Design and Analysis of Reduced Switch Single-Stage Single-Phase Common Ground Type Five-Level Photovoltaics Transformerless Inverter

This paper presents a common ground type (CGT) transformerless inverter integrated with a photovoltaic (PV) system. The design highlights the aim to eradicate the problem of common-mode voltage (CMV) and leakage current. A suitable level-shifted pulse width modulation scheme (LS-PWM) is adopted to develop the switching scheme for the inverter. The proposed topology needs only seven switches, two capacitors, and a DC link integrated to PV system. Also, the capacitors in the proposed topology are balanced using a voltage sensor to maintain the exact potential for each voltage level. A suitable controller is designed along with an LC filter for grid integration of PV fed transformerless inverter. The simulation is performed on the MATLAB/Simulink platform for 750 W system. Later, the real-time experiment is performed at 750 W for unity power factor, leading, and lagging power factor. The experiment is also performed at 160 W for low power application. The maximum blocking voltage across any switch is equal to the input source voltage. This guarantees the inverter safe operation for a high-power application. The inverter efficiency is 92.6% at 750 W on an experimental prototype. The FFT analysis shows the experimental THD for five-level inverter voltage to be 34.65%, grid voltage to be 2.51%, and grid current to be 2.29% which facilitates the feasibility of the proposed CGT transformerless inverter.