Improved Dual-vector Model Predictive Control for Common-mode Voltage Constant on a Grid-connected Inverter

Fenyang  Gao; Zhilong  Shi; Kaiwen Yang, Yarong  Pan; Zhishan  Gao; Hao  Xu; Yaxin  Qiang

doi:10.6180/jase.202502_28(2).0009

Improved Dual-vector Model Predictive Control for Common-mode Voltage Constant on a Grid-connected Inverter

Fenyang Gao, Zhilong ShiThis email address is being protected from spambots. You need JavaScript enabled to view it., Kaiwen Yang, Yarong Pan, Zhishan Gao, Hao Xu, and Yaxin Qiang

College of Automation and Electrical Engineering, Lanzhou jiaotong University, Lanzhou 730070 China

Received: July 19, 2023
Accepted: February 12, 2024
Publication Date: April 14, 2024

Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.6180/jase.202502_28(2).0009

A large amount of common-mode voltage (CMV) is generated during the operation of non-isolated photovoltaic (PV) grid-connected inverters, resulting in common-mode leakage currents (CMC) and other problems. Taking two-level four-leg inverter as the research object, a CMC suppression scheme is proposed in this paper. It establishes a common-mode loop model to analyze the relationship between the CMV and the CMC. The first three leg, inverting part, use improved double-vector model predict current control (IDV-MPCC), and the fourth leg of the inverter is used to maintain a constant CMV to achieve the suppression of the CMC, and the fourth leg is indirectly controlled by the switching state of the first three leg. Finally, the data of the CMV and the CMC under different methods are compared and analyzed by simulation to verify the method’s feasibility. The results show that the proposed strategy has constant the CMV at u_dc/2, suppresses the CMC below 210 mA, and effectively reduce the switching frequency (SF) and power loss (PL) and output current harmonic distortion rate (THD). Meanwhile, the control strategy is low in computation and fast in seeking the optimum.

Keywords: grid-connected PV system; CMV; CMC; three-phase four-leg inverter; IDV-MPCC

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