Three-phase eight switch inverter with reduced common mode voltage for transformerless photovoltaic systems

In grid connected photovoltaic (PV) systems transformerless inverters are widely used due to reduced size, weight and cost. However, common mode voltage reduction is one of the most key issues for transformerless PV inverters. In addition, several attractive single-phase transformerless inverter topologies have been reported to eliminate the common mode voltage based on converter topology and modulation strategy. Moreover, in literature three-phase topologies with reduced common mode voltage are not well investigated. In this paper, a novel three phase eight switch inverter (H8) and a corresponding modulation technique is proposed to reduce the common mode voltage. It is derived from the standard three-phase (H6) inverter but has different operating principles. Theoretical and performance analyses are carried out via MATLAB/Simulink to validate the effectiveness of the proposed H8 topology.