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This paper presents a method for assess the risk index in a power transformers park, risk index is a metric that allows park administrator to ensure an optimal physical asset management, allocating properly financial and human resources in operation and maintenance actions. Assessing risk index requires calculating two secondary sub-index termed failure probability and consequence factor. Those indexes...
In these years, the wind power integration capacity has increased a lot, and the issue of wind curtailment has become more serious for lack of adequate flexible energy sources. To find out whether the nuclear power plant (NPP) in the present power system can solve this issue, this paper proposes a joint operational optimization model that includes the NPP, wind power plant, thermal units and pumped-storage...
In this paper, we consider the design problem of a decentralized variable gain robust controller that provides practical tracking for a class of large-scale interconnected systems with mismatched uncertainties. Furthermore, we show that sufficient conditions for the existence of the proposed decentralized variable gain robust controller are reduced to the feasibility of linear matrix inequalities...
Wide-bandgap (WBG) power devices such as SiC devices can operate at higher switching speed, higher voltage and higher temperature. While the opportunities in performance improvement with WBG devices are clear, there are significant design challenges. For example, the fast switching speed and high dv/dt can cause increased level of electro-magnetic interference (EMI), current overshoot and cross-talk...
In this work, a comparative study for the n-type emitter formation in the fabrication of simple structures of crystalline silicon (c-Si) solar cells is reported. Gas and spin on dopant sources were employed in the pn junction formation of the solar cells in order to compare their performance. Phosphine (PH3) was used as n-type gas for phosphorus diffusion while the Filmtronics Spin-On Dopant SOD-P905...
The influence of light illumination on the programming of a capacitor floating gate memory based on Ge nanocrystals in HfO2 was studied. The capacitor was fabricated on a c-Si substrate by magnetron sputtering deposition of a layer sequence of HfO2/Ge-HfO2/HfO2 and post-growth rapid thermal annealing for nanocrystals formation at 600 oC. The illumination of the structure was performed through a semi-transparent...
Gallium Nitride (GaN) based power devices have been demonstrated to deliver higher energy efficiency than their Silicon (Si) counterparts for 200–1.2kV rated applications. The benefits of GaN technologies and their market potential will be highlighted in this paper together with the main challenges that GaN-based power systems need to overcome to reach their full potential and finally enter the market...
In this paper, the basic principles of Near-Field Microscopy will be reviewed with focus on the micro- and nano-scale resolution configurations for material science measurements. Results on doping profile, dielectric and magnetic properties will be presented, with details on the calibration protocols needed for quantitative estimation of the dielectric constant and of the permeability.
Recent advances and new trends in high voltage SiC based MOSFETs are analyzed. The main focus is done on design optimization strategies for reducing the on-state resistance. Gate oxide treatments for improving the interface quality resulting in a lower channel resistance are reviewed as well as solutions for lowering the JFET and bulk resistance components. The 3rd quadrant operation, short-circuit...
Morphing is a technique that smoothly transforms a shape onto another. In this paper, we present a method for morphing of two dynamic meshes: mesh sequences representing the keyframes of animated shapes over time. The pipeline of the proposed method comprises two main stages: template-based cross-parameterization and dynamic mesh interpolation. In the cross-parameterization stage, we use a variation...
The electrical and photosensing properties correlated with structure and morphology of TiO2/(GeSi/TiO2)2 multilayers are investigated. The multilayers are prepared by magnetron sputtering followed by rapid thermal annealing. Studies of Raman spectroscopy, transmission electron microscopy and X-ray diffraction are carried out. Measurements of dark current versus voltage and temperature are done. The...
Although the hybrid switch consisting of high power Si IGBT and low power SiC MOSFET achieves reduction of losses and cost, there is a severe concern of its short-circuit capability due to its internal SiC MOSFET with small die size. Experimental study shows that the short-circuit capability of hybrid switch is limited by that of SiC MOSFET. The physical mechanism of short-circuit capability of SiC...
Bi-directional switches, also called four quadrant switches (FQS), are the basic building blocks in many power converter circuits, such as cyclo-converters, matrix converters etc. Conventional approaches to realize bi-directional switch involves combination of unidirectional controllable blocking device (IGBT or MOSFET) and diode. In this approach, current flows through multiple devices for any direction...
Gallium nitride (GaN) devices, as their better performance in high temperature, high efficiency and high power density converters, have been recognized as the most promising successor for Si MOSFET in the future. In order to take advantages of the superiority of depletion-mode GaN devices, a low voltage Si MOSFET is in series to drive the depletion-mode GaN device, which is well known as cascode structure...
This paper presents a high efficiency SiC power converter in pulsed power applications. SiC Power MOSFETs have 7∼10 times lower switching loss than Silicon counterparts. However, because of the large depletion capacitance, the SiC device switching loss will be higher than silicon device at zero current. Therefore, loss reduction method is proposed to further improve SiC gradient driver efficiency...
This paper is focused on the dynamic modelling of the polycrystalline silicon wafer-based photovoltaic cells under various operational and fault conditions. The models are drawn from the impedance changes observed using electrochemical impedance spectroscopy. In this paper, tests were carried out at different voltage bias levels under illumination, dark, uniform partial shading, and cell-mismatch...
With their intrinsic superiorities such as high breakdown electric field and high thermal conductivity, SiC MOSFETs are replacing Si IGBTs in power electronics applications. However, at higher voltages SiC MOSFETs are at early stage of development and are not commercialized yet. For the first time, this paper presents thorough static and dynamic performance characterization of 3.3 kV and 30 A discrete...
In this paper, a comparative evaluation between a commercial 3.3 kV/400 A Si-IGBT and a 3.3 kV/400 A SiC MOSFET power module in half-bridge configuration is presented. With a constant current of 250 A, a lower forward voltage (VDS) drop of 1.6 V is obtained for SiC MOSFET at 300 K compared to Si IGBT. At 400 A, the difference is reduced to 1.3 V. SiC MOSFET offers an on-state resistance of 8.7 mΩ,...
In this paper, a resonant switched-capacitor dc-dc converter is proposed for data center application. The proposed converter possesses features such as high efficiency, high power density and light-weight. Zero current switching (ZCS) can be achieved with the resonant operation, which allows the converter operating under high efficiency. Proper switching device selection and in-depth power loss analysis...
High-density packaging of fast-switching power semiconductors typically requires low thermal resistance and parasitic inductance. High-density packaging of high-voltage semiconductors, such as 10 kV SiC MOSFETs, has the added challenge of maintaining low electric field concentration in order to prevent premature dielectric breakdown. This work proposes a wire-bond-less, sandwich structure with embedded...
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