phase Active Infeed Converters with a Power Decoupling Circuit for LVDC-Grids

Active Infeed AC-DC Converters are analyzed in terms of device and system behavior during a short circuit event at the DC-side. Taking classical circuit topologies with electrolyte DC-link capacitors in the mF range as the conventional approach, a new approach with active DC-link yielding to reduced capacitance is considered and evaluated here. Simulative as well as practical investigation are carried out to assess the potential impact on existing LVDC protective equipment. Furthermore, an emphasis is placed on the current stresses of converter freewheeling diodes which turn out to be a crucial component.