A Limited Common-Mode Current Switched-Capacitor Multilevel Inverter Topology and Its Performance and Lifetime Evaluation in Grid-Connected Photovoltaic Applications

Hossein Khoun Jahan,Mehran Sabahi,Tohid Rahimi,Lei Ding,Rasoul Shalchi Alishah,Reyhaneh Eskandari,Kent Bertilsson,Frede Blaabjerg

doi:10.3390/en14071915

Abstract

In this paper, a switched-capacitor multilevel inverter with voltage boosting and common-mode-voltage reduction capabilities is put forth. The proposed inverter is synthesized with one-half bridge and several switched-capacitor cells. Due to the voltage boosting and common-mode current reduction features, the proposed multilevel inverter is suitable for grid-connected PV applications. In addition, an analytical lifetime evaluation based on mission profile of the proposed inverter has been presented to derive lifetime distribution of semiconductors. Whereas in the proposed inverter, any components failure can bring the whole system to a shutdown. The series reliability model is used to estimate the lifetime of the overall system. The performance of the suggested multilevel inverter in grid-connected applications is verified through the simulation results using the grid-tied model in Matlab/Simulink. Moreover, the viability and feasibility of the presented inverter are proven by using a one kW lab-scaled prototype.

Highlights

Solar energy has gained more attention since it is clean, emission-free, and easy to install
In order toResults assess of theGrid-Tied performance of the suggested structure in grid-tied PV appliIn order to assess performancethat of the suggestedinstructure
2, it was tested in MatMatlab/Simulink by assuming various loading conditions

Summary

Introduction

Solar energy has gained more attention since it is clean, emission-free, and easy to install. The voltage produced by these resources is low and requires a voltage booster stage, either a dc-dc stage or a transformer [1]. In photovoltaic (PV) grid-connected inverters for safety issues, a line frequency transformer or a high-frequency transformer is used to ensure the galvanic isolation within the utility grid and PV array and to boost the input voltage. The line frequency transformers are bulky and have low efficiency and high cost. High-frequency transformers have lower volume, weight, and cost but require extra power stages and extra elements that complicate the system and, more importantly, impair inverter efficiency [2]. To increase efficiency and power density and reduce cost and weight, transformers are excluded from PV systems

Results

Discussion

Conclusion