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Lookup NU author(s): Dr Mohamed Dahidah
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
This paper presents a grid-connected system for renewable energy source (RES) applications. The proposed system consists of a modified switched-capacitor (SC) based multilevel inverter and a DC-DC flyback converter. By using the DC-DC isolated converter the voltages of DC-link capacitors (C1 and C2) are adjusted to the same values. Therefore, a symmetric structure is made which can produce a 17-level output voltage waveform. Unlike previously introduced topologies in the same class, the modified SC-based multilevel inverter has many benefits like limited capacitor charging spike, reasonable size, power density, cost per output power, active and reactive power support, adjusted injected current to the grid, and reduced number of input power DC supplies. In the modified structure two isolated DC sources are generated using an isolated DC-DC flyback converter to supply the SC-based inverter and also increased the number of voltage levels produced at the output. In the modified grid-tied system, by adjusting the turns ratio of the used transformer and also the duty cycle of the isolated DC-DC converter, it is possible to provide flexible voltage boosting performance. In fact, to provide this feature, there are two degrees of freedom such as duty cycle and transformer turn ratio. In the modified topology, one of the most important problems of the switched capacitor, i.e., the occurrence of the inrush currents during charging capacitors, is solved by using a circuit unit that consists of an inductor with a parallel power diode in the capacitive charging current path. In order to verify the limitation of the capacitor charring spike feature of the modified inverter and investigate the effect of diode-inductor circuits on the capacitor’s voltage ripple, and output voltage THD, simulation results are provided by MATLAB/Simulink software. To confirm the performance of the presented structure, comprehensive experiments, and comparisons have been provided. In the experiments, the peak current control (PCC) method is applied to control both the active and reactive power injected into the grid by the modified 17-levels grid-connected inverter. Note that, the experimental prototype is built at 770W output power.
Author(s): Marangalu MG, Kurdkandi NV, Hosseini SH, Tarzamni H, Dahidah MSA, Sarhangzadeh M
Publication type: Article
Publication status: Published
Journal: IEEE Open Journal of Power Electronics
Year: 2023
Volume: 4
Pages: 579-602
Online publication date: 07/08/2023
Acceptance date: 30/07/2023
Date deposited: 04/08/2023
ISSN (electronic): 2644-1314
Publisher: Institute of Electrical and Electronics Engineers
URL: https://doi.org/10.1109/OJPEL.2023.3302282
DOI: 10.1109/OJPEL.2023.3302282
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