A Semi-Two-Stage H5 Inverter with Improved Efficiency and Low Leakage Current

Abstract

A semi-two-stage transformerless PV grid-tied inverter based on H5 is proposed in this paper. By introducing the front-end Boost converter, the PV module and the output of the front-end Boost can be used as two different inputs of the H5 converter respectively. Therefore, the proposed topology can operate in a wide input range and part of the PV module power can be transmitted to the utility grid directly without being transferred through the path of the front-end Boost converter. The efficiency can be higher than that of the conventional two-stage H5 inverter. A modulation strategy for this topology is presented and analyzed in detail. The common-mode (CM) voltage varies with a low frequency which results in a low leakage current. An experimental prototype is built to verify the effectiveness of the proposed topology and modulation strategy.