A common-mode leakage current mitigation for PV-grid connected three-phase three-level transformerless T-type-NPC-MLI

Neutral point Multilevel inverter (NP-MLI) built Transformerless (TL) inverter topologies and its PWM techniques research in photovoltaic (PV) generation based grid connected system is more and more engrossed for the benefit of high efficiency, reliability, and low cost. However, a common-mode (CM) leakage current is very serious issue in these inverters, which is main causes of the gird interface concern and exaggerates EMI problems. Hence, the CM leakage current must to be handled by avoiding CM voltage through inverter PWM. This paper is proposed a space vector modulation (SVM technique to mitigate the CM leakage current by selecting only mediums, and zero vector. The paper also investigated the CM leakage currents envisage and behavior for the there-phase MLI through inverter switching function, which is not discussed before. The effectiveness of the proposed PV tied gird connected TL-TNP-MLI has been verified through the MATLAB/Simulink simulation model and FPGA based experiment results for a 1.5-kW system.