Six-Switch Step-Up Common-Grounded Five-Level Inverter With Switched-Capacitor Cell for Transformerless Grid-Tied PV Applications

Abstract

Photovoltaic (PV) string inverters with transformerless grid-connected architecture are the most commonly used solar converters owing to their appliancefriendly and cost-effective benefits. A novel circuit configuration for these converters is presented in this study, which seeks to address the shortcomings of most of the conventional topologies such as the problem of leakage current, voltage ratio transformations, and power quality. The proposed structure is based on the seriesparallel switching conversion of the switched-capacitor (SC) cell and is comprised of only six unidirectional power switches with a common-grounded (CG) feature. Through the use of the SC cell and the CG connection of active and passive used elements, not only is the number of output voltage level enhanced by up to five but also a two times voltage boosting feature with a single stage operation as well as elimination of the leakage current is acquired. Herein, to inject a tightly controlled current into the grid, a peak current controller approach has been used which can handle both the active and reactive power supports modes.Theoretical analysis, design guidelines, comparative study, and some experimental results are also given to corroborate the feasibility and accurate performance of the proposed topology.

A Novel Common-Ground-Type Nine-Level Dynamic Boost Inverter

“…In recent literature, the common-ground-type inverters have seen evolution in terms of their simultaneous achievement of 5-level voltage generation and double voltage gain [17]- [19]. Further enhancement in the voltage levels generation, such as 7-level and 9-level topology is also presented in [20] (Fig.…”

“…1. Existing multilevel inverter with common ac and dc ground presented in: (a) [12], (b) [13], (c) [14], (d) [15], (e) [16], (f) [17], (g) [18], (h) [19], (i) [20], and (j) [21] (the common ac and dc ground is located at dc source positive terminal instead of negative terminal in all other topologies). II.…”

Hybrid bypass technique to mitigate leakage current in the grid-tied inverter

“…Due to common grounding the leakage current is reduced and also it has reduced harmonics. Another similar type of five-level inverter with series parallel switching conversion and common ground technique is proposed in [23]. The main advantage of the inverter is, with only one stage it was able to output five-levels and also enhanced the output voltage.…”

Switched-Capacitor-Based Five-Level T-Type Inverter (SC-5TI) With Soft-Charging and Enhanced DC-Link Voltage Utilization

“…However, the number of ac voltage levels remains 3 despite the use of two capacitors. In the recent literature, the commonground inverters have seen evolution in terms of their simultaneous achievement of 5-level generation and double voltage gain [23]- [25]. In all common-ground-type SC-MLIs, the dc source is excluded from supplying the load during the negative voltage levels.…”