The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Lothar Heinemann - One of the best experts on this subject based on the ideXlab platform.
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An actively cooled High-? power, High-? frequency transformer with High-? insulation capability
APEC. Seventeenth Annual IEEE Applied Power Electronics Conference and Exposition (Cat. No.02CH37335), 2002Co-Authors: Lothar HeinemannAbstract:An actively cooled High-? power, High-? frequency transformer with High-? insulation capability for use in a High-? power multilevel converter is discussed. The transformer is designed for a power level of 350 kW and is realized with amorphous core material and coaxial windings. Special attention is paid to the insulation problem, since the Dielectric losses and the influence of the voltage waveform with very steep edges have to be investigated more in detail to guarantee a long lifetime of the device
R J Richter-sand - One of the best experts on this subject based on the ideXlab platform.
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High-? voltage, High-? power nested High-? voltage accelerator
Conference Record of the 1991 IEEE Particle Accelerator Conference, 1991Co-Authors: R. J. Adler, R J Richter-sandAbstract:The nested High-?voltage generator (NHVG) is a new type of accelerator based on the principle of the Faraday cage. It consists of a number of individual High-?voltage sections which are placed inside of the adjacent accelerator section, or nested one inside the other. Electronics internal to each of the NHVG states sets the voltage between the inner and outer Faraday cages to some voltage V. By building N stages and placing them one inside the other, one can produce a DC voltage The advantages of this type of accelerator are described along with the results of work with two small NHVG accelerators
Stephan Klemme - One of the best experts on this subject based on the ideXlab platform.
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High-?pressure High-?temperature tailoring of High-? Entropy Alloys for extreme environments
Journal of Alloys and Compounds, 2018Co-Authors: K. V. Yusenko, Sephira Riva, Kristina Spektor, Anna Pakhomova, Adam Tudball, Elena Bykova, Arno Rohrbach, Wilson A. Crichton, Ilya Kupenko, Stephan KlemmeAbstract:The exceptional performance of some High-? Entropy Alloys (HEAs) under extreme conditions holds out the possibility of new and exciting materials for engineers to exploit in future applications. In this work, instead of focusing solely on the effects of High-? temperature on HEAs, the effects of combined High-? temperature and High-? pressure were observed. Phase transformations occurring in a pristine HEA, the as-cast bcc–Al2CoCrFeNi, are heavily influenced by temperature, pressure, and by scandium additions. As-cast bcc–Al2CoCrFeNi and fcc–Al0.3CoCrFeNi HEAs are structurally stable below 60 GPa and do not undergo phase transitions. Addition of scandium to bcc–Al2CoCrFeNi results in the precipitation of hexagonal AlScM intermetallic (W-phase), which dissolves in the matrix after High-?pressure High-?temperature treatment. Addition of scandium and High-?pressure sintering improve hardness and thermal stability of well-investigated fcc- and bcc- HEAs. The dissolution of the intermetallic in the main phase at High-? pressure suggests a new strategy in the design and optimization of HEAs.
R. J. Adler - One of the best experts on this subject based on the ideXlab platform.
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High-? voltage, High-? power nested High-? voltage accelerator
Conference Record of the 1991 IEEE Particle Accelerator Conference, 1991Co-Authors: R. J. Adler, R J Richter-sandAbstract:The nested High-?voltage generator (NHVG) is a new type of accelerator based on the principle of the Faraday cage. It consists of a number of individual High-?voltage sections which are placed inside of the adjacent accelerator section, or nested one inside the other. Electronics internal to each of the NHVG states sets the voltage between the inner and outer Faraday cages to some voltage V. By building N stages and placing them one inside the other, one can produce a DC voltage The advantages of this type of accelerator are described along with the results of work with two small NHVG accelerators
Guo-quan Lu - One of the best experts on this subject based on the ideXlab platform.
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High-? Frequency , High-? Current Density Voltage Regulators High-? Frequency , High-? Current Density Voltage Regulators
Current, 2005Co-Authors: Jinghai Zhou, Fred C. Lee, Guo-quan LuAbstract:As a very special DC-DC converter, VRM (Voltage Regulator Module)\ndesign must follow\n\nthe fast-developing trend of microprocessors. The design challenges\nare the High-? current, High-?\n\ndi/dt, and stringent load-line requirement. When the energy is transferred\nfrom the input of a\n\nVRM, through the VRM, then through the power delivery path to the\nprocessor, it needs\n\nsufficient capacitors to relay this energy. The capacitors� number\nappears to be unrealistically\n\nlarge if we follow today�s approach for the future processors. High-?\nfrequency VRM with High-?\n\ncontrol bandwidth can solve this problem, however, the degradation\nof efficiency makes the\n\nconventional buck converter and the hard-switching isolated topologies\nincapable of operating at\n\nHigh-?er frequency. The research goal is to develop novel means that\ncan help a High-?outputcurrent\n\nVRM run efficiently at High-? frequency.\n\nA novel Complementary Controlled Bridge (CCB) self-driven concept\nis proposed. With the\n\nproposed self-driven scheme, the combination of the ZVS technique\nand the self-driven\n\ntechnique recycles the gate driving energy by making use of the input\ncapacitor of the secondaryside\n\nsynchronous rectifier (SR) as the snubber capacitor of the primary-side\nswitches. Compared\n\nto the external driver, the proposed converter can save driving loss\nand synchronous rectifier\n\nbody diode conduction loss. Additionally, compared to the existing\nlevel-shifted self-driven\n\nscheme for bridge-type symmetrical topologies, its gate signal ringing\nis small and suitable for\n\nHigh-?frequency applications.\n\nAlthough the CCB self-driven VRM reduces the switching frequency-related\nlosses\n\nsignificantly, the conduction loss is still High-?. Inspired by the\ncurrent-doubler concept, a novel\n\nZVS current-tripler DC-DC converter is proposed in this work. By utilizing\nmore SR devices to\n\nshare the current during the freewheeling period, the SR conduction\nloss is reduced. The currenttripler\n\nDC-DC converter has a delta/delta connected transformer that can be\nimplemented with\n\nintegrated magnetics. The transformer then becomes an integrated magnetic\nwith distributed\n\nwindings, which is preferred in High-? current applications. The current-tripler\nDC-DC converter in\n\niii\n\nfact meets the requirements for the CCB self-driven scheme. The two\nconcepts are then\n\ncombined with an integrated gate drive transformer.\n\nThe proposed CCB self-driven concept and current-tripler concept can\nboth be applied to the\n\n12V non-isolated VRMs. The proposed topology is basically a buck-derived\nsoft-switching\n\ntopology with duty cycle extension and SR device self-driven capabilities.\nBecause there is no\n\nisolation requirement, the SR gate driving becomes so simple that\nthe voltage at the\n\ncomplementary controlled bridge can be used to directly drive the\nSR gate. Both the gate driving\n\nloss and the SR body diode conduction loss are reduced. The proposed\ncircuit achieves similar\n\noverall efficiency to a conventional 300kHz buck converter running\nat 1MHz.\n\nAll the circuits proposed in this dissertation can use coupling inductors\nto improve both the\n\nsteady-state efficiency and dynamic performances. The essence of the\ncoupling inductors\n\nconcept is to provide different equivalent inductances for the steady\nstate and the transient.\n\nMoreover, when a current loop becomes necessary to achieve proper\ncurrent sharing among\n\nphases, the current loop sample hold effect will make it difficult\nto push the bandwidth. The\n\nsample hold effect is alleviated by the coupling inductors concept.\nA small-signal model is\n\nproposed to study the system dynamic performance difference with different\ncoupling inductor\n\ndesigns. As the verification, the coupling concept is applied to the\n12V non-isolated CCB selfdriven\n\nVRM and the bandwidth as High-? as one third of the switching frequency\nis achieved,\n\nwhich means a significant output capacitor reduction.