Comparative study between single-phase transformerless PV inverters in terms of conducted EMI

Recently there has been an increasing interest in transformerless photovoltaic (PV) inverters because of their salient benefits such as lower cost, smaller volume as well as higher efficiency as compared to those with transformer. However, a higher leakage current will inherently flow from the PV array to the grid through the stray capacitance. The leakage current increases the losses as well as the conducted and radiated electromagnetic interferences (EMI). Therefore, leakage current minimization is a key parameter to consider for the design and control of such a type of transformerless inverters. To overcome this issue, a variety of modified PV inverters topologies have been proposed with the aim to minimize the variation of the common mode voltage (CMV) that is the main source of this leakage current. However, the evaluation of their performances in terms CEM criteria has never been done before this work. Therefore, the main objective of this paper is to carry out a comparative study between three recent single-phase PV inverters topologies in terms of common mode and differential mode conducted disturbances.