Multilevel inverters (MLIs) have developed deep roots in various industrial sectors owing to their advantages over conventional two-level inverters. However, the reliability of the semiconductor devices has been one of the major concerns for the proper functioning of MLI. Therefore, a novel fault-tolerant topology is proposed in this study. The proposed topology is capable to tolerate single-and multi-switch faults. It has lesser device count compared with the most recent work in the field. Moreover, it achieves inherent voltage balancing across capacitors. The proposed fault-tolerant topology is simulated in MATLAB/Simulink and validated experimentally. IET Power Electron. © The Institution of Engineering and Technology 2018 '↑' Voltage of the capacitor increases. '↓' Voltage of the capacitor decreases. '−' No change in the capacitor voltage.

The redundancy in switching states to generate different voltage levels is of great importance to incorporate faulttolerant features in multilevel inverters. However, this redundancy comes at the expense of high device count, which is paralleled with vulnerable characteristics of semiconductor devices, resulting in low reliability. About this concern, the present study introduces a novel fault-tolerant topology to generate the five-level output voltage. The proposed topology can tolerate open-circuit failure, for single and multiple switches with the help of novel redundant leg architecture and short-circuit condition is dealt with the fast fuses. The comparative study with recent literature is discussed, which reveals the superiority of the proposed topology, in terms of qualitative as well as quantitative parameters. Switching strategies are proposed under different single and multiple switch fault cases, which achieves self-balancing of capacitor voltage. Thus, no complex control scheme is required. The simulation is performed in MATLAB/Simulink, and the feasibility of the proposed topology is validated using experimental results.

Photovoltaic (PV) systems, especially which are installed in the remote areas, stand in need for a highly reliable system. A high failure rate of the semiconductor switches and capacitors yields a very low reliability of the inverters used in the PV system. Conventional two-level inverters are replaced by multilevel inverters (MLIs) to effectively improve the output quality waveform. However, MLIs incorporate a high device count in their architecture which further impairs the reliability of the PV system. Recent research has focused on developing fault-tolerant MLI topologies with reduced device count. However, the number of active devices and power losses, factors which are many of the times overlooked, are key in determining the reliability of the inverter. Here, the reliability of a novel fault-tolerant MLI topology is evaluated bearing in mind the effect of power losses on the junction temperature. Equal (or best) voltage source utilisation characteristics help in maintaining the uniform charge of the batteries. The concept of reliability is evaluated mathematically. The fault tolerance and even source utilisation of the proposed topology is verified through the obtained experimental results.

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