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[IEEE 2020 11th Power Electronics, Drive Systems, and Technologies Conference (PEDSTC) - Tehran, Iran (2020.2.4-2020.2.6)] 2020 11th Power Electronics, Drive Systems, and Technologies Conference (PEDSTC) - Utilization of Soft-Switched Boost Converter for MPPT Application in Photovoltaic Single-Phase Grid-Connected Inverter
摘要： A modified soft-switched boost converter with a lower number of auxiliary components is proposed in this paper that provides either zero-voltage-transition (ZVT) or zero-current-transition (ZCT) operation for main switch and diode. Proposed converter is utilized in a single-phase grid-tied photovoltaic power generation system. Due to importance of maximum power harvesting from PV, incremental conductance MPPT procedure is employed to control DC/DC converter. Simulation is performed in PLECS software to validate the advantageous introduced soft-switching technique.
关键词： Zero-Voltage-Transition (ZVT),Zero-Current-Transition (ZCT),Single-Phase Grid-Connected Inverter,Incremental Conductance MPPT,Soft Switching Boost Converter
更新于2025-09-23 15:21:01
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The Critical Role of AlInP Window Design in IIIa??V Rear-Emitter Solar Cells
摘要： Doppler velocity can be derived by calculating Doppler shift anomalies between predicted and estimated Doppler centroids. The predicted Doppler centroid is calculated based on a geometric model of satellite assuming that the target is not moving. The estimated Doppler centroid can be directly extracted from the raw SAR signal data by applying the average cross-correlation coefficient method. It is known that wind-generated ocean waves can significantly contribute to Doppler velocity due to the correlation between orbital motions of the waves and (tilt and hydrodynamic) modulated radar cross sections, in addition to what sea surface current contributes. In this study, the characteristics of Doppler velocities under hurricane conditions were investigated using RADARSAT-1 ScanSAR raw data. Five different hurricanes (Hurricane Dean, Hurricane Ivan, Hurricane Kyle, Hurricane Lili, and Typhoon Xangsane) and sequential acquisitions of two hurricanes (Hurricane Kyle and Hurricane Lili) were selected to study the contribution of wind-induced waves to Doppler velocities and compared with in situ measurements of drifting buoys. The results show that hurricane-generated seas and associated winds and waves appear to be different from ordinary sea state. This leads to lower estimates of Doppler velocities than expected and much closer to sea surface current velocities.
关键词： RADARSAT,Doppler velocity,hurricane,drift current,wind-induced waves
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Evaluation of Unauthorization at the Express-Control of Heating of Natural Gas
摘要： Light emitting devices based on Si quantum dots/SiO2 multilayers with dot size of 2.5 nm have been prepared. Bright white light emission is achieved under the dc driving conditions and the turn-on voltage of the device is as low as 5 V. The frequency-dependent electroluminescence intensity was observed under ac conditions of square and sinusoidal wave. It was found that the emission wavelength changes with frequency when sinusoidal ac is applied. The degradation of emission intensity is less than 12% after 3 h for ac driving condition, exhibiting the better device stability compared to the dc driving one.
关键词： electroluminescence (EL),Direct current (dc),Si quantum dots (Si QDs),frequency dependent
更新于2025-09-23 15:21:01
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Alkali Metal Ions: A Secret Ingredient for Metal Nanocluster-Sensitized Solar Cells
摘要： The presence of alkali metal ions (AMIs) during the adsorption of thiolated Au nanoclusters (NCs) onto TiO2 plays a critical role in achieving high power conversion efficiency and suppressing anomalous current?voltage hysteresis in metal nanocluster-sensitized solar cells. This hidden role of the AMIs is intimately related to the adsorption strength between the NCs and TiO2, indicating the importance of seeking a comprehensive understanding of NC?TiO2 interfaces and devising interfacial engineering techniques to support the next advance in light energy conversion applications of NCs.
关键词： alkali metal ions,metal nanoclusters,current?voltage hysteresis,power conversion efficiency,solar cells
更新于2025-09-23 15:21:01
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A Novel Inverse Analysis Method to Identify Concentration and Current Density Distributions on Electrode Surface
摘要： A novel method to identify accurate polarization characteristics for a concentration-dependent electrochemical reaction was developed. This method identifies polarization characteristics which are dependent on concentration on electrode surface of a flow cell. Since the concentration on the electrode surface sitting in a flow cell cannot be measured directly, inverse analysis approach is applied. As the observation information of this inverse problem, total currents on the electrode are measured with different bulk concentration. The unknown polarization characteristics are expressed with piecewise linear function with unknown parameters. The relationship between observation and unknown parameters are modeled with advection-diffusion equation. The fluid velocity field of the flow cell is modeled with Navier-Stokes equation. These equations are discretized by finite volume method. In order to validate the proposed method, identification using both numerically generated data and experimental data were performed. The validation result demonstrated the good accuracy of the method.
关键词： inverse analysis,concentration distribution,electrochemical flow cell,current density distribution,polarization characteristics
更新于2025-09-23 15:21:01
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Power Quality Improvement Utilizing PV Fed Unified Power Quality Conditioner Based on UV-PI and PR-R Controller
摘要： This paper presents control and configuration of photovoltaic fed unified power quality conditioner for the purpose of power quality enhancement. Literature studies convey that fixed PI gains used in the control schemes of Unified Power Quality Conditioners (UPQC) and PV-UPQC cannot easily adapt to various dynamic conditions. In this paper a novel online tunings method for PI control gains is adopted in the controllers of series and shunt converters of PV-UPQC. Unlike the previously implemented JAYA algorithm which has a single objective function utilized in the controller of DSTATCOM for improvement of only current quality, the new adaptive JAYA algorithm has two separate objective function, employed in shunt and series inverter control of PV-UPQC system for improvement of both current and voltage quality under various operational scenarios for power quality issues. The experimental results verify that implementation of JAYA based auto tuning PI controller increases the adaptivity of PV-UPQC system towards various dynamic conditions. Results obtained are compared with conventional optimization algorithms with fixed PI gains pertaining to a distribution system for validating its efficacy.
关键词： current harmonics,power quality,voltage sags/swells,PV-UPQC,Adaptive JAYA Optimization
更新于2025-09-23 15:21:01
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Mechanism of leakage current increase in p-GaN gate AlGaN/GaN power devices induced by ON-state gate bias
摘要： An increase in OFF-state leakage current in p-GaN gate AlGaN/GaN high-electron-mobility transistors (HEMTs), induced by ON-state gate bias, was observed and reported in this paper. Higher OFF-state leakage current was observed with higher gate bias voltage and longer bias duration. We propose that the initial increase in OFF-state leakage current and its subsequent decay with time are due to persistent photoconductivity effects in GaN induced by hole injection and electroluminescence during the ON-state gate bias. At room temperature, it took more than 20 s for the increased leakage current to reduce to its equilibrium level in the dark. The related physical mechanisms underlying this phenomenon in the p-GaN gate HEMT structure are also proposed.
关键词： p-GaN gate,AlGaN/GaN HEMTs,persistent photoconductivity,leakage current,electroluminescence
更新于2025-09-23 15:21:01
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Optimization of optical current sensor based on rare-earth magneto-optical glass
摘要： Compared to the present diamagnetic glass used in the sensing element of optical current sensors (OCSs), the high-sensitivity characteristics of the rare-earth magneto-optical glass (REMOG) can significantly improve the performance of an REMOG sensing element. The optimization objective of this study was to enhance the sensitivity of the sensing element and reduce linear birefringence. Theoretical analysis and experimental data were combined to study the practical influences of a few factors, such as the size and spatial position of the glass, the wavelength of the incident light, and the rare-earth doping concentration, on the sensitivity of an OCS sensing element. Finally, an optimal parameter combination was obtained. The experimental results showed that the response sensitivity of the REMOG sensing element is seven times the sensitivity using diamagnetic glass.
关键词： sensitivity,paramagnetic material,optical current transformer
更新于2025-09-23 15:21:01
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Online Degradation Detection/Prediction Method for Current Transfer Ratio of Photo-Coupler Installed in Digitally-Controlled Switching Mode Power Supply
摘要： The software-implemented degradation detection/prediction of the current transfer ratio (CTR) of a photo-coupler installed in a digitally-controlled switching mode power supply was studied. The photo-coupler is one of the key devices in an isolated power supply circuit, which transmits a voltage/current signal to a controller though the isolation gap. If the CTR of the photo-coupler degrades to halfway between the normal value and the threshold of the hardware protection circuit, overvoltage/current may be supplied continuously to the load circuit and possibly cause a severe failure. By comparing the theoretical pulse width modulation (PWM) duty, which is calculated from the input/output voltage and the pre-measured power supply circuit e?ciency, and the applied PWM duty, which is calculated via feedback control, CTR degradation is detectable online. In this paper, we describe the concept of this method and verify it using both simulation and prototyping circuits.
关键词： digitally-controlled power supply,current transfer ratio,failure prediction,degradation,photo-coupler,CTR
更新于2025-09-23 15:21:01
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From Bulk to Nano: A comparative investigation of Structural, Ferroelectric and Magnetic properties of Sm and Ti co-doped BiFeO3 multiferroics
摘要： In this investigation, multiferroic bulk ceramic materials with nominal compositions Bi1-xSmxFe1-yTiyO3 (x, y=0.00, 0.03, 0.06) are synthesized by conventional solid-state reaction technique. Their corresponding nanoparticles are fabricated from these bulk powder materials using cost-effective ultrasonication method. Then, the structural and multiferroic properties of the synthesized nanoparticles and their bulk-counterparts are compared. The X-ray diffraction patterns of 6% Sm-Ti co-substituted BiFeO3 nanoparticles as well as their bulk powder materials confirm rhombohedral to orthorhombic structural phase transition. Dynamic Light Scattering analysis (DLS) demonstrates the formation of particles with a size in the range of 10-100 nm for the 6% Sm-Ti co-substituted BiFeO3 sample. The fabricated nanoparticles of this particular composition also exhibit suppressed leakage current density and enhanced ferroelectric behavior. These nanoparticles also demonstrate improved ferromagnetic behavior compared to their bulk counterparts. Thus, the present investigation illustrates the impact of Sm and Ti as co-doping elements with 6% concentration in BiFeO3 nanoparticles with improved structural and multiferroic properties required for practical applications.
关键词： nanoparticles,DLS analysis,leakage current density,multiferroic properties,ultrasonication
更新于2025-09-23 15:21:01