Integrated common and differential mode filter applied to a single-phase transformerless PV microinverter with low leakage current

This paper proposes an integrated common and differential mode filter with passive damping for single-phase grid-connected transformerless photovoltaic (PV) microinverters, employing the full-bridge voltage source inverter (VSI) topology with continuous unipolar modulation. This strategy achieves low current distortion, low leakage current and high efficiency. A design procedure for the proposed filter is presented including the passive damping components. The effectiveness of the proposed solution is confirmed by simulation and experimental results. Additionally, discussions about safety standards, analysis of leakage current production mechanism and some common mode (CM) filter implementations found in the literature are presented.