Single‐stage high reliability doubly grounded nonisolated PV grid‐connected inverter

Abstract

Nonisolated PV grid-connected inverters are extensively used in renewable generation systems. However, there is a shoot-through issue in traditional voltage-source inverters and common mode leakage current (CMLC) in nonisolated PV inverters. In order to address the aforementioned problems, a single-stage high reliability doubly grounded nonisolated PV grid-connected inverter is presented. The inverter is composed of a buck converter and a buck-boost converter, which operates in the positive and negative half grid periods, respectively. Grounds of the grid and PV array are shorted to eliminate the CMLC. The sinusoidal pulse width modulation (SPWM) is adopted in the proposed inverter. The proposed inverter is a single-stage system in each half grid cycle. There is no CMLC in the proposed inverter. Voltage across all semiconductors is not affected by the intrinsic capacitors of them. In addition, the inverter does not have the shoot-through issue, which increases reliability of the inverter. Only one switch is high frequency operated in each half grid period, so efficiency of the inverter can be improved, which is 98.6%. Experimental results of a 250 W single-stage high reliability doubly grounded nonisolated PV grid-connected inverter confirm the theoretical analysis. The inverter can be used in the PV application with high reliability and no CMLC.

An improved quasi Z‐source based H5 inverter with low leakage current for photovoltaic applications

“…The section presents a comparative study of the efficiencies displayed by various single‐phase five‐level inverter topologies 18‐22 . Efficiencies of these inverters are estimated using the thermal models of the switching devices available with the PSIM software 32 . While performing these efficiency calculations, identical parametric values are used across all of the converters ( V IN = 100 V, D S = 0.27, m = 0.7).…”

Topology review of doubly grounded transformer‐less single‐phase inverters

“…Since output voltage of the inverter is sinusoidal waveform, there are two polarities of the output voltage, that is, positive and negative. Therefore, the other method is that the combination of the converters with different polarity of the output voltage can be used to construct the doubly grounded inverters [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. In addition, energy storage elements, that is, flying capacitors and flying inductors, can be used to generate positive and negative constant voltage or current by semiconductors, so doubly grounded topologies using energy storage elements can be deduced [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55].…”

“…Combination of converters with different output polarity [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] Since output voltage of the inverter should be bidirectional, the doubly grounded inverters can be constructed by combining converters with different output polarity. The traditional positive output converters are the buck converter, cascaded boost-buck converter, SEPIC converter, ZETA converter etc.…”

A Thermal Management Strategy for Inverter System Based on Predictive Control

“…Under the guidance of "emission peaking and carbon neutrality goals", wind energy, solar energy and other new energy types are developing fast in China these days. Gridconnected inverters play an important role in electricity generation using various energy sources, so they have been widely used in the field of power generation [1][2][3][4][5][6], and their reliability is very important for stably and reliably merging the generated electricity in to the large power grid [7][8][9][10][11]. IGBT module is one of the most widely used power switching device in various power converters, and its reliability determines the reliability of grid-connected inverters [12][13][14][15][16].…”