Open AccessGround Leakage Current Analysis and Suppression in a 60-kW 5-Level T-Type Transformerless SiC PV Inverter
Author(s) -
Lu Wang,
Yanjun Shi,
Yuxiang Shi,
Ren Xie,
Hui Li
Publication year - 2017
Publication title -
ieee transactions on power electronics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.159
H-Index - 266
eISSN - 1941-0107
pISSN - 0885-8993
DOI - 10.1109/tpel.2017.2679488
Subject(s) - power, energy and industry applications , aerospace , communication, networking and broadcast technologies , components, circuits, devices and systems , computing and processing , engineered materials, dielectrics and plasmas , fields, waves and electromagnetics , general topics for engineers , nuclear engineering , signal processing and analysis , transportation
In this paper, ground leakage current suppression in a 60-kW 5-level T-type (5LT2) transformerless SiC photovoltaic (PV) inverter has been presented. The common mode (CM) equivalent circuit is analyzed based on a high frequency (HF) CM loop and a low frequency (LF) CM loop, respectively. In the 5LT2 inverter, the derived HF CM voltage (CMV) is found to have 86% reduction compared to that of a 3-level T-type (3LT2) inverter. The simulation and experiment results are provided to demonstrate the advantages of 5LT2 inverter on HF leakage current suppression. In addition, LF CMV caused by neutral point (NP) voltage oscillation has been analyzed in this paper. It is shown that the LF CMV is nearly proportional to the NP voltage oscillation. Furthermore, an LF CMV compensation method is proposed to suppress the LF CMV by 64%, which is verified by simulation and experiment results. Finally, the leakage current shows 79% reduction in the 5LT2 inverter compared to the conventional 3LT2 inverter in the experiment. A further 52% leakage current reduction is achieved by the LF CMV compensation in the 5LT2 inverter.