Comparison of single-phase H4, H5, H6 inverters for transformerless photovoltaic applications

In low-power photovoltaic systems, single-phase inverters are often used to inject the generated power into the grid. To increase the efficiency, the researchers have proposed to eliminate the transformer that connects the photovoltaic system to the grid. However, the absence of this transformer allows a leakage current to circulate through the ground, the parasitic capacitance of the photovoltaic panels and the grid transformer. Several transformerless inverter topologies have been proposed and investigated. This paper tries to experimentally compare the performance of three conversion structures derived from full-bridge inverter, i.e., inverters H4, H5, and H6, each controlled with different modulation strategies. The comparison is based on the same hardware platform, experimental set-up, and operating conditions.