Improved single‐phase transformerless inverter with high power density and high efficiency for grid‐connected photovoltaic systems. Issue 2 (1st February 2016)

• Record Type: Journal Article
• Authors: Cho, Yong‐Won; Cha, Woo‐Jun; Kwon, Jung‐Min; Kwon, Bong‐Hwan
• Is Part Of: IET renewable power generation. Volume 10:Issue 2(2016)
• Page Start: 166
• Page End: 174
• Publication Date: 2016-02-01
• Subjects: invertors -- switching convertors -- zero current switching -- power filters -- leakage currents -- solar cell arrays -- power inductors -- power grids; high efficiency grid‐connected photovoltaic system -- high power density improved single‐phase transformerless inverter -- dual paralleled buck inverter -- auxiliary circuit -- diode zero current switching turn‐off -- lower filter inductor conduction loss -- switching loss reduction -- high switching frequency operation -- low common‐mode leakage current -- VDE‐0126‐1‐1 -- power 1 kW -- frequency 40 kHz; Renewable energy sources -- Periodicals; 333.79405
• DOI: 10.1049/iet-rpg.2015.0139
• Languages: English
• ISSNs: 1752-1416

Abstract

Abstract : This study proposes an improved single‐phase transformerless inverter with high power density and high efficiency for grid‐connected photovoltaic systems. The proposed inverter is comprised of the dual‐paralleled‐buck inverter and two auxiliary circuits for the zero‐current switching turn‐off of the diodes. The dual‐paralleled‐buck inverter and auxiliary circuits are joined by two coupled inductors. To achieve high power density, the proposed inverter operates at high switching frequency of 40 kHz. This leads to lower filter inductors and lower conduction losses of the filter inductors than conventional full‐bridge inverters. Moreover, two auxiliary circuits reduce the switching losses caused by high switching frequency operation. Furthermore, the proposed inverter provides the low common‐mode leakage current, which satisfies the criteria given by VDE‐0126‐1‐1. Thus, the proposed inverter achieves the maximum efficiency of 99%. The operation principle of the proposed inverter is analysed and verified. Experimental results for a 1 kW prototype are obtained to show the performance of the proposed inverter.