A novel H5-D topology for transformerless photovoltaic grid-connected inverter application

Transformerless photovoltaic(TPV) grid-connected inverters have been widely used in the solar power generation systems due to the advantages in high efficiency, low cost and small size. However, because of the non-galvanic isolation configuration, the common-mode current is generated by TPV inverters due to the parasitic capacitors of between photovoltaic panels and the ground, which could result in serious security issues and electromagnetic interference(EMI) problems. In order to solve this problem, a novel H5-D topology for TPV inverter and its modulation strategy is proposed in this paper, which can completely eliminate common-mode current in TPV grid-connected power generation system by adding a clamp diode in the between the drain electrode of fifth switch and the midpoint of the dc-link to make the common-mode voltage be constant. The proposed topology will be verified by simulation with PSIM software firstly, further, the experimental prototype is also built and tested. Both simulation and experimental results verify the effectiveness of the H5-D topology on common-mode current suppression. And the proposed H5-D topology provides a good choice for TPV inverters due to its simplicity and practicality.