1,721,087 research outputs found
Design aspects for a robust snubberless power converter with Si and SiC Power MOSFETs
No full textA number of harsh-environment high-reliability applications are undergoing substantial electrification. The converters operating in such systems need to be designed to meet both
stringent performance and reliability requirements. This work focuses on a dc-dc converter for novel avionic applications and considers both new semiconductor technologies and the
application of design techniques to ensure that robustness is maximized and stress levels minimized. In this respect, close attention is paid to the thermal management and an approach
for the heatsink design aided by finite element modeling is shown
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Single pulse avalanche robustness and repetitive stress ageing of SiC power MOSFETs
Full text linkThis paper presents an extensive electro-thermal characterisation of latest generation silicon carbide (SiC) Power MOSFETs under unclamped inductive switching (UIS) conditions. Tests are carried out to thoroughly understand the single pulse avalanche ruggedness limits of commercial SiC MOSFETs and assess their aging under repetitive stress conditions. Both a functional and a structural characterisation of the transistors is presented, with the aim of informing future device technology development for robust and reliable power system development
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Highly integrated low-inductive power switches using double-etched substrates with through-hole viases
No full textThis work proposes the design and assembly of a very low inductance half-bridge power switch. It uses latest generation Infineon Technologies® 70μm thin IGBTs and diodes rated at 600 V/175 °C. The integration relies on state-of-the-art ceramic substrate technology, featuring double-etched patterned copper tracks enabling a fully bond-wire-less interconnection scheme; through-hole conducting viases are also present in the ceramic substrates for vertical current conduction, which enables the introduction of a ground-plane structure within the switch, with greatly reduced overall values of parasitic inductance. Moreover, the switch features double-sided cooling. The paper also proposes an outline of system-level integration solutions for ensuring that low-inductance characteristics at switch level are not lost when interconnecting to input filter and load
Soft-starting procedure for dual active bridge converter
No full textDual Active Bridge converter is extensively used to manage the power flow in high power and high density applications, as energy storage systems, renewable sources integration and electrical vehicles. This paper focuses on a digital starting process — suitable for all operating conditions — aiming at minimizing the inrush current at the turn on. The output voltage is initially built up by the secondary side body diodes, then phase-shift control is enabled and the reference is smoothly increased till the nominal value. A FPGA controlled 1.2kW 270V/28V converter is developed and experimental results are provided to assess the proposed method
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Performance evaluation of a 3-level ANPC photovoltaic grid-connected inverter with 650V SiC devices and optimized PWM
Full text linkPhotovoltaic (PV) energy conversion has been on the spotlight of scientific research on renewable energy for several years. In recent years the bulk of the research on PV has focused on transformerless grid-connected inverters, more efficient than traditional line transformer-based ones, but more critical from a power quality point of view, especially in terms of ground leakage current. Neutral point clamped (NPC) inverters have recently gained interest due to their intrinsically low ground leakage current and high efficiency, especially for MOSFET-based topologies. This paper presents an active NPC (ANPC) topology equipped with 650 V SiC MOSFETs, with a new modulation strategy that allows to reap the benefits of the wide-bandgap devices. An efficiency improvement is obtained due to the parallel operation of two devices during the freewheeling intervals. Simulations and experimental results confirm the effectiveness of the proposed converter
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