Cascaded H-bridge multilevel inverter with a fault detection scheme based on the statistic moments indexes

Multilevel inverters allow to generate AC voltages with low total harmonic distortion (THD) but requires an increased number of power switches. One of the disadvantages of that is the increased probability of a fault in one of the power switches. Thus in order to improve the reliability of the converter a fast and robust fault detection scheme must be used. In this context this paper presents a new fault detection scheme based on the AC voltages of the inverter. The proposed scheme uses fault factors that are based on the statistic moment method. This method was used for the identification of image patterns. Due to this the proposed scheme allows for a robust detection to load or voltage variations. To test the method was used a cascaded H-bridge inverter with five levels. Several tests were performed through numerical results. The use of a laboratory prototype was also used to confirm the proposed scheme.