Photovoltaic H6-type transformerless inverter topology

Abstract

The concept of transformerless inverters has become a future trend for single phase photovoltaic grid — tied systems. The major factor to be considered while employing transformerless inverters in such applications is the leakage currents. The lack of transformers in inverters, implemented between PV panel and grid results in a galvanic connection and thus there arises problems due to leakage currents. This paper deals with an H6 transformerless full-bridge inverter topology with low leakage currents that can be used in PV grid tied applications. This H6 inverter topology is taken as an example for detail analysis with operation modes and modulation strategy. A closed loop has been developed for maintaining the voltage constant at the grid side irrespective of changes in the input voltage. Aforementioned transformerless topology is simulated for evaluating the performances in terms of power efficiency and leakage currents characteristics and a prototype for the H6 inverter topology is also built.