| Abstract |
Three-level converters like the Active-Neutral-Point-Clamped type can suffer from series short-circuit failures. These cases cannot exist for the standard two-level converter except when a series connection of modules is used to increase the voltage rating. Even then, the course of the short circuits differs in some aspects due to the different structures of the converters. A series short-circuit scenario consists of two IGBTs and / or diodes, a freewheeling diode and the shorted module. It leads to different variantsof failure types and semiconductor stresses in comparison to a two-level converter. The behavior of thefaults is derived from equivalent circuits and proven by measurements on a three-level converter equipped with state-of-the-art 3.3 kV-IGBT modules including diodes. Some of the series short circuitsare yet described for the Neutral-Point-Clamped converter, but not in total for the active one. The presented investigations within this paper examine the origin, the possible trends of voltage and current as well as possible secondary failure cases. |
