New IGBTs and IGCTs, together with appropriate snubber and freewheeling diodes up to 5.5 kV (6.5 kV respectively), are opening up the possibility of establishing power electronics for the medium voltage level with manageable effort. Tri–level switching topologies and cascaded switching systems are the preferred architectures used here.

By Werner Bresch, Managing Director of GvA Leistungselektronik GmbH, and Dr. Henrik Siebel, Managing Director of Siebel & Scholl GmbH