A Nine-Level Common-Ground-Type Boost Inverter for PV Applications

Transformer-less multilevel inverters (TLMLIs) are widely used in solar photovoltaic (PV) applications because they are cheap, have a higher power density, have a lower dv/dt, and are more efficient. However, the primary concern about TLMLIs is the ground leakage current due to the presence of PV parasitic impedance and the absence of galvanic isolation between grid neutral and PV. This article proposes a nine-level double boost (9L2B) common ground type inverter topology with near zero leakage current using the concept of switched capacitors (SCs). The voltages across the SCs are self-voltage balanced using the series-parallel technique, eliminating the need for a complex control circuit and sensors. Furthermore, a detailed comparative analysis against similar topologies highlights the proposed topology's benefits, such as reduced switch count, leakage current elimination, lower total standing voltage (TSV), least average number of conducting switches, self-voltage balancing, and boosting features. Finally, the feasibility and operation of the proposed topology are validated by performing experimental tests, and the results are presented.