Single-phase hybrid fault-tolerant seven-level inverter

This manuscript proposes a single-phase hybrid fault-tolerant seven-level inverter for grid-connected applications. In conventional multilevel inverters, a fault in any switching device can adversely affect the output voltage levels, making the inverter unsuitable for reliable grid integration. Therefore, incorporating fault-tolerant capability is essential to ensure uninterrupted operation. In the proposed approach, fault tolerance is achieved in a cascaded H-bridge inverter by integrating a reduced-switch inverter. The developed topology comprises a reduced-switch seven-level (RSSL) inverter in combination with two cascaded H-bridge modules. A level-shifted pulse-width modulation (LSPWM) technique is employed to generate the required gating signals for the proposed inverter. Furthermore, the capacitors in the RSSL inverter maintain inherent self-voltage balancing through the adopted control strategy. The performance, suitability, and effectiveness of the proposed fault-tolerant inverter for grid-connected applications are validated through both MATLAB/Simulink simulations and experimental hardware implementation results.