An efficient Grid tie Solar PV based Single Phase Transformer less Inverter on common mode voltage analysis

The paper presents common mode voltage analysis of single phase grid connected photovoltaic inverter. Many researchers proposed different grid tie inverters for applications like domestic powering, street lighting, water pumping, cooling and heating applications. Traditional grid tie PV inverter uses either a line frequency or a high frequency transformer between the inverter and grid. The transformer provides galvanic isolation between the grid and the PV system but it also offers large inductive reactance to the grid which intern results in increased impedance of line. In order to increase the efficiency, to reduce the size and cost of the system, the effective solution is to remove the isolation transformer but it leads to appearance of common mode (CM) ground leakage current due to parasitic capacitance between the PV panels and the ground. The common mode current reduces the efficiency of power conversion stage, affects the quality of grid current, deteriorate the electric magnetic compatibility and give rise to the safety threats. In order to eliminate the common mode leakage current in Transformerless PV system, the proposed converter utilizes two split ac-coupled inductors that operate separately for positive and negative half grid cycles. This eliminates the shootthrough issue that is encountered by traditional voltage source inverters, leading to enhanced system reliability. SPWM technique and Phase disposition (PD )PWMs are implemented for common mode voltage and THD comparisons, it is observed that PD is efficient in eliminating common mode voltage and reduced THD output. The proposed system is analyzed using MATLAB/SIMULINK software.