H9 and H10 Transformer-Less Solar Photovoltaic Inverters for Leakage Current Suppression and Harmonic Current Reduction

Now-a-days, transformer-less inverters integrating renewable energy resources as solar photovoltaic systems are commonly employed in many grid-connected distributed energy systems in both industrial and residential settings. Transformer-less photovoltaic (TLPV) inverters have attracted increased attention due to their unique advantages, such as increased efficiency, low cost, and ease of installation. Converting fluctuating solar dc power to consistent ac power has been a difficulty in the recent decade to avoid security risks like ground fault currents and leakage currents. Leakage current minimization is one of the most crucial factors in the TLPV inverters. Different TLPV inverter topologies have been presented in the past, with leakage current being reduced by galvanic isolation on the dc or ac side of the inverter, common mode voltage (CMV) clamping, and modulation techniques. This paper proposed two novel single-phase grid-tied TLPV inverter topologies with control blocks, which can handle a wide variety of grid voltages. The proposed TLPV inverters offer very small leakage current, reduced total harmonic distortion (THD), and improved power quality. Based on the number of semiconductor devices, the proposed inverters are termed as H9 and H10 inverters. The switches are controlled using the unipolar sinusoidal pulse width modulation, which results in constant common mode voltage and reduction in leakage currents to 11.09 and 11.73 mA for the proposed H9 and H10 inverters, respectively. The proposed H9 and H10 inverters minimize the THDs to 1.62 and 2.09%, respectively. Besides, the proposed H9 and H10 inverters exhibit 98.19 and 98.12% European efficiency. The simulations are carried out on MATLAB/Simulink and the results are experimentally validated using downscale laboratory test platforms