A New Topology of Switched-Capacitor Multilevel Inverter With Eliminating Leakage Current

Mehdi Samizadeh,Majid Kamranian,Xu Yang,Frede Blaabjerg,Wenjie Chen,Bagher Karami

doi:10.1109/access.2020.2983654

Abstract

This paper proposes a new topology of the switched-capacitor multilevel inverter (SCMLI) for photovoltaics system, which can eliminate the leakage current. In the proposed topology, the capacitors are employed as a virtual DC power supply to boost the input voltage. Here, all capacitors are charging equal to DC source, thus, just one DC source is needed to achieve the staircase waveform. In this structure in order to make the negative levels, the capacitors are connected to the output in reverse polarity. Thus, the H-bridge circuit which is used in traditional SCMLI to build zero and negative voltage levels and leads a variable common mode voltage is removed. Due to the direct connection of the neutral terminal of the grid to the negative polarity of the PV; then this topology can eliminate the leakage current. In addition, the topology has an excellent ability to path the reverse current as well as an acceptable output waveform spectrum. The operating states of all components and loss calculations are analyzed and formulated accurately as well as simulated by using MATLAB-SIMULINK software. To confirm the performance of the proposed topology; a 500 W prototype is built and experimental results are presented.

Highlights

Nowadays, many solar energy users tend to inject their surplus energy into the grid
By considering the above-mentioned problems, this paper presents a novel switched-capacitor multilevel inverter topology, which has the potential to boost voltage as well as to eliminate the leakage current
In comparison with other switched-capacitor multilevel inverter (SCMLI) that have the potential to boost the voltage, only the proposed topology can eliminate the leakage current, and other SCMLIs suffer from this issue

Summary

INTRODUCTION

Many solar energy users tend to inject their surplus energy into the grid. The grid-connected photovoltaic systems can be divided into two different categories, with transformer and transformerless systems. In this design, the capacitor that produces the negative output voltage level sets to the input source at the zero level, and the issue of increased voltage variation, is eliminated. The capacitor that produces the negative output voltage level sets to the input source at the zero level, and the issue of increased voltage variation, is eliminated Another path is considered for the reverse current. (3) In conventional SCMLIs, the H-bridge circuit is used to generate negative output levels It will make a variable common mode voltage and lead to the leakage current. The switch S5 is eliminated in order to prevent this state

PROPOSED GENERAL SCMLI TOPOLOGY

SWITCHING LOSS

CONDUCTION LOSS

EXPERIMENTAL RESULTS

VIII. CONCLUSION