A Coupling-Transformerless Voltage-Fed Active EMI Filter for Two-Stage PV Inverters

This paper presents a coupling-transformerless active EMI filter for grid-connected two-stage PV inverters. Besides the mitigation of switching-frequency components of common-mode voltage, the reduction of sizing of magnetic components is the other purpose. A voltage-fed active filter is introduced by utilizing the existing iron core of the inverter's output filter as the coupling element, which makes the overall sizing less bulky. Simulation results are given to verify the validation of the proposed concept. The high-frequency components are significantly reduced, leading to a reduction in the high-frequency leakage current to meet VDE-0126-1-1 standards. Additionally, the size of the passive EMI filter on the AC side of the two-stage PV inverters is reduced by approximately 85%.