Boosting Factor Research Articles

Dual‐input step‐up switched‐capacitor multilevel inverter with reduced voltage stress on devices

SummaryThis paper proposes a single‐phase dual‐input step‐up switched‐capacitor multilevel inverter that employs three capacitors, 15 switches, and two diodes to provide 13 voltage levels and triple‐voltage boosting factor in its symmetric form and 37 levels with voltage boosting factor of 3.6 in its asymmetric version. This high boosting factor is accomplished without utilizing any transformer. For each output voltage level, there exists flow paths for both the positive and negative load current directions, which makes the proposed inverter capable of supplying any load type with variety of power factors (zero to unity). The voltage balancing of the capacitors takes place naturally, which tackles the need to auxiliary charge‐balancing circuits or control mechanisms. The proposed inverter can generate negative levels without the end‐side H‐bridge. Moreover, the voltage stress on the semiconductor devices is less than the peak output voltage. The increased number of levels and sinusoidal‐like waveform of the output voltage waveform enhances the quality and lowers the harmonic content of the load voltage and current waveforms, even for resistive loads. As the result, the load‐side filter can be downsized or removed. This paper employs the fundamental frequency method (FFM) as the switching technique, which is simple to implement and also operates the switches at low frequencies, leading to lower switching losses. The ascendancy of proposed inverter over similar counterparts has been investigated through comprehensive comparative analysis. Moreover, the correct performance of the proposed inverter at different modulation indices, and load types as well as during dynamic load changes has been verified by simulation and experimental analysis.

Unveiling the bent-jet structure and polarization of OJ 287 at 1.7 GHz with space VLBI

We present total intensity and linear polarization images of OJ 287 at 1.68 GHz, obtained through space-based very long baseline interferometry (VLBI) observations with RadioAstron on April 16, 2016. The observations were conducted using a ground array consisting of the Very Long Baseline Array (VLBA) and the European VLBI Network (EVN). Ground-space fringes were detected with a maximum projected baseline length of ∼5.6 Earth’s diameter, resulting in an angular resolution of ∼530 μas. With this unprecedented resolution at such a low frequency, the progressively bending jet structure of OJ 287 has been resolved up to ∼10 parsec of the projected distance from the radio core. In comparison with close-in-time VLBI observations at 15, 43, 86 GHz from MOJAVE and VLBA-BU-BLAZAR monitoring projects, we obtain the spectral index map showing the opaque core and optically thin jet components. The optically thick core has a brightness temperature of ∼1013 K, and is further resolved into two sub-components at higher frequencies labeled C1 and C2. These sub-components exhibit a transition from optically thick to thin, with a synchrotron self-absorption (SSA) turnover frequency estimated to be ∼33 and ∼11.5 GHz, and a turnover flux density ∼4 and ∼0.7 Jy, respectively. Assuming a Doppler boosting factor of 10, the SSA values provide the estimate of the magnetic field strengths from SSA of ∼3.4 G for C1 and ∼1.0 G for C2. The magnetic field strengths assuming equipartition arguments are also estimated as ∼2.6 G and ∼1.6 G, respectively. The integrated degree of linear polarization is found to be approximately ∼2.5%, with the electric vector position angle being well aligned with the local jet direction at the core region. This alignment suggests a predominant toroidal magnetic field, which is in agreement with the jet formation model that requires a helical magnetic field anchored to either the black hole ergosphere or the accretion disk. Further downstream, the jet seems to be predominantly threaded by a poloidal magnetic field.

Field-level Lyman-α forest modeling in redshift space via augmented nonlocal Fluctuating Gunn-Peterson Approximation

Context. Devising fast and accurate methods of predicting the Lyman-α forest at the field level, avoiding the computational burden of running large-volume cosmological hydrodynamic simulations, is of fundamental importance to quickly generate the massive set of simulations needed by the state-of-the-art galaxy and Lyα forest spectroscopic surveys. Aims. We present an improved analytical model to predict the Lyα forest at the field level in redshift space from the dark matter field, expanding upon the widely used Fluctuating Gunn-Peterson Approximation (FGPA). Instead of assuming a unique universal relation over the whole considered cosmic volume, we introduce a dependence on the cosmic web environment (knots, filaments, sheets, and voids) in the model, thereby effectively accounting for nonlocal bias. Furthermore, we include a detailed treatment of velocity bias in the redshift space distortion modeling, allowing the velocity bias to be cosmic-web-dependent. Methods. We first mapped the dark matter field from real to redshift space through a particle-based relation including velocity bias, depending on the cosmic web classification of the dark matter field in real space. We then formalized an appropriate functional form for our model, building upon the traditional FGPA and including a cutoff and a boosting factor mimicking a threshold and inverse-threshold bias effect, respectively, with model parameters depending on the cosmic web classification in redshift space. Eventually, we fit the coefficients of the model via an efficient Markov chain Monte Carlo scheme. Results. We find evidence for a significant difference between the same model parameters in different environments, suggesting that for the investigated setup the simple standard FGPA is not able to adequately predict the Lyα forest in the different cosmic web regimes. We reproduce the summary statistics of the reference cosmological hydrodynamic simulation that we use for comparison, yielding an accurate mean transmitted flux, probability distribution function, 3D power spectrum, and bispectrum. In particular, we achieve maximum deviation and average deviation accuracy in the Lyα forest 3D power spectrum of ∼3% and ∼0.1% up to k ∼ 0.4 h Mpc−1, and ∼5% and ∼1.8% up to k ∼ 1.4 h Mpc−1. Conclusions. Our new model outperforms previous analytical efforts to predict the Lyα forest at the field level in all the probed summary statistics, and has the potential to become instrumental in the generation of fast accurate mocks for covariance matrices estimation in the context of current and forthcoming Lyα forest surveys.

An assessment of the effect of gross capital formation and financial development on Renewable Energy Consumption in middle-income nations: Does FDI act as a boosting factor? Evidence from CS-ARDl and NARDL framework

The association between foreign direct investment (FDI), gross capital formation (GCF), financial development, and renewable energy usage is investigated in this research (REC). The research used the CS-ARDL and NARDL estimates to examine the correlation among REC, FDI, GCF, and financial development. The results demonstrate a strong and statistically valid positive correlation in both the immediate and prolonged periods. Whether innovation in FDI is favourable or bad, it may ultimately affect REC, either by accelerating or diminishing it. Additionally, the research emphasizes a substantial and statistically valid association between REC and GCF, demonstrating that domestic capital creation has a favourable effect on the incorporation of clean energy. Furthermore, the data demonstrates a noteworthy association between financial development and renewable energy certificates (RECs), suggesting that the financial incentivizes facilitated by financial development play a pivotal role in encouraging the widespread use of REC. The results shown in this research are consistent with prior scholarly works and have substantial ramifications for comprehending the intricate interplay of sustainable energy, foreign direct investment (FDI), gross capital formation (GCF), and financial growth. However, the research emphasizes the need to conduct a thorough assessment of the characteristics and quality of foreign direct investment (FDI) inflows. Furthermore, it emphasizes the need to promote equitable and sustainable development in the renewable energy industry while considering its impacts on society and the environment. In addition, the report highlights the possible social and environmental repercussions that may result from renewable energy initiatives sponsored locally. This underscores the importance of establishing resilient policy frameworks and efficient governance mechanisms to guarantee that financial development, foreign direct investment (FDI), and the Green Climate Fund (GCF) all contribute to fostering sustainable and equitable expansion in the utilization of renewable energy. As a result, the study's results provide significant contributions to the understanding of how to optimize the use of financial development, green climate funds (GCF), and foreign direct investment (FDI) in order to promote the adoption of renewable energy. But before formulating sustainable approaches to encourage the use of renewable energy, it is vital to do a thorough evaluation of the broader ramifications and associated variables.

Modeling and analysis of the LC filter-integrated quasi Z-source indirect matrix converter for the wind energy conversion system

A Quasi Z-Source Indirect Matrix Converter (QZSIMC) is proposed in this paper for Permanent Magnet Generator (PMG) based Direct Drive Wind Energy Conversion Systems (DDWECS) to enhance the voltage transfer ratio and also to control the output voltage under various loading conditions. The QZSIMC comprises three Quasi Z-Source (QZS) networks connected between PMG and load through a three-phase Indirect Matrix Converter (IMC). Two different PWM control techniques such as Carrier Based Pulse Width Modulation Technique and Modified Space Vector Pulse Width Modulation Technique are proposed to analyze the performance of QZSIMC. By changing the shoot through time period, the duty ratio of quasi Z-Source network can be increased which in turn increases the boost factor of both QZSIMC without affecting the efficiency of the converter. A closed-loop control system has also been designed to sustain constant parameters at the output. The proposed QZSIMC for PMG based DDWECS along with two different PWM Control Schemes are to be modeled using MATLAB/SIMULINK environment. To validate the simulation results, a 1 kW, 415 V, 50 Hz experimental setup with an FPGA SPARTAN-6 processor has been developed in the laboratory for QZSIMC and the results are investigated based on the parameters such as output voltage, output current, Switching Stress, Boost Factor, inductor current, capacitor voltage, Total Harmonic Distortion.

Milliarcsecond core size dependence of the radio variability of blazars

ABSTRACT Studying the long-term radio variability (time-scales of months to years) of blazars enables us to gain a better understanding of the physical structure of these objects on subparsec scales, and the physics of supermassive black holes. In this study, we focus on the radio variability of 1157 blazars observed at 15 GHz through the Owens Valley Radio Observatory Blazar Monitoring Program. We investigate the dependence of the variability amplitudes and time-scales, characterized based on model fitting to the structure functions, on the milliarcsecond core sizes measured by Very Long Baseline Interferometry. We find that the most compact sources at milliarcsecond scales exhibit larger variability amplitudes and shorter variability time-scales than more extended sources. Additionally, for sources with measured redshifts and Doppler boosting factors, the correlation between linear core sizes against variability amplitudes and intrinsic time-scales is also significant. The observed relationship between variability time-scales and core sizes is expected, based on light travel-time arguments. This variability versus core size relation extends beyond the core sizes measured at 15 GHz; we see significant correlation between the 15 GHz variability amplitudes (as well as time-scales) and core sizes measured at other frequencies, which can be attributed to a frequency–source size relationship arising from the intrinsic jet structure. At low frequencies of 1 GHz where the core sizes are dominated by interstellar scattering, we find that the variability amplitudes have significant correlation with the 1 GHz intrinsic core angular sizes, once the scatter broadening effects are deconvoluted from the intrinsic core sizes.

Multioutput Switched-Capacitor Multilevel Inverter With Intrinsic Elimination of the Photovoltaics Induced Leakage Current and High Boost Factor

A new multi-output switched-capacitor multilevel inverter (SCMLI) and a few trade-off solutions are proposed. It concomitantly features: a) a common input source-load ground, eliminating thus the photovoltaic cell leakage current, b) a permanent non-zero input current, c) a high boost factor, equal to that in a similar no common ground inverter, and d) the smallest number of capacitors and switches per output and per boost factor compared to their count in the available common ground SC inverters. Its basic structure is constituted by two SC sub-circuits. The originality of the proposed inverter comes from a novel operation scheme in which one of the two SC sub-circuits supplies the positive half-sinusoid of both outputs, while the other SC sub-circuit supplies the negative half-sinusoid of both outputs. The alternative solutions require a few more switches. Their new switching strategies provide an equal capacitor voltages ripple, thus leading to smaller capacitance values and less capacitor-induced losses. An original design of an input choke allows drastically reducing the input current ripple, as required in alternative energy powered applications. The new SCMLI was conceived as an inverter powered by a solar cell that supplies standalone residential ac loads of small powers. A laboratory 400W nine-level prototype is built to verify the theoretical analyses and feasibility of the proposed topology.

Design analysis and control of step‐up converter with reduced switch stress

SummaryIn light of the increasing share of renewable energy sources (RES) in electricity generation, the research community is directing their attention toward developing highly efficient DC‐DC high‐gain step‐up converters. These converters are designed to exhibit reduced voltage stress on the switching devices (semiconductors). This paper presents a comprehensive study of a switch voltage stress‐reduced step‐up converter that offers a range of additional features, including the availability of a common ground point, continuous input current, simple two‐mode continuous conduction mode (CCM) operation, wide duty cycle range, and quadratic boosting factor. To achieve the aforementioned features, the converter utilizes two switches with the same operating modes, eliminating the need for complex switching circuitry. Operational modes, steady‐state analysis, and design considerations have been presented in detail. Comparative analysis indicates that the voltage conversion ratio per number of devices in the proposed topology is significantly higher than that of similar topologies. In addition, the voltage stress of switches is considerably less than the topologies addressed in the literature. The study further includes detailed mathematical and experimental analyses, small signal analysis, and hardware implementation to support the theoretical findings. The converter's efficiency has been thoroughly analyzed along with thermal analysis to ensure its reliability.

Dual-Ground Transformerless Nine-Level Dynamic Voltage Boosting Inverter Topology

ABSTRACT This article presents a new nine-level common ground (CG) type transformerless inverter (TL) structure with an integrated boost (IB) cell. The proposed structure eliminates the leakage current due to the CG structure between the input source and the grid neutral. The proposed topology is derived by combining a DC-DC boost converter and switched capacitor (SC) cell, capable of generating the nine-level output voltage over a wide range of input voltage variations. By maintaining the duty cycle of the IB converter switch at 50%, the proposed topology generates the output voltage with a boosting factor of 4. Besides, soft charging of the involved SCs and reduced inrush current is also achieved through the inductor, which ensures the permissible current stresses of the power switches. Furthermore, the voltage across the SCs is self-balanced, eliminating the need for complex independent control techniques. A 725-W laboratory prototype is built to test the performance of the proposed topology under various operating conditions, such as input and load variations. The measured efficiency of 96.9% at 725 W is obtained and is comparable with the simulation efficiency. Finally, the merits of the proposed topology are highlighted using a detailed comparison with the other recent nine-level inverter topologies.

Machine learning-based ovarian cancer prediction with XGboost and stochastic gradient boosting models

Ovarian cancer is one of the most common types of gynecological malignancies with its high mortality rate, silent and occult tumor growth, late onset of symptoms and diagnosis in advanced stages. Therefore, the need to develop new diagnostic techniques to predict the course of the disease and the prognosis of this malignancy has increased. In this study, ovarian cancer and benign ovarian tumor samples will be classified to create an accurate diagnostic predictive model using the machine learning method XGBoost and Stochastic Gradient Boosting and disease-related risk factors will be determined. This current study considered the open-access ovarian cancer and benign ovarian tumor samples data set. For this purpose, data from 349 patients were included. The data set was divided as 80:20 as a training and test dataset. XGBoost and Stochastic Gradient Boosting were constructed for the classification via five-fold cross-validation. Accuracy, balanced accuracy, sensitivity, specificity, positive predictive value, and negative predictive value performance metrics were evaluated for model performance. Among the performance criteria in the test stage obtained from the XGBoost model that has the best classification result; accuracy, balanced accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and F1 score were obtained as 89.5%, 88.7%, 85.7%, 91.7%, 85.7%, 91.7%, and 85.7%, respectively. According to the variable importance obtained as a result of the model, the variables most associated with the diagnosis were CA72-4, HE4, LYM%, ALB, EO%, BUN, RBC, NEU, and MCV, respectively. The applied machine learning model successfully classified ovarian cancer and created a highly accurate diagnostic prediction model. The results from the study revealed effective parameters that can diagnose ovarian cancer with high accuracy. With the parameters determined as a result of the modeling, the clinician will be able to simplify and facilitate the decision-making process for the diagnosis of ovarian cancer.

The Influence of Online Communication on the English Language in Real Life

Online communication is how people communicate, connect, transact to send, retrieve or receive information of any kind via the internet using digital media. The past two decades have seen a massive development in the methods and means of online communication. From texting a friend on social media to attending an online video conference for work to shopping online from the comfort of your home, online communication has revolutionized our lives in innumerable ways. The coronavirus pandemic of the year 2020 has brought online communication to the foreground. Online communication has undoubtedly become an indispensable part of our lifestyle today. The knowledge of the English language being a prerequisite for online communication, has inevitably led to the increase in outreach of the English language as a by- product of the progress of online communication. Although several modes of online communication are available in multiple languages today, this is not true for all and despite that, a basic knowledge of the English language remains compulsory. The pandemic transformed online communication from a choice to an unignorable necessity since it was the only means of communication in the time of crisis, hence forcing increasing number of individuals to learn the English language to successfully communicate online. Even though online communication has been a boosting factor for the English language, one can also not ignore its ill effects on the language. Social media has changed the way we speak and write English including the advent of an alphabet soup of acronyms, abbreviations and neologisms which has grown up around technologically mediated communication. This paper explains how online communication has aided the spread of the English language besides exploring the many ways in which the English language has been adversely affected by online communication.

Dual Input Single Phase Quasi Z Source Inverter for Integrated Photovoltaic Systems

Globally, climate change has increased various environmental concerns, and there is a very high and still ever greater penetration of renewable energy power into energy grids. The intermittent nature of these energy sources has demanded a strong power electronic interface to maintain an uninterrupted power flow to the external load. This paper deals with a novel dual input quasi Z source inverter (qZSI) that can operate with two intermittent sources and perform a single stage power conversion. The novelty of the proposed methodology is the implementation of qZSI with a reduced number of switches, increased voltage gain, and a high boosting factor which results in increased efficiency. A simple boost control-based pulse width modulation (PWM) technique has been adopted, which has been observed after analysis, to have reduced the stress on the switches and simultaneously increased system efficiency. Perturb and observe method-based maximum power point tracking (MPPT) was integrated into the study with the control technique, and its performance was observed using MATLAB/Simulink and further validated with a scale down model.

Classification of gamma-ray targets for velocity-dependent and subhalo-boosted dark-matter annihilation

Gamma-ray observations have long been used to constrain the properties of dark matter (DM), with a strong focus on weakly interacting massive particles annihilating through velocity-independent processes. However, in the absence of clear-cut observational evidence for the simplest candidates, the interest of the community in more complex DM scenarios involving a velocity-dependent cross-section has been growing steadily over the past few years. We present the first systematic study of velocity-dependent DM annihilation (in particular p-wave annihilation and Sommerfeld enhancement) in a variety of astrophysical objects, not only including the well-studied Milky Way dwarf satellite galaxies, but nearby dwarf irregular galaxies and local galaxy clusters as well. Particular attention is given to the interplay between velocity dependence and DM halo substructure. Uncertainties related to halo mass, phase-space and substructure modelling are also discussed in this velocity-dependent context. We show that, for s-wave annihilation, extremely large subhalo boost factors are to be expected, up to 1011 in clusters and up to 106–107 in dwarf galaxies where subhalos are usually assumed not to play an important role. Boost factors for p-wave annihilation are smaller but can still reach 103 in clusters. The angular extension of the DM signal is also significantly impacted, with e.g. the cluster typical emission radius increasing by a factor of order 10 in the s-wave case. We also compute the signal contrast of the objects in our sample with respect to annihilation happening in the Milky Way halo. Overall, we find that the hierarchy between the brightest considered targets depends on the specific details of the assumed particle-physics model.

A transformer‐less high‐boosting common‐grounded multi‐phase DC–DC converter with continuous input‐current favourable for low‐power applications

AbstractThe traditional dc–dc converters have limited boosting ability. Significant voltage gains can be accomplished only at extreme duty ratios, where the high voltage/current stress and losses occur on semiconductors. This work proposes a common‐ground multi‐phase boost dc–dc converter that benefits from high boosting factor at low duty ratios, continuous input‐current and minimum operational modes (only two at CCM) regardless of number of phases. Due to the presence of common‐ground point, the proposed converter can efficiently remove the leakage current while using the PV as the input source. Also, because of multi‐phase nature, the proposed converter has low current stress on its input devices, which leads to lower voltage drops and better efficiencies. The number of phases can freely be selected based on required boosting factor or converter efficiency. To assure of proper performance of proposed converter, the three‐phase (n = 3) version has been investigated in detail and its steady‐state analysis as well as real‐gain and loss calculations have been presented. The competitiveness of the suggested converter has been verified by performing comprehensive comparative analysis. The experimental results (for n = 3) have also been provided to certify the correct performance of suggested converter.

The effect of co-opinion on the cocitation-based information retrieval systems’ effectiveness evaluated by semantic similarity

The co-opinionatedness measure, that is, the similarity of cociting documents in their opinions about their cocited articles, has been recently proposed. The present study uses a wider range of baselines and benchmarks to investigate the measure’s effectiveness in retrieval ranking that was previously confirmed in a pilot study. A test collection was built including 30 seed documents and their 4702 cocited articles. Their citances and full-texts were analysed using natural language processing (NLP) and opinion mining techniques. Cocitation values, syntactical similarity and contexts similarity were used as baselines. The distributional semantic similarity and the linear and hierarchical Medical Subject Headings (MeSH) similarities served as benchmarks to evaluate the effect of the co-opinionatedness as a boosting factor on the performance of the baselines. The improvements in the rankings were measured by normalised discounted cumulative gain (nDCG). According to the findings, there existed significant differences between the nDCG mean values obtained before and after weighting the baselines by the co-opinionatedness measures. The results of the generalisability study corroborated the reliability and generalisability of the systems. Accordingly, the similarity in the opinions of the cociting papers towards their cocited articles can explain the cocitation relation in the scientific papers network and can be effectively utilised for improving the results of the cocitation-based retrieval systems.

A new high‐level boost inverter topology with reduced device count

AbstractThe requirement of a boosting aspect for the power electronic converter is essential for the fuel cell, solar PV, and battery‐based applications as the generated voltage is of low voltage magnitude. In these low‐voltage applications, a new boost inverter topology has been suggested, where the power conversion will happen in a single‐stage instead of two‐stage (dc–dc converter + two‐level inverter). The proposed topology consists of 11 power semiconductor devices, one switched capacitor unit, and two dc voltage sources that are arranged in the magnitude of 1:3. This arrangement is able to achieve an output voltage of 15 levels with a boosting factor of 1.75. The other advantages of the designed topology have been the reduced device count with the self‐balancing of capacitor voltage and improved efficiency with better power loss sharing among the switches. By accumulating additional switched‐capacitor units to the proposed basic structure, the proposed inverter can be extended to support a greater number of levels and a higher voltage gain. A comprehensive assessment has been accomplished with single‐source and dual‐source topologies, and the proposed topology shows the improved design. A low‐power laboratory porotype has been used to endorse the proposed topology with real‐time conditions.

Logistics Interoperability as a Boost Factor for Industry 4.0: Case Study of a Motorcycle Manufacturer

The Manaus Industrial Pole (PIM), located in a tax incentive area, is responsible for relevant economic growth and conservation of the Amazon Rainforest. With the advent of Industry 4.0 (I4.0) bringing new technological approaches, management, and business models and, mainly, insertion in global productive chains, it is necessary to verify the maturity and readiness of the PIM companies regarding this new environment. This article aims to verify the logistical interoperability as a boosting tool of I4.0, through applied and exploratory research, based on the case study of a motorcycle manufacturer, using a logistical interoperability measurement model based on structural equations. As a result, an overall evaluation coefficient value of 4.65 to a maximum of 5.00 was found, and the points for improvement are discussed.

GeV γ-Ray Emission of Compact Steep-spectrum Source 4C +39.23B

Abstract Thirteen yr observation data of 4FGL J0824.9+3915 with the Large Area Telescope on board the Fermi Gamma Ray Space Telescope (Fermi/LAT) are analyzed for revisiting whether 4C +39.23B, a compact steep-spectrum (CSS) source close to a flat-spectrum radio quasar (FSRQ) 4C +39.23A in the γ-ray emitting region of 4FGL J0824.9+3915, is a γ-ray emitter. We find that the time-integrated γ-ray emission of 4FGL J0824.9+3915 is overwhelmingly dominated by 4C +39.23A. It shows significant variability at a 6.7σ confidence level and the average γ-ray flux in the 0.1–300 GeV energy band is (1.60 ± 0.15) × 10−8 ph cm−2 s−1 with a power-law photon spectral index of 2.48 ± 0.05. During MJD 57500–58500, 4FGL J0824.9+3915 is in a low state with a steady γ-ray flux. Through the analysis of the Fermi/LAT observation data in this time interval, it is found that the test statistic values of the γ-ray emission from 4C +39.23A and 4C +39.23B are ∼5 and ∼31, respectively, indicating that the γ-ray emission in this time interval is dominated by CSS 4C +39.23B. The derived average flux in this time interval for 4C +39.23B is (9.40 ± 4.10) × 10−9 ph cm −2 s−1 with Γ γ = 2.45 ± 0.17. Attributing the spectral energy distribution (SED) of 4C +39.23B to the radiations from its core and extended region, we show that the SED can be represented with a two-zone leptonic model. Its γ-ray emission is contributed to by the core region. The derived magnetic field strength and Doppler boosting factor of the core are 0.13 G and 6.5. Comparing 4C +39.23B with other γ-emitting CSSs and compact symmetric objects (CSOs) in the Γ γ − L γ plane, it resembles CSSs.

Modeling and Control of Single-Stage Quadratic-Boost Split Source Inverters

This paper aims to develop the recently introduced Spilt-Source Inverter (SSI) topology to improve its boosting characteristics. New SSI topologies with high voltage gain are introduced in this paper. The proposed converters square the basic SSI’s boosting factor by utilizing an additional inductor, capacitor, and two diodes. Thus, the proposed converters are called Quadratic-Boost (or Square-Boost) SSIs (QBIs or SBIs). Four different QBI topologies are presented. One with continuous input current (CC-QBI), and the other draws a discontinuous input current (DC-QBI) but with reduced capacitor voltage stresses. This paper also introduces the small-signal model of the CC-QBI using state variables perturbance. Based on this model, the closed-loop voltage and current control approach of the dc-boosting factor are designed. Moreover, a modified space vector modulation (MSVM) scheme is presented to reduce the input current ripples. To evaluate the performance of the proposed topologies, a comparative study between them and the other counterpart from different perspectives is introduced. It can be found that the CC-QBI topology has superior boosting characteristics when operating with low input voltage compared with their counterparts. It has a higher boosting capability, lower capacitor voltages, and semiconductor stresses, especially when high voltage gains are required. These merits make the proposed topologies convenient to the Photovoltaic and Fuel-Cell systems. Finally, the feasibility of the suggested topology and the introduced mathematical model is verified via simulation and experimental results, which show good accordance with the theoretical analysis.

A Three-Level Single Stage A-Source Inverter With the Ability to Generate Active Voltage Vector During Shoot-Through State

Single-stage boosting capability of impedance network (IN) inverters makes this family of inverters an attractive choice for DC/AC applications with low input DC voltage. A specific time of shoot-through (ST) state is required to achieve the required voltage gain. Conventionally ST state and zero output voltage vector should be applied simultaneously. This constraint limits the modulation index and increases the voltage stress of the semiconductor devices, particularly for applications requiring a high boosting factor. In this paper, as the boosting stage for a three-level inverter, a new modified configuration of A-source IN with two series outputs is proposed and connected to a 10-switches three-level inverter. Besides generating two outputs by a single IN, the proposed DC/AC inverter is able to apply an active voltage vector during the ST state. This capability improves the DC/AC voltage gain, increases the modulation index, and decreases the required ST time. The operation principles are described, and the steady-state relations are derived. It is compared with other magnetically coupled INs in terms of boost factor and voltage stress of switches. Considering the 10-switches three-level inverter as the front-end inverter, an adopted maximum boost strategy using the space vector modulation is developed targeting minimum ST time. Finally, a laboratory prototype of the converter is developed, and several tests are carried out. The results validate the given theories and simulations.