Fault Detection on Multicell Converter Based on Output Voltage Frequency Analysis

Multilevel converters uses a large amount of semiconductors. This allows to reconfigurate the converter to work even on internal fault condition. This paper presents a method to detect faulty cells in a cascaded multicell converter requiring just one voltage measurement per output phase. The method is based on high frequency harmonic analysis, using a dynamic prediction of their behavior, avoiding false detection on transients while keeps the precision under fault events. Once the faulty cell is detected, it can be short-circuited allowing the converter to keep working according to previously reported techniques