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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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Beam frame representation for ultra-wide-band radiation from volume source distributions: Frequency domain and time domain formulations
摘要： We present two novel beam summation (BS) schemes for radiation from time-harmonic or time-dependent volume source distributions, where the field is expanded using a discrete phase-space set of beam-wave propagators. The generic term “beams” is used here for both the frequency-domain and the time-domain formulations where the propagators are iso-diffracting Gaussian beam (ID-GB) or iso-diffracting pulsed beams (ID-PB), respectively. The formulations are structured upon the recently formulated “beam-frame” theorem that establishes these phase-space beam-sets as frame-sets everywhere in the propagation domain, and not only over the aperture plane as in previous formulations. The expansion coefficients are obtained by projecting the source distributions over the dual beam-frame sets that have essentially the same structure as the basic sets. As such, these formulations constitute local generalization to the conventional plane-waves or Green’s function formulations, and also reduce the overall degrees of freedom needed to describe the radiated field. As demonstrated by the numerical examples they resolve the local features of the source distributions in space-time, and hence provide a basis for a new local inverse scattering theory to be presented subsequently.
关键词： beam summation methods,pulsed beams,Gaussian beams,phase space representations,ultra wide band,time domain,Radiation theory
更新于2025-09-23 15:21:21
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A Thermally Induced Perovskite Crystal Control Strategy for Efficient and Photostable Widea??Bandgap Perovskite Solar Cells
摘要： Wide-bandgap perovskite solar cells (WBG PSCs) have gained attention as promising tandem partners for silicon solar cells due to their complementary absorption, superb open-circuit voltage, and easy solution process. Recently, both their performance and stability have been improved by compositional-engineering or defect-passivation strategies, due to modulation of perovskite crystal size and reduction of crystal defects. In this work, we report a thermally induced phase control (TIPC) strategy, which enables efficient and photostable WBG PSCs without any compositional engineering by exploring a thermal annealing process window of WBG perovskite films for the annealing temperature and time range of 100-175°C and 3-60 minutes, respectively. Within this window, we found a key annealing regime that produces preferred crystal orientations of lead iodide and the WBG perovskite, suppressing phase segregation and reducing charge recombination in the perovskites. The WBG PSC (composition of FA0.75MA0.15Cs0.1PbI2Br and Eg of 1.73 eV) optimized by TIPC exhibited an excellent power conversion efficiency (PCE) of 18.60% and improved operational stability, maintaining >90% of the maximum PCE (during maximum power point tracking) without encapsulation after 12-hour operation under AM 1.5G irradiation in ambient air conditions and after 500-hour operation under white LED irradiation (100 mW cm-2) in inert N2 gas conditions.
关键词： wide-band gap perovskite,thermal annealing process,operational stability,perovskite solar cells,invariant bandgap
更新于2025-09-23 15:21:01
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[Lecture Notes in Electrical Engineering] Microelectronics, Electromagnetics and Telecommunications Volume 521 (Proceedings of the Fourth ICMEET 2018) || Wide Band Sierpinski Carpet Rectangular Microstrip Fractal Antenna Using Inset-Fed for 5G Applications
摘要： The objective of this paper is to propose a wide band Sierpinski carpet rectangular microstrip fractal antenna fed with inset-fed for 5G applications. This proposed antenna design consists of the third iteration of Sierpinski carpet fractal on the rectangular patch and partial ground structure print on both sides of FR4 epoxy material with a dielectric constant of 4.4 and 0.4 mm thickness at 28 GHz. The simulated result shows a wide impedance bandwidth of 9.16 GHz and 8.43 dB gain. It can further be con?gured to an array of fractals for high gain and bandwidth, frequency selective surface (FSS), and radar applications.
关键词： Inset-fed and partial ground,Fractal antenna,Wide band,Sierpinski carpet
更新于2025-09-23 15:21:01
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Efficiency Limits of Underwater Solar Cells
摘要： Operation of underwater vehicles and autonomous systems is currently limited by the lack of long-lasting power sources. These systems could potentially be powered using underwater solar cells, but the material requirements to achieve their full potential are not well understood. Using detailed-balance calculations, we show that underwater solar cells can exhibit efficiencies from ~55% in shallow waters to more than 65% in deep waters, while maintaining a power density >5 mW cm?2. We show that the optimum band gap of the solar cell shifts by ~0.6 eV between shallow and deep waters and plateaus at ~2.1 eV at intermediate depths, independent of geographical location. This wide range in optimum band-gap energies opens the potential for a library of wide-band-gap semiconductors to be used for high-efficiency underwater solar cells. Our results provide a roadmap for proper choice of underwater solar cell materials, given the conditions at points of use.
关键词： wide-band-gap semiconductors,detailed-balance calculations,efficiency limits,power density,underwater solar cells
更新于2025-09-23 15:19:57
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A 2.77 μW Ambient RF Energy Harvesting Using DTMOS Cross-Coupled Rectifier on 65 nm SOTB and Wide Bandwidth System Design
摘要： This paper proposes a structure of the μW RF energy harvesting (RFEH) system that is used for scavenging RF power from an ambient environment. A cross-coupled recti?er (CCR) with ?oating sub-circuit structures was utilized in the application of dynamic threshold MOSFET (DTMOS) on Silicon on Thin Buried Oxide (SOTB) to obtain high drain conductance of the MOSFET. A wide bandwidth matching between antenna and recti?er was designed to receive energy from the orthogonal frequency division multiplexing (OFDM) RF signal with a bandwidth of 15 MHz at 950 MHz band. Realistic measurements with a 950 MHz LTE mobile phone signal from the ambient environment indicate that an average DC output power of 2.77 μW is harvested with the proposed RFEH system at a level of ?19.4 dBm input power. The proposed RFEH system exhibits the best performance when compared to that of other realistic RFEH systems and is a potential candidate for battery-less Internet of Things (IoT) applications.
关键词： wide band matching circuit,DTMOS cross-coupled recti?er,ambient environment,LTE mobile phone signal,RF energy harvesting
更新于2025-09-19 17:13:59
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Dual-band substrate integrated waveguide dual-dumbbell-shaped-slot-fed patch antenna
摘要： A dual-band low-profile substrate integrated waveguide (SIW) dual-dumbbell-shaped-slot-fed (DDSSF) patch antenna is presented in this letter. The antenna is designed using the dual-dumbbell-slot feeding structure in SIW and two patches to radiate. And it achieves two passbands by exciting two modes of dual dumbbell-shaped slots (DDSSs). The first impedance bandwidth is 4.1%, the second one is 10.0% and gains up to 6.7 dBi and 7.4 dBi, respectively. Furthermore, the two bands can be separated from each other and the cross-polarization level is below ?30 dB. The simulation and measurement results of the proposed antenna are in good agreements.
关键词： slot,substrate integrated waveguide (SIW),dumbbell-shaped,dual-wide-band,low cross-polarization
更新于2025-09-19 17:13:59
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Tunnel oxide passivating electron contacts for high‐efficiency n‐type silicon solar cells with amorphous silicon passivating hole contacts
摘要： Organic photovoltaics (OPVs) consisting of a wide bandgap polymer donor and a nonfullerene acceptor (NFA) have received attention because they can effectively overcome the weaknesses of efficiency and stability for fullerene-based OPVs. One of the NFAs, ITIC, shows an excellent power conversion efficiency, as well as controllable solubility, absorption, crystallinity, and energy level. Thus, high-efficiency OPVs could be achieved by developing polymer donors appropriate for use with ITIC-based OPVs. In this study, the synthesized polymer donor, PBDTT-8ttTPD, containing alkylthieno[3,2-b]thiophene as π-bridge and thieno[3,4-c]pyrrole-4,6(5H)-dione (ttTPD) shows strong absorption with a sharp peak edge at around 700 nm. In addition, the high hole mobility and face-on oriented polymer structures in the blend films make ttTPD the best candidate for the donor in NFA-based OPVs. Notably, the molecular weight of the face-on preferred polymer donor is crucial for determining the power conversion efficiency (PCE) of the NFA-based devices. A high molecular weight improves the π?π stacking ordering, absorption, and nanomorphology of the blend films, resulting in a dramatic PCE improvement from 5.76% to 11.05% compared with that of the fullerene-based OPV device (7.86%).
关键词： organic photovoltaics,nonfullerene acceptors,molecular weight,TPD-based polymer,wide band gap donnor polymer
更新于2025-09-19 17:13:59
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[IEEE 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - Rome, Italy (2019.6.17-2019.6.20)] 2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) - A Singular Value Decomposition Based Approach for Classifying Concealed Objects in Short Range Polarimetric Radar Imaging
摘要： In current research one of the main challenges in short range synthetic aperture radar (SAR) is electrically small structures and objects, which tend to unclear reinforced or through the wall objects, object orientation angle, and obscure contribution to extract the position of concealed multiple small objects. In this paper, ultra-wide-band (UWB) polarimetric radar was used to study reinforced objects and for estimation of object angle at short range. Electrically small 1D periodic mesh, 2D periodic meshes and di?erently oriented small objects or meshes could not be distinguished in conventional SAR images. A radar system with transmit and receive antennae mounted on a two dimensional scanning grid was used. The aim is non-destructive testing of built structures, in concrete slab manufacturing and for use in the renovation process. UWB short range radar data and images corresponding to di?erent polarization states were analysed by using singular value decomposition (SVD). To perform decomposition, the proposed approach applies SVD to image data matrices produced from the back projection algorithm (BPA) to classify the di?erent objects and identify the object angle. Then, sets of singular-components of di?erent polarization states are analysed to classify objects. Also, the BPA algorithm is performed to construct the object images from the polarimetric radar signals. The object re?ection varied with the polarimetric state of the UWB radar, which contributes to di?erent object signatures (i.e., object intensity) since the object signature depends on the orientation, the size, and the number of objects. Object orientation with respect to the radar system and object anisotropy could be determined from the ratio of the di?erent polarimetric singular-components. This proposed complex data analysis method demonstrates the usefulness of the SVD using BPA in extracting more information about and for classifying an object.
关键词： back projection algorithm (BPA),object classification,ultra-wide-band (UWB) polarimetric radar,Synthetic aperture radar (SAR),singular value decomposition (SVD)
更新于2025-09-19 17:13:59
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Light controlled (super) cascode, LC(S)C, a power device with optical turn-on and -off
摘要： The proposed light-controlled cascode is a power electronic device (or circuitry) which can be turned-on and -o? by optical excitation. In contrast to the light-triggered thyristor, which can optically be turned-on but not -o?, the proposed device allows optical turn-on and -o?. Also, it allows a scalability of the blocking voltage by the extension to a light-controlled supercascode [1] which is also shown. After a brief theoretical consideration experimental set-ups will be presented and measurements are shown. Due to the di?culty to buy appropriate devices required for the experimental set-ups some compromises were necessary. Therefore, these ?rst experiments show a very slow switching behaviour. However, this could become speeded up by an optimized photodiode made from wide band gap semiconductor material. In spite of these compromises pulses with a power of 1 kW were turned-on and – o? by the experimental set-up. However, this device is far away from being ready for series production but the feasibility is demonstrated and the potentials are shown.
关键词： optical isolation,wide band gap,supercascode
更新于2025-09-19 17:13:59