Open Circuit Fault Detection and Localization in Modular Multilevel Converter

Modular multilevel converters (MMCs) have become attractive since being proposed for high voltage/power applications with their properties such as scalability, efficiency, redundancy and high quality output voltage and current. MMCs are comprised of many submodules which are typically made of insulated gate bipolar transistors (IGBTs) and diodes in the form of half-bridge cell and failure of these switches can be a major system operation and reliability issue. In this study, detection and localization of the submodule IGBT's open-circuit fault is investigated using a 5-level MMC model. Phase shifted pulse width modulation, circulating current suppression controller and voltage sorting-balancing algorithm are applied to get proper results in open loop condition. The proposed method is validated using Matlab/Simulink computer simulations.