A Generalized Partial Fault-Tolerant Single-Phase Common-Ground Multilevel Inverter for PV System

The common ground multilevel inverter (MLI) is highly appreciated in transformerless photovoltaic (PV) systems, which have improved leakage current performance and reduced filter size. The fault-tolerant (FT) capability is essential in a common ground inverter to enhance the reliability of the system. This paper highlights a FT strategy for single-phase common ground MLI under different open switch fault conditions. The proposed circuit can self-balance the voltage across the switched capacitor (SC) in normal and switch open circuit (OC) fault conditions. Moreover, the employed modulation scheme enables the SCs to be connected in series or parallel to obtain a wide range of output voltages with reduced input voltage. Further, the circuit can be extended for higher voltage levels by adding SC cells. A detailed Markov reliability and cost function assessment highlights the merits of the proposed inverter over counter topologies. Finally, the inverter's operational feasibility and effectiveness are validated through 500 W prototype experimentally.