Comparative Study of Different Transformer-less Inverter Topologies for Grid-tied Photovoltaic System

Lately, interest is developing significantly on transformerless photovoltaic (PV) inverter for its small size, low cost and high efficiency compared to the inverter which has transformer. Different topologies of transformerless inverters are stated in the literature based on the leakage current characteristics. In this paper five different topologies of transformerless inverters (H5, H6, HERIC, Modified H6, OH5) have been selected for analysis. For controlling the grid current and voltage of the DC link a common controller for all the topologies has been designed based on PI controller and SPWM technique. These two techniques have been used to generate the switching pulses for the inverter switches. The simulation of all the five topologies are conducted in MATLAB/SIMULINK environment and analysis has been done. Finally, based on that a comparative study has been obtained based on the component ratings, leakage current, maximum efficiency and components number to determine a better topology for real world operation.