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Journal ArticleDOI

A Novel Asymmetrical 21-Level Inverter for Solar PV Energy System With Reduced Switch Count

12 Jan 2021-IEEE Access (IEEE)-Vol. 9, pp 11761-11775

AbstractThis article presents a novel asymmetrical 21-level multilevel inverter topology for solar PV application. The proposed topology achieves 21-level output voltage without H-bridge using asymmetric DC sources. This reduces the devices, cost and size. The PV standalone system needs a constant DC voltage magnitude from the solar panels, maximum power point tracking (MPPT) technique used for getting a stable output by using perturb and observe (P&O) algorithm. The PV voltage is boosted over the DC link voltage using a three-level DC-DC boost converter interfaced in between the solar panels and the inverter. The inverter is tested experimentally with various combinational loads and under dynamic load variations with sudden load disturbances. Total standing voltage with a cost function for the proposed MLI is calculated and compared with multiple topologies published recently and found to be cost-effective. A detailed comparison is made in terms of switches count, and sources count, gate driver boards, the number of diodes and capacitor count and component count level factor with the same and other levels of multilevel inverter and found to be the proposed topology is helpful in terms of its less TSV value, devices count, efficient and cost-effective. In both simulation and experimental results, total harmonic distortion (THD) is observed to be the same and is lower than 5% which is under IEEE standards. A hardware prototype is implemented in the laboratory and verified experimentally under dynamic load variations, whereas the simulations are done in MATLAB/Simulink.

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Citations
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Proceedings ArticleDOI
21 May 2021
Abstract: Multilevel inverters (MLIs) are extremely influential in renewable energy systems, are used to convert DC power into AC. MLIs are more beneficial in comparison to the two-level conventional inverter in terms of lower total harmonic distortion (THD), lesser electromagnetic interference (EMI), increases the capability of fault tolerance, and are more efficient. The major aspect of this review article is to analyze the recent (MLI) topologies into two categories which are symmetric and asymmetric configuration which contains the reduced number of switches $(\mathrm{N}_{\mathrm{S}\mathrm{W}})$. currently, Researchers have an eye on the using reduced number of components in MLI topologies for lesser voltage stress and high efficiency. Performance parameters such as total standing voltage (TSV), THD, and modulation techniques are briefly discussed in this article. furthermore, the general comparison of these topologies is depicted in tabular & graphical representation based on the required number of switches, number of the gate drivers $(\mathrm{N}_{\mathrm{G}\mathrm{D}})$, Number of dc voltage sources $(\mathrm{N}_{\mathrm{D}\mathrm{C}})$, THD, and the number of level $(\mathrm{N}_{\mathrm{L}})$ that are obtained through the multilevel inverter topologies.
Journal ArticleDOI
Abstract: The design and performance analysis of an open-ended three-phase induction motor, driven by an Infinite Level Inverter (ILI) with its speed control using scalar and direct vector control techniques are presented in this paper. The ILI belongs to an Active-Front-End (AFE) Reduced-Device-Count (RDC) Multi-level Inverter (MLI) topology. The fundamental structure of this inverter topology is a dc-to-dc buck converter followed by an H-bridge. This topology performs a high-quality power conversion without any shoot-through issues and reverse recovery problems. The performance of the proposed topology is validated using a resistive load. The THD of output voltage waveform obtained is 1.2%. Moreover, this topology has exhibited a high degree of dc-source voltage utilization. ILI considerably reduces the switching and conduction losses, since only one switch per phase is operated at high frequency, and other switches are operated at power frequency. The overall efficiency of the inverter is 98%. The speed control performance of the ILI topology using three-phase open-ended induction motor has been further validated through scalar and direct vector control techniques. Results obtained from simulation studies are verified experimentally.
Journal ArticleDOI
Abstract: Active filters based on multicellular inverters are an efficient, robust, and reliable means of large-scale photovoltaic systems for the next generation of smart grids. This paper presents active filters based on a cascaded multicellular inverter for three-phase PV systems connected to the North Cameroon interconnected grid. The proposed system consists of the boost chopper connected to the grids, via the 7-level inverters located before the multicellular active filters with five switching cells per arm. The contribution of this paper is due to the improved P&O MPPT algorithm for the extraction of the maximum power produced by the PV generators and the appropriate choice of the active filters to reduce the harmonic distortion rate to an acceptable value by the grid regulations for a decentralized generation. After synchronization of the system with the electrical grids, the voltage and current of the grid remain in phase. This means that the power factor is corrected. The results show that the system can reduce the harmonic distortion from 23.06% to 0.42% when the active power of the photovoltaic generators is injected into the electrical grids.
Proceedings ArticleDOI
07 Sep 2021
Abstract: Because of its high computation speed, shorter Because of its high computation speed, shorter design period, and higher density, the use of Field Programmable Gate Array (FPGA) has gained a lot of attention in the design and practical implementation of PWM (Pulse width modulation) techniques for MLI (Multilevel Inverter) structures. PWM techniques are designed to reduce switching losses, voltage stress of switches, total harmonic distortion (THD) and to increase the number of output voltage levels of inverter structures. This paper presents an Automatic Pulse Sequence Selector (APSS) for the Novel PWM technique by using FPGA LabVIEW software. The pulse sequence selection is done by using the sample index generated by the reference sinusoidal wave. By the automatic selection of specific pulse sequences from the sequences, the output wave of the inverter structure will be closer to the reference sinusoidal wave. The THD of the inverter output wave will be less than compared to direct feeding of those pulses to MLI structures. Using MATLAB/Simulink, a simulation study is performed on developed MLI structures for the validation of the proposed design. Comparison between the FFT analysis of these inverter structures verifies the efficacy of the design.

References
More filters
Journal ArticleDOI
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1,650 citations

Journal ArticleDOI
Abstract: Multilevel inverters have created a new wave of interest in industry and research. While the classical topologies have proved to be a viable alternative in a wide range of high-power medium-voltage applications, there has been an active interest in the evolution of newer topologies. Reduction in overall part count as compared to the classical topologies has been an important objective in the recently introduced topologies. In this paper, some of the recently proposed multilevel inverter topologies with reduced power switch count are reviewed and analyzed. The paper will serve as an introduction and an update to these topologies, both in terms of the qualitative and quantitative parameters. Also, it takes into account the challenges which arise when an attempt is made to reduce the device count. Based on a detailed comparison of these topologies as presented in this paper, appropriate multilevel solution can be arrived at for a given application.

648 citations

Journal ArticleDOI
Abstract: This paper proposes a novel maximum-power-point tracking (MPPT) method with a simple algorithm for photovoltaic (PV) power generation systems. The method is based on use of a short-current pulse of the PV to determine an optimum operating current where the maximum output power can be obtained and completely differs from conventional hill-climbing-based methods. In the proposed system, the optimum operating current is instantaneously determined simply by taking a product of the short-current pulse amplitude and a parameter k because the optimum operating current is exactly proportional to the short current under various conditions of illuminance and temperature. Also, the system offers an identification capability of k by means of fast power-versus-current curve scanning, which makes the short-current pulse-based MPPT method adaptive to disturbances such as shades partially covering the PV panels and surface contamination. The above adaptive MPPT algorithm has been introduced into a current-controlled boost chopper and a multiple power converter system composed of PV-and-chopper modules. Various operating characteristics have experimentally been examined on this multiple PV-and-chopper module system from a practical viewpoint and excellent MPPT performance has been confirmed through the tests.

614 citations

Journal ArticleDOI
TL;DR: It is shown that versatile stand-alone photovoltaic (PV) systems still demand on at least one battery inverter with improved characteristics of robustness and efficiency, which can be achieved using multilevel topologies.
Abstract: This paper shows that versatile stand-alone photovoltaic (PV) systems still demand on at least one battery inverter with improved characteristics of robustness and efficiency, which can be achieved using multilevel topologies. A compilation of the most common topologies of multilevel converters is presented, and it shows which ones are best suitable to implement inverters for stand-alone applications in the range of a few kilowatts. As an example, a prototype of 3 kVA was implemented, and peak efficiency of 96.0% was achieved.

524 citations