A New Fault-Tolerant Control Method for Cascaded H-Bridge Multilevel Inverter to Increase Maximum Output Voltage

In this paper, a new fault-tolerant control algorithm for Cascaded H-Bridge Multilevel Inverter is proposed to increase the maximum available voltage under faulty conditions. In this method, once a semiconductor in a cell failed, instead of bypassing faulty cell, it is utilized to generate voltage. Since one level of faulty cell output voltage is not available, this voltage is reduced to half. However, using the proposed method, the maximum available output voltage can be increased for most of the faulty conditions in compared to the conventional fault-tolerant methods. Furthermore, the switching technique for faulty cell is modified to improve the output voltage quality. Finally, the proposed method performance is compared to the Neutral Shift method for all possible faulty conditions. Simulation results confirm effectiveness of the proposed method in increasing the maximum output voltage.