Five-Level Transformerless Inverter for Single-Phase Solar Photovoltaic Applications

Transformerless inverters are extensively employed in grid-connected photovoltaic (PV) generation systems due to its advantages of achieving low cost and high efficiency. However, the common-mode voltage issues have been motivated the proposition of new topologies, control, and modulation schemes. In common ground PV inverters, the grid neutral line is directly connected to the negative pole of the dc bus. Therefore, the parasitic capacitances are bypassed and the leakage current can be eliminated. In this paper, a five-level common ground transformerless inverter with reduced output harmonic content for PV systems is proposed. In addition, the proposed inverter can process reactive power and it presents a maximum dc-voltage utilization in opposition to half-bridge-based topologies. The operation modes of the proposed inverter, a simple modulation strategy, as well as the design guidelines are analyzed in detail. Finally, experimental results demonstrate the feasibility and good performance of the proposed inverter.