5,923 research outputs found
An isolated quasi-resonant multilevel dc-dc converter Multi-Phase Single-Stage Topology for 380 V VRM application
No full textThe power supply evolution for data centers and networking applications demands a continuous improvement in the efficiency at system and converter levels. Higher voltage distribution system and less conversion steps are necessary to increase the efficiency of the overall distribution system. To implement more efficient power conversion systems 48 V dc at rack level recently has been adopted ensuring higher overall efficiency, isolation design and phase shedding in light load; but rack-level dc distribution can be performed at a higher level of dc voltage such as 380 V dc. An advantage over 48 V dc distribution is that a more efficient ac/dc converter may beused, resulting in higher overall efficiency. For higher voltage dc distribution system a voltage regulator modules (VRM) is currently realized using a two-stage approach, with an intermediate 12 V dc bus. The challenge is to operate at high-efficiency with a single stage conversion directly from 380 V dc bus operating as high-voltage point-of-load (HV POL) converter, including a multi-phase approach and phase-shedding capabilities, maintaining high power density and dynamic performance comparable with 48 V VRM single-stage. This dissertation presents an innovative single-stage approach for the 380 V VRM based on a quasi-resonant multilevel topology constant on-time(COT) operation. The proposed topology inherently integrates the multiphase approach, providing fast phase shedding and flat high efficiency curves even at light load conditions. This is a unique advantage, which is not possible to establish in the two stage approach, which is very important in server architectures, and where high efficiency is required even at light load conditions. This dissertation analyses different high step down topologies including the aforementioned multilevel one, comprising a control architecture for fast transient response, the current sharing capabilities, and a solution for implementing the integrated magnetics. Experimental results show an efficiency of 93% for a 120 A, 380 V-1.8 V VRM power supply
Audiomobiles, Sculptures and Conundrums
No full textRoberto Gerhard was a pioneer of electronic music in England creating a number of substantial concert, theatre and radio works from as early as 1954. Gerhard’s electronic music is one of the richest repositories for understanding the development of the composer’s late compositional technique. Apart from the Symphony no.3, ‘Collages’, none of Gerhard’s electronic music is published. This paper will discuss aspects of Gerhard’s electronic music, focusing on Audiomobiles (1958-59) and Sculptures (1963)
Roberto Gerhard’s Sound Compositions: A Historical-Philological Perspective. Archive, Process, Intent and reenactment
No full textThis research advances the current state of knowledge in the field of early tape music both empirically and methodologically. The purpose of this study is to evaluate the impact that the electronic medium exerted in the musical thinking of Roberto Gerhard, one of the most outspoken, prolific and influential composers in the Spanish diaspora whose musical legacy, for the most part unknown, is a major landmark in the early history of electroacoustic music. Gerhard’s personal tape collection, one of the largest historical archives of its kind reported in the literature, is exceptional for both its antiquity (50+-year-old tapes) and its abundance of production materials. Through the digitisation and analysis of the composer’s tape collection this research argues that the empirical study of audio documents sets out a basis for a broader understanding of textual processes. More specifically, the research demonstrates that the reconstruction of works based on magnetic tape sketches is a powerful method to advance the understanding of early tape music. This research also examines Gerhard’s sound compositions in relation to the post-war context in which they were composed. Finally, this research presents performance documentation that proposes an approach to the electroacoustic music repertoire in which creativity is not at odds with rigor and critical discernment demonstrating that archival study can be closely aligned to the concept of re-enactment
SHSC: Non-Isolated High-Density 4:1 IBC For 48 V Applications
No full textThe rack-level 54/48 V bus architecture is an established standard in modern Data Centers, both in classical server applications and accelerator boards. The digital load supply (xPU/ASIC) is almost always provided through a Voltage Regulator Module (VRM), which is a multi-phase buck converter implementing the last stage of the power conversion. With modern technology, Voltage supply for the VRM is at its sweet spot between 6 V and 12 V, enabling the use of wide-spread, commercial power stages. To provide this Voltage rail to the VRM, a first stage connected to the 48 V bus is needed (Intermediate Bus Converter - IBC): as regulation is provided with high performance by the VRM, the IBC can be unregulated to enable very high power density. In this work the Authors present an unregulated, non-isolated 4:1 fixed-ratio Hybrid Switched Capacitor converter called SHSC. Detailed operation is shown, together with experimental results for a 40x18x8 mm discrete implementation providing up to 1.3 kW with a power density of 3.7 kW/in
Isolated resonant full-bridge converter with magnetic integration
No full textNowadays technological developments in modern microprocessors have brought better computing performance and have triggered the demand for high-efficiency power supply. The common trend in networking applications is to have a 48V dc distribution bus to increase system efficiency, while the supply of the microprocessor is usually obtained by a two-stage conversion process having an intermediate 12V dc bus. This paper presents a single-stage approach for the isolated voltage regulation module (VRM) based on a resonant topology that inherently integrates the multi-phase approach. In order to fit the layout constraints of the processor mother board, this paper also presents some magnetic architectures which integrate the magnetic parts. Compared to a classical discrete implementation, the proposed integrated magnetic structures have smaller total volume. In this paper we will compare the magnetic structures in the same application that is a processor power supply conversion from 48V bus. The proposed integrated magnetic architectures can be applied to other topologies as conventional ZVS full bridge. Experimental results on a 250A, 1.8 V multiphase isolated conversion are provided to show the effectiveness of the proposed solution
Filologia editoriale, Roberto Calasso in dialogo con Paola Italia e Francisco Rico
No full textPaola Italia e Francisco Rico intervengono sul libro di Roberto Calasso, presidente e fondatore di Adelphi Edizioni, L'impronta dell'editore, e discutono di problemi di filologia delle forme editoriali, dal punto di vista dell'autore, del lettore e dell'editore.Paola Italia and Francisco Ricos interview Roberto Calasso, Publisher, Writer, and Founder of Adelphi Edizioni, about his book: L'impronta dell'editore, talking about philology, publishing and editing, from the author, the reader and the publisher's point of view
An Isolated Multilevel Quasi-Resonant Multi-Phase Single-Stage Topology for 380 V VRM Applications
No full textRoberto Tibau and the process of making architecture
No full textEste estudo documenta a vida e a obra de Roberto José Goulart Tibau (1924-2003), arquiteto brasileiro. O objetivo fundamental - e mais importante - é reunir informações sobre os projetos e obras mais significativos desenvolvidos durante sua atividade profissional, tornando-os acessíveis através dessa pesquisa. O trabalho baseou-se em pesquisa bibliográfica, levantamento e registro das obras e projetos realizados, currículo profissional, e depoimento de Tibau, concedido ao autor, em 1998. Em Roberto Tibau e o fazer arquitetura são descritos os caminhos percorridos pelo arquiteto; o contexto histórico de sua formação e atuação profissional; a relação de sua produção arquitetônica com outras obras da época; e eventuais referências projetuais utilizadas na criação dos seus projetos. Este trabalho vem preencher uma lacuna bibliográfica considerável, trazendo à luz, a obra deste significativo arquiteto, que dedicou sua vida ao trabalho na prancheta, na qual deixou sua marca de humanista.This study documents the life and work of Roberto José Goulart Tibau (1924-2003), a Brazilian architect. It aims to collect information about the most significant projects developed during the years of his professional career, which will become available through this research. The present study based on bibliographical research, examination and registration of the projects executed by the architect, his resumé, and his testimonial to the author of this research, in 1998. In Roberto Tibau and the process of making architecture there is a description of the ways in which his projects were conceived; the historical context through his professional activity since graduation, the relation between his own production and the production of other architects of the same period, and the projecting references used for his creations. This research is also an attempt to fill a signicant bibliographical gap of architecture history in Brazil by bringing to light the work of this relevant architect, who dedicated his life to working on his drawing table, leaving to us his humanistic style
An Isolated Quasi-Resonant Multi-Phase Single-Stage Topology for 48 V VRM Applications
No full textIn order to increase the efficiency of modern microprocessors power supplies used in data centers, the 48-V dc distribution bus is gaining growing attention. For such applications, voltage regulation modules (VRMs) are currently obtained using two-stage conversion systems with an intermediate 12-V dc bus. This paper presents an innovative single-stage approach for the 48-V VRM based on a quasi-resonant constant on-time (COT) operation. The proposed topology inherently integrates the multiphase approach, providing fast phase shedding and flat high-efficiency curves even at light load conditions. This is a unique advantage, usually not available in the two-stage approach, that is very important in server architectures, where high efficiency is required even at light load conditions. The paper analyses the circuit topology, and proposes a control architecture for fast transient response, including the current sharing capabilities, and a solution for implementing the integrated magnetics. The digital controller has been implemented in 0.16-μ m lithography together with a digital pulse-width-modulation with a 195 ps resolution, and a 40 MS/s, 7-bit ADC. Experimental results show an efficiency of 93.1% for a 250 A, 1.8 V VRM, and of 93.2% for a 102 A, 1.2-V double data rate (DDR) power supply
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