A novel H6 topology and Its modulation strategy for transformerless photovoltaic grid-connected inverters

Abstract

With the rapid development of advanced power electronics technology and photovoltaic power systems, transformerless photovoltaic (TPV) inverters have been widely used due to the advantages in weight, size, efficiency and so on. However, there exists common-mode leakage current in TPV inverters, which should be satisfied the DIN VDE0126-1-1 standard. A novel H6 topology (H6-N) with dedicated modulation strategy for the TPV inverter is proposed to make the TPV inverter generate smaller common-mode leakage current comparing with the existed TPV inverter topologies and achieve low total harmonic distortion (THD) of output current. The common-mode voltage (CMV), common-mode leakage current and power losses of the single-phase TPV inverters with H6-N, H5 and HERIC topologies are compared respectively via simulation analysis. Finally, a universal prototype of TPV inverter using H6-N topology is built and tested to validate the effectiveness of the presented topology.