Open-circuit fault-tolerance in multilevel inverters with reduced component count

High component count and subsequent effects on volume and reliability have been the major concerns for practical applications of multilevel inverters (MIs). Recent emergence of the so-called reduced component count MIs (RCC-MIs) has been driven by the attempts to reduce the number of power switches for multilevel power conversion. In many of such topologies, the aspect of fault tolerance has not been given full consideration. In this work, some of the recently proposed RCC-MI topologies have been considered and analyzed in the light of imparting fault tolerance capability in the case of open-switch failure of any one of the power switches. In an RCC-MI, the occurrence of an open-circuit fault in a power switch would often lead to shut down due to the lack of redundant switching states. To overcome these occurrences, an optimal addition of power switches is described in this work so that the desired redundant states can be synthesized. The modified RCC-MI topologies so obtained have been analyzed under the normal and faulty conditions and computer simulations have been carried out using MATLAB/Simulink, and corresponding results have been presented. The results so obtained are experimentally validated to prove the feasibility of the proposed fault-tolerant topologies.