A Novel H7 Transformerless Single-Phase Inverter Topology for Leakage Current Reduction

In the case of photovoltaic inverters connected to the electrical grid, a transformer is used for reasons of galvanic isolation and adjustment of the voltage level between the input and output. However, the presence of the transformer causes a reduction in the efficiency of the system and an increase in the volume of the converter. Therefore, there is a trend in the development of transformerless grid-connected inverters. Due to the way PV modules are constructed, an equivalent stray capacitance is formed between the PV cells and their grounded structure during their operation (due to regulatory safety requirements). Without using sophisticated topologies, the lack of galvanic isolation causes some problems, such as common mode voltages and earth leakage currents through the stray capacitances of the modules. Therefore, this article aims to present an analysis of the more traditional topologies of single-phase photovoltaic inverters connected to the electrical grid without a transformer, as well as the proposal of a new topology in PSIM and MATLAB/SIMULINK simulation environment