Analysis of the Robustness of Transformerless PV Inverter Topologies to the Choice of Power Devices

Transformerless topologies are employed in single-phase photovoltaic inverter converters due to their small size and low weight. Avoiding the grid-side transformer requires the modulation technique and the basis topology to be accordingly changed in order to mitigate dc current components in the grid side and the leakage current to ground. This paper carries out a sensitivity analysis of the selected transformerless topologies. This analysis investigates the impact of parameter variations depending on the choice of the employed semiconductor devices and detects the device for each topology, which affects the overall efficiency the most as well as the topology that is affected the most by the parameter variations with respect to the efficiency, leakage current, and grid-side dc current component. It is shown that, based on the proposed statistical analysis procedure, the impact of parameter variability can be analyzed with a reduced computational burden. An approach for the simplification of the comparison of the analyzed topologies is presented. As a result, relevant information for engineers selecting the most suitable power devices for the implementation of a certain transformerless topology is provided. The proposed analysis also allows to assess the robustness of the topologies' performance to the choice of different components when this selections is driven by other factors, such as cost and supply chain management.