271 research outputs found
Bidirectional Flyback Converter for Dielectric Electro Active Polymer: Harvesting energy via a novel Dielectric Electro Active Polymer Generator
No full textIn this student project the efforts during thefall and spring semester 2013-2014, whichcorresponds to 9th and 10th semester of theeducation, have been introduced.The project deals with design of a bidirectionalflyback converter for DielectricElectro Active Polymer Generator (DEAP).Firstly an introduction to the energy harvestingcycles has been made. Afterwards, theconverter is discussed theoretically and in orderto enhance the efficiency of the convertertwo SiC MOSFET employed to work in series.Therefore, a brief discussion on series connectiontechniques are done and gate balancingcore technique was utilized to provide balancedvoltage distribution at switching transients.Finally the converter has been built atlaboratory of AAU and experiments have beenperformed which are different voltage levels
Peak oxygen uptake correlates with disease severity and predicts outcome in adult patients with Ebstein's anomaly of the tricuspid valve
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Power Electronics Converter for Polymer Capacitor Generator
No full textThis Master thesis deals with the analysis, simulation and step-by-step design, implementation and experimental testing processes of a tapped inductor power electronics converter, associated with the energy harvesting process of a Dielectic ElectroActive Polymer (DEAP) generator. In order to enhance the operational voltage range of the converter, while sustaining a high degree of energy efficiency, the ‘gate balancing core’ technique has been employed to serialize a number of switches. Numerous experiments on the serialization of switches as well on the converter operation are conducted in the laboratoy of AAU and in this thesis they are presented and discussed
Detrimental impact of socioeconomic status on exercise capacity in adults with congenital heart disease
No full textCorrigendum to “Delta SARS-CoV-2 variant is entirely substituted by the omicron variant during the fifth COVID-19 wave in Attica region” [Sci. Total Environ., 856(Pt 1) (2023)/159062] (Science of the Total Environment (2023) 856(P1), (S0048969722061617), (10.1016/j.scitotenv.2022.159062))
No full textThe authors state that the printed version of the above article missed the contribution of an author, which was that the third author had contributed to the writing of the original draft in addition to methodology. The correct and final version follows. CRediT authorship contribution statement Aikaterini Galani: Methodology, Validation, Writing – original draft. Athina Markou: Supervision, Writing – review & editing, Project administration. Lampros Dimitrakopoulos: Methodology, Writing – original draft. Aikaterini Kontou: Validation. Marios Kostakis: Validation. Vasileios Kapes: Methodology. Marios A. Diamantopoulos: Formal analysis, Software. Panagiotis G. Adamopoulos: Formal analysis. Margaritis Avgeris: Formal analysis, Writing– review & editing. Evi Lianidou: Writing – review & editing. Andreas Scorilas: Formal analysis. Dimitrios Paraskevis: Writing – review & editing. Sotirios Tsiodras: Writing – review & editing. Meletios-Athanasios Dimopoulos: Funding acquisition, Writing – review & editing. Nikolaos Thomaidis: Conceptualization, Project administration, Visualization, Resources. © 2022 Elsevier B.V
An RCDD snubber for a bidirectional flyback converter
No full textIncreased usage of renewable energy sources has boosted the demand for power electronics converters. Indeed, the DC/DC flyback converter is nowadays frequently used in applications where isolation is required, due to its low component count, simple structure and high energy efficiency. One of the major challenges faced in a flyback converter is the excess voltage stress sensed by its semiconductor devices, because of the interrupted current flow through its transformer leakage inductances. In this paper, a high-efficient bidirectional flyback converter, operating in discontinuous conduction mode, is examined with an integrated RCDD snubber. Additionally, experimental comparison where the converter runs with a typical RCD and RCDD snubber network, is done. Experimental results on an IGBT-based bidirectional flyback converter validate the applicability of the RCDD snubber demonstrating energy efficiency above 90%. Furthermore, the operation of the bidirectional converter with the employed snubber is thoroughly analysed and an appropriate mathematical analysis is conducted highlighting all the design specifications of the proposed snubber.</p
Energy Harvesting Cycles of Dielectric ElectroActive Polymer Generators
No full textEnergy harvesting via Dielectric ElectroActive Polymer (DEAP) generators has attracted much of the scientific interest over the past few years, mainly due to the advantages that these smart materials offer against competing technologies, as electromagnetic generators and piezoelectrics. Their higher energy density, superior low-speed performance, light-weighted nature as well as their shapely structure have rendered DEAPs candidate solutions for various actuation and energy harvesting applications. In this paper, a thoroughly analysis of all energy harvesting operational cycles of a DEAP generator, coupled to a non-isolated power electronics converter, is conducted and for the first time experimental results for each one of them are presented
A Tapped-Inductor Buck-Boost Converter for a Dielectric ElectroActive Polymer Generator
No full textEnergy harvesting applications based on Dielectric ElectroActive Polymer (DEAP) generators have been in the spotlight in recent years after the latter ones’ documented advantages against competing electromagnetic and field-activated technologies. Yet, the need for bidirectional energy flow under high step-up and high step-down voltage conversion ratios, accompanied by low-average but relatively high-peak currents, imposes great challenges on the design of the employed power electronic converter. In addition, the effective operational range of the converter is usually limited by the lack of commercially-available, high-efficient, high-voltage, low-power semiconductor devices. In this paper, a high-efficient bidirectional tapped-inductor buck-boost converter, addressing high step-up and high step-down voltage conversion ratios, is proposed for energy harvesting applications based on DEAP generators. The high-side switch of the converter is replaced by a string of three non-matched, non-thermally-coupled, off-the-shelf MOSFETs, extending its effective operational range. Experiments conducted on a standalone DEAP generator validate the applicability of the proposed converter by demonstrating energy harvesting of 0.42 J, at 0.75 Hz and 60 % delta-strain, characterized by a world-first; energy density equal to 2 J per kg of active material
Serializing off-the-shelf MOSFETs by Magnetically Coupling Their Gate Electrodes
No full textWhile the semiconductor industry struggles with the inherent trade-offs of solid-state devices, serialization of power switches, like the Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) or the Insulated Gate Bipolar Transistor (IGBT), has been proven to be an advantageous alternative to acquire a high-efficient, high-voltage, fast-switching device. More than twenty years of research, on the serialization of solid-state devices, have resulted into several different stacking concepts. Among the prevailing ones, the gate balancing core technique, which has demonstrated very good performance in strings of high-power IGBT modules. In this paper, the limitations of the gate balancing core technique, when employed to serialize low or medium power off-the-shelf switches, are identified via experimental results. A new design specification for the interwinding capacitance of the employed transformer is derived to address those limitations, leading to a revised version of the technique. The effectiveness and the applicability of the revised gate balancing core technique are verified, via experiments conducted on a string of two off-the-shelf, non-matched MOSFETs, installed in an inductively loaded step-down converter
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