A Low Leakage Transformer-less 3-Level DC-DC Boost Converter for Transformer-less PV Inverters

In this paper a modification for a conventional 3-level DC-DC buck-boost converter is proposed for photovoltaic applications, to eliminate the problem of leakage current which is associated with this converter. With this modification it is possible to interface the proposed transformer-less converter with transformer-less PV inverters without any galvanic isolation requirement from the grid. This transformer-less converter is also suitable to interface PV source with grounded DC micro-grids. The proposed converter has low leakage current and retains the advantage of high efficiency due to its lower voltage stress on switching devices, which is similar to conventional 3-level DC-DC converter. Common mode voltage analysis and simulation is done to verify the proposed topology. The proposed scheme is verified on a laboratory prototype and the results are provided.