Transformerless Hybrid Converter With AC and DC Outputs and Reduced Leakage Current

In photovoltaic (PV) generation systems, due to the property of high efficiency, compactness, and low costs, transformerless hybrid converters with AC and DC outputs have become popular in recent times. However, common mode leakage current occurs in these converters when the converter neutral point is grounded or it is tied to the grid. The presence of leakage current causes considerable safety and electromagnetic interference (EMI) problem along with improper operation of safety devices. This paper proposes a transformerless hybrid converter capable to give simultaneous AC and DC outputs with reduced leakage current for PV system. In order to ensure reduced leakage current for all operating states (power, shoot-through, and zero) of the proposed converter, a novel pulse width modulation switching scheme is also introduced in the paper. As the proposed hybrid converter can provide both DC and AC outputs, it can supply both DC and AC loads simultaneously. Detailed steady state analysis and dynamic modeling of the proposed hybrid converter is carried and discussion on the developed PWM technique for reducing the leakage current is presented in the paper. A comparative analysis between the proposed and the conventional converters is also carried out. The performance of the proposed algorithm is validated through experimental results.