A Novel Open-Transistor Fault Detection Method in Symmetric Cascaded H-bridge Multilevel Inverter

The increased components requirement to realize multilevel inverters (MLIs) fallout in a higher prospect of fault due to power semiconductor switches. Efficient fault detection and diagnosis (FDD) strategies have to be implemented to guarantee protection as well as the reliable operation of MLIs. This paper presents a novel open-transistor fault detection method in a charge balanced symmetric cascaded H-bridge (CHB) MLI. The method has been formulated based on the simulations and experiments on a charge balanced 5-level CHB-MLI. The proposed method uses the mean value of the bridge voltages as the diagnostic variable. The simulation and experimental results prove that this approach can detect the open-transistor fault and identify the faulty switch pair.