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

Abstract

In photovoltaic (PV) generation systems, due to the 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 problem along with the 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 the PV system. In order to ensure the reduced leakage current for all operating states (power, shoot through, and zero) of the proposed converter, a novel pulsewidth modulation (PWM) switching scheme is also introduced in this paper. As the proposed hybrid converter can provide both dc and ac outputs, it can supply both dc and ac loads simultaneously. The 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 this paper. A comparative analysis between the proposed and conventional converters is also carried out. The performance of the proposed algorithm is validated through experimental results.