A single phase five-level inverter with single and multiple switch fault tolerance capabilities

The reliability of multilevel inverters (MLIs) is of great importance, when they are employed for applications such as aircrafts, electric vehicles, standalone, and grid connected photovoltaic (PV) system. To achieve required output voltage during post-fault scenarios, several fault tolerant topologies of multilevel inverter have been proposed. However, the primary constraints which add on a limitation to their implementation are increased device count and inability to tolerate single and multiple switch faults with the conduction of lesser or equal switches as in pre-fault case. The inability to tolerate various types of faults, such as open circuit or short circuit, cause severe impact on the system and further increase the cost. In this regard, a fault tolerant (FT) multilevel inverter topology which tolerates aforementioned faults is proposed. The proposed topology is able to withstand both single switch and multiple switch faults with equal or lesser blocking voltage. The proposed topology employs only unidirectional switches, thus increasing the reliability and reducing the cost of inverter. The proposed work is validated experimentally.