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[IEEE 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Design and Optimization of a Solar Power Conversion System for Space Applications
摘要： This manuscript details a design method for a 500kW solar power based microgrid system for space applications. The design method utilizes multi-objective optimization with the Genetic Algorithm considering four parameters that characterize solar power based microgrids (battery voltage, PV maximum power, PV maximum power point voltage, and number of panels per string). The final optimization metric is the ratio of daily average deliverable power to total system mass (W/kg) metric. The microgrid system is composed of a number of modular DC-DC micro-converters, of which four topologies (buck, boost, buck-boost and non-inverting buck-boost) are evaluated and compared. The non-inverting buck-boost converter is determined to be the best candidate, and the optimal system characteristics are provided and analyzed. The final system design achieves a specific power of 35.56W/kg, with optimized result of 743.7V battery voltage, 439.5W PV maximum power, 182.7V PV maximum voltage, and three panels per string. Based on the optimizations results, a prototype is designed, tested, and analyzed in terms of efficiency and low temperature reliability. The converter achieved a peak efficiency of 98.4%, a power density of 3.54W/cm3, a specific power of 3.76W/g, and operated for over 267 hours of 11-minute low temperature cycles from 0oC to -140oC.
关键词： wide band gap semiconductors,microgrids,non-inverting buck-boost,maximum power point trackers,space exploration,photovoltaic systems,design optimization,DC-DC power converters,system-level design,low temperature testing
更新于2025-09-23 15:23:52
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Regional Manufacturing Cost Structures and Supply Chain Considerations for SiC Power Electronics in Medium Voltage Motor Drives
摘要： With the growth in wide bandgap (WBG) semiconductors, specifically Silicon Carbide (SiC), the technology has matured enough to highlight a need to understand the drivers of manufacturing cost, regional manufacturing costs, and plant location decisions. Further, ongoing research and investment, necessitates analytical analysis to help inform development of wide bandgap technologies. The paper explores the anticipated device, module, and motor drive cost at volume manufacturing. It additionally outlines the current regional contributors to the supply chain and proposes how the base models can be used to evaluate the cost reduction potential of proposed research advances.
关键词： Wide bandgap,Supply chain,SiC,Wide-band gap,Wideband gap,Techno-economic,WBG,bottoms-up,Medium voltage,Motor drive,Wide band-gap,Analysis,Power electronics,Cost model
更新于2025-09-23 15:22:29
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Highly-transparent, UV-B protective Al-Zn-O films with potential application in greenhouse screen systems
摘要： Extremely thin, Al-Zn-O composite films (21±6 nm) are deposited on fused silica substrates under various percentages of oxygen in the oxygen/argon gas mixture (3, 4.5, 6, and 7.5 %). The films are prepared by a cylindrical DC magnetron sputtering system, utilizing a single compound target. The effects of the oxygen percentage on the compositional, morphological, and optical properties of the films are investigated by energy-dispersive X-ray spectroscopy, scanning electron microscopy, UV-Visible spectrophotometry, and atomic force microscopy. The chemical composition of the films is Al1 Z1+X O with 0.2<X<1. The average visible transmittance of 93.6% with a high level of uniformity is obtained when the sputtering deposition performs under the oxygen percentage of 6%. It is found that the optical band gap of the films can be tailored towards higher energy by increasing oxygen percentage; however, the adjustable range is not so significant. The results offer cost-efficient films with high, uniform transmittance in the visible region and with an ability to attenuate more than 10% of incident UV-B radiation (280-315 nm). This type of films can potentially be included in greenhouse screen systems to effectively protect the plants from the elevated UV-B radiation without altering natural conditions.
关键词： Al-Zn-O film,cylindrical DC magnetron sputtering,band gap tailoring,effective UV-B protection of plants
更新于2025-09-23 15:22:29
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First-principles study of the surface reparation of ultrathin InSe with Se-atom vacancies by thiol chemistry
摘要： Utilizing first-principles calculations, the surface reparation of monolayer InSe with Se-atom vacancies by thiol chemistry was studied. The geometrical structures and electronic properties of monolayer InSe with Se-atom vacancies were evaluated before and after reparation by S atoms, benchmarked against defect-free case. The parameters of bond lengths, band gaps and carrier mobilities can be recovered to the standard of pristinely defect-free structure. Moreover, the interaction of S atom with complete part of monolayer InSe was also investigated. S atom cannot adsorb on the surface without Se-atom vacancies, while it can substitute Se atom or insert into the interior of monolayer InSe. And the insertion was able to induce a decrease by one order of magnitude. It was demonstrated that thiol chemistry was an effective method to repair Se-atom vacancies and maintain its oxidation resistance, while the insertion of S atom into the interior of monolayer InSe should be avoided.
关键词： Indium selenides,Carrier mobility,Se-atom vacancies,Band gap,First-principles
更新于2025-09-23 15:22:29
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Modification of graphene oxide with titanium dioxide by alcoholic reduction
摘要： Graphene oxide (GO) nanocomposites doped with DEGUSSA (P25) was synthetized by (GO) alcoholic reduction at high temperatures, during the reduction the P25 anchored to the spaces left by carbonyls groups in the graphene network, this incorporation improved photocatalytic behavior by retarding the electro-hole pair (e? hC). Raman spectroscopy con?rms the anchorage, because the material with higher load of TiO2 presented a band at 1100 cm?1 belonging to Carbonate’s groups (CO3) and a total modi?cation of the bands D and G, also this material presents a band gap of 2.54 eV. The P25 incorporation into graphene three-dimensional arrangement is notorious in diffraction x ray patterns, because the graphene diffraction pattern shows a sharpened and smaller peak than the starting graphene oxide. The incorporation of TiO2 to graphene sheets, improved the band gap, which P25 being of 3.2 eV was reduced to almost 2.5 eV, naturally this allows it, to be an excellent material to be used as photoanodes, photovoltaic devices and photocatalysis, its demonstrated by a photodegradation of methylene blue at 60 ppm exposed to solar light and 25 ppm exposed to a sodium lamp that emits radiation close to 589 nm.
关键词： methylene blue degradation,Band gap,graphene oxide,titanium dioxide
更新于2025-09-23 15:22:29
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Design and Optimization of a Solar Power Conversion System for Space Applications
摘要： This manuscript details a design method for a 500kW solar power based microgrid system for space applications. The design method utilizes multi-objective optimization with the Genetic Algorithm considering four parameters that characterize solar power based microgrids (battery voltage, PV maximum power, PV maximum power point voltage, and number of panels per string). The final optimization metric is the ratio of daily average deliverable power to total system mass (W/kg) metric. The microgrid system is composed of a number of modular DC-DC micro-converters, of which four topologies (buck, boost, buck-boost and non-inverting buck-boost) are evaluated and compared. The non-inverting buck-boost converter is determined to be the best candidate, and the optimal system characteristics are provided and analyzed. The final system design achieves a specific power of 35.56W/kg, with optimized result of 743.7V battery voltage, 439.5W PV maximum power, 182.7V PV maximum voltage, and three panels per string. Based on the optimizations results, a prototype is designed, tested, and analyzed in terms of efficiency and low temperature reliability. The converter achieved a peak efficiency of 98.4%, a power density of 3.54W/cm3, a specific power of 3.76W/g, and operated for over 267 hours of 11-minute low temperature cycles from 0oC to -140oC.
关键词： low temperature testing,photovoltaic systems,wide band gap semiconductors,maximum power point trackers,design optimization,non-inverting buck-boost,space exploration,system-level design,DC-DC power converters,microgrids
更新于2025-09-23 15:22:29
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Optical Characteristics of Zinc Oxide Films on Glass Substrates
摘要： An algorithm is developed for solving the inverse problem of multiangular spectrophotometry of a layer on a plane-parallel substrate of finite thickness using s- and p-polarized waves. It allows the dispersive properties of the layer and substrate to be studied both far from and in the vicinity of the resonant wavelengths. The dispersive properties of layers of pure and Al-doped ZnO on glass substrates are investigated using it. It is shown that doping shifts the absorption band maximum to shorter wavelength and decreases the refractive index of the material. The applicability limits of known approximate expressions for determining the spectral dependence of the absorption coefficient of a layer from spectrophotometric data are estimated.
关键词： band gap,refractive index and absorption coefficient,multiangular spectrophotometry,ZnO
更新于2025-09-23 15:22:29
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Stability, Electronic and Magnetic Properties of Rare Earth (Eu, Tm) Implanted InGaN
摘要： The electronic structure and magnetic behavior of InGaN:RE (RE = Eu, Tm) have been studied by using scalar relativistic full-potential linear augmented-plane-wave plus local orbital (FPLAPW + lo) calculations with LSDA+U approximation. Band structure and density of states are analyzed. It appears that the In-site is the preferred site for doping InGaN alloy with rares earth (Eu, Tm) from the formation energy. Our study reveals that these materials are semiconductors with a direct band gap of 1.2345 eV and 1.3657 eV for InGaN:Eu and InGaN:Tm respectively. The total energy of the FM phase is lower than the AFM total energy; this confirms the fact that the ground state at zero temperature is ferromagnetic. A small-induced magnetic moment on other nonmagnetic atoms (Ga, In, and N) and the total magnetic moment of these compounds is mainly due to RE-4f states.
关键词： InGaN alloy,Europium,DMS,Direct band gap,Thulium
更新于2025-09-23 15:22:29
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Optical Band Gap, Local Work Function and Field Emission Properties of MBE Grown β-MoO3 Nanoribbons
摘要： Monoclinic molybdenum trioxide (β-MoO3) nanostructures (shaped like nanoribbons: NRs) were grown on Si(100), Si(5512) and fluorine-doped tin oxide (FTO) by molecular beam epitaxy (MBE) technique under ultra-high vacuum (UHV) conditions. The dependence of substrate conditions and the effective thickness of MoO3 films on the morphology of nanostructures and their structural aspects were reported. The electron microscopy measurements show that the length and the aspect ratio of nanostructures increased by, 260% without any significant change in the width for a change in effective thickness from 5 nm to 30 nm. NRs are grown along <011> for all the effective thickness of MoO3 films. Similarly, when we increased the film thickness from 5 nm to 30 nm, the optical band gap decreased from 3.38± 0.01eV to 3.17± 0.01eV and the local work function increased from 5.397 ± 0.025 eV to 5.757 ± 0.030 eV. Field emission turn-on field decreased from 3.58 V/μm for 10-μA/cm2 to 2.5 V/μm and field enhancement factor increased from 1.1×104 to 5.9×104 for effective thickness variation of 5 nm to 30 nm β-MoO3 structures. The β-MoO3 nanostructures found to be much better than the α-MoO3 nanostructures due to low work function, low turn on field and high field enhancement factor, and are expected to be useful applications.
关键词： β-MoO3 nanostructures,Field emission and Kelvin probe force microscopy (KPFM),Optical band gap,Molecular beam epitaxy (MBE),Electron microscopy
更新于2025-09-23 15:22:29
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Effect of Ni substitution on the structural and optical properties of SrZr1-xNixO3 (0.05≤x≤0.20) perovskites
摘要： Ni2+ substituted SrZr1-xNixO3 (x = 0.05, 0.10, 0.15, 0.20) perovskites are synthesized by the solid-state reaction method. Their structural, morphological and optical properties are characterized using X-ray diffraction (XRD), scanning electron microscopy with attached energy dispersive spectroscopy (SEM-EDS), UV-Visible (UV-Vis) and photoluminescence spectroscopy (PL). The XRD patterns of all the samples show the formation of a single phase, i.e. orthorhombic phase, which is further confirmed by Rietveld refinement. Structural ordering increases with an increase in the concentration of Ni2+ substitution with an increase in the mean crystallite size. The optical band gap of all the samples is in the insulating range, i.e., around 5 eV. The intensity of the PL spectra decreases with substitution concentration due to the quenching effect.
关键词： Rietveld refinement,Photoluminescence,Band gap,Perovskite structure
更新于2025-09-23 15:22:29