The Experts below are selected from a list of 124896 Experts worldwide ranked by ideXlab platform
Fred C. Lee - One of the best experts on this subject based on the ideXlab platform.
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High frequency bus converter with low Loss integrated matrix transformer
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, 2012Co-Authors: David Reusch, Fred C. LeeAbstract:The trend in isolated DC/DC converters is increasing output power demands and higher operating frequencies. Improved topologies and semiconductors can allow for lower Loss at higher frequencies. A major barrier to further improvement is the transformer design. With high current levels and high frequency effects the transformers can become the major Loss Component in the circuit. High values of transformer leakage inductance can also greatly degrade the performance of the converter. Matrix transformers offer the ability to reduce winding Loss and leakage inductance. This paper will study the impact of increased switching frequencies on transformer size and explore the use of matrix transformers in high current high frequency isolated applications. This paper will also propose an improved integrated matrix transformer design that can decrease core Loss and further improve the performance of matrix transformers.
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High frequency bus converter with integrated matrix transformers for CPU and telecommunications applications
2010 IEEE Energy Conversion Congress and Exposition ECCE 2010 - Proceedings, 2010Co-Authors: David Reusch, Fred C. LeeAbstract:The trend in intermediate bus architectures is increasing output power demands and higher operating frequencies. Improved topologies and semiconductors can allow for lower Loss at higher frequencies. A major barrier to further improvement is the transformer design. With high current levels and high frequency effects the transformers can become the major Loss Component in the circuit. High values of transformer leakage inductance can also greatly degrade the performance of the converter. Matrix transformers offer the ability to reduce winding Loss and leakage inductance. This paper will study the use of matrix transformers for a 600-W, 12-V/50A bus converter and identify the optimal number of matrix transformers. This paper will also propose an improved integrated matrix transformer design that can decrease core Loss and further improve the performance of matrix transformers.
Kazuhiko Hayashi - One of the best experts on this subject based on the ideXlab platform.
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transport current ac Losses of high tc superconducting tapes exposed to ac magnetic field
presented at CEC ICMC Portland USA July 1997, 1998Co-Authors: S Fukui, Y Kitoh, T Numata, Osami Tsukamoto, Jun Fujikami, Kazuhiko HayashiAbstract:A new measurement method is developed to properly measure transport current AC Losses of high-Tc superconducting tapes which are subject to external magnetic field generated by adjacent tapes in multiple tapes assembled conductor. It has been pointed out that to correctly measure the AC Losses of the tape, the voltage measurement loop should include the magnetic flux over a distance much larger than the tape width. However, this wide voltage loop needs wide space and picks up spurious Loss caused by adjacent tapes when multiple tapes are assembled. In our arrangement, the leads from voltage taps on the tape are wound on a cylindrical surface enclosing the tape. This method can save space for voltage leads and avoid spurious Loss Component caused by the magnetic field of the other tape. In the paper, details of our measurement arrangement are explained and the validity of our method is investigated by theoretical and numerical analyses and an experiment. It is demonstrated that our method is effective.
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transport current ac Losses of high tc superconducting tapes exposed to ac magnetic field study on a new measurement method
Advances in cryogenic engineering, 1998Co-Authors: S Fukui, Y Kitoh, T Numata, Osami Tsukamoto, Jun Fujikami, Kazuhiko HayashiAbstract:A new measurement method is developed to properly measure transport current AC Losses of high-Tc superconducting tapes which are subject to external magnetic field generated by adjacent tapes in multiple tapes assembled conductor. It has been pointed out that to correctly measure the AC Losses of the tape, the voltage measurement loop should include the magnetic flux over a distance much larger than the tape width. However, this wide voltage loop needs wide space and picks up spurious Loss caused by adjacent tapes when multiple tapes are assembled. In our arrangement, the leads from voltage taps on the tape are wound on a cylindrical surface enclosing the tape. This method can save space for voltage leads and avoid spurious Loss Component caused by the magnetic field of the other tape. In the paper, details of our measurement arrangement are explained and the validity of our method is investigated by theoretical and numerical analyses and an experiment. It is demonstrated that our method is effective.
David Howe - One of the best experts on this subject based on the ideXlab platform.
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Analytical prediction of eddy-current Loss in modular tubular permanent-magnet machines
IEEE Transactions on Energy Conversion, 2005Co-Authors: Yacine Amara, J.-j. Wang, David HoweAbstract:The paper describes an analytical technique for pre- dicting the eddy-current Loss in the moving armature of a tubular permanent magnet machine. This Loss Component is usually ne- glected in conventional tubular permanentmagnet machines since high-order time harmonics in the stator current waveform and space harmonics in the winding magnetomotive force (MMF) dis- tribution are generally considered to be insignificant. However, a relatively new topology of tubular permanent magnet machine, sometimes referred to as “modular,” has emerged in which the fundamental Component of the stator MMF has fewer poles than that of the permanent-magnet armature, the thrust force being de- veloped by the interaction between a higher orderMMFharmonic and the permanent magnet field. Thus, the presence of lower and higher order space harmonics in the windingMMFdistribution of amodular machinemay gives rise to a significant eddy-current Loss in themoving-magnet armature. An analyticalmodel is developed to predict the eddy currents which are induced in the magnets, as well as inany electrically conducting supporting tube whichmay be employed, and to quantify the effectiveness of axially segmenting the magnets in reducing the eddy-current Loss. The validity of the developed model, which is also applicable to conventional designs of tubular permanent-magnet machine, is verified by time-stepped transient finite-element analysis (FEA).
David Reusch - One of the best experts on this subject based on the ideXlab platform.
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High frequency bus converter with low Loss integrated matrix transformer
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC, 2012Co-Authors: David Reusch, Fred C. LeeAbstract:The trend in isolated DC/DC converters is increasing output power demands and higher operating frequencies. Improved topologies and semiconductors can allow for lower Loss at higher frequencies. A major barrier to further improvement is the transformer design. With high current levels and high frequency effects the transformers can become the major Loss Component in the circuit. High values of transformer leakage inductance can also greatly degrade the performance of the converter. Matrix transformers offer the ability to reduce winding Loss and leakage inductance. This paper will study the impact of increased switching frequencies on transformer size and explore the use of matrix transformers in high current high frequency isolated applications. This paper will also propose an improved integrated matrix transformer design that can decrease core Loss and further improve the performance of matrix transformers.
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High frequency bus converter with integrated matrix transformers for CPU and telecommunications applications
2010 IEEE Energy Conversion Congress and Exposition ECCE 2010 - Proceedings, 2010Co-Authors: David Reusch, Fred C. LeeAbstract:The trend in intermediate bus architectures is increasing output power demands and higher operating frequencies. Improved topologies and semiconductors can allow for lower Loss at higher frequencies. A major barrier to further improvement is the transformer design. With high current levels and high frequency effects the transformers can become the major Loss Component in the circuit. High values of transformer leakage inductance can also greatly degrade the performance of the converter. Matrix transformers offer the ability to reduce winding Loss and leakage inductance. This paper will study the use of matrix transformers for a 600-W, 12-V/50A bus converter and identify the optimal number of matrix transformers. This paper will also propose an improved integrated matrix transformer design that can decrease core Loss and further improve the performance of matrix transformers.
Peter Omand Rasmussen - One of the best experts on this subject based on the ideXlab platform.
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Theoretical and Experimental Loss and Efficiency Studies of a Magnetic Lead Screw
IEEE Transactions on Industry Applications, 2015Co-Authors: Nick Ilsoe Berg, Rasmus Koldborg Holm, Peter Omand RasmussenAbstract:This paper investigates mechanical and magnetic Losses in a magnetic lead screw (MLS). The MLS converts a low-speed high-force linear motion of a translator into a high-speed low-torque rotational motion of a rotor through helically shaped magnets. Initial tests performed with a novel 17-kN demonstrator and a simplified motor model showed an efficiency of only 80% at low load; however, it was expected that the efficiency should be above 95%. For understanding and future optimization, a detailed study of the Loss in the MLS is presented with the aim of identifying and segregating various Loss Components that was not accounted for in previous results. This is done through theoretical Loss calculations and various experiments. It is concluded that the linear guide is the dominating Loss Component in the MLS demonstrator, whereas the Losses in the axial thrust bearing is not as dominant as expected; furthermore, an efficiency above 94% was measured.
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Theoretical and experimental Loss and efficiency studies of a magnetic lead screw
2013 IEEE Energy Conversion Congress and Exposition, 2013Co-Authors: Nick Ilsoe Berg, Rasmus Koldborg Holm, Peter Omand RasmussenAbstract:This paper investigates mechanical and magnetic Losses in a magnetic lead screw (MLS). The MLS converts a low speed high force linear motion of a translator into a high speed low torque rotational motion of a rotor through helically shaped magnets. Initial tests performed with a novel 17 kN demonstrator and a simplified motor model showed an efficiency of only 80 % at low load, however it was expected that the efficiency should be above 95 %. For understanding and future optimization a detailed study of the Loss in the MLS is presented with the aim of identifying and segregate various Loss Components which was not accounted for in previously results. This is done through theoretical Loss calculations and various experiments. It is concluded that the linear guide is the dominating Loss Component in the MLS demonstrator, while the Losses in the axial thrust bearing is not as dominant as expected, further an efficiency above 94 % was measured.
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Development of a high-performance magnetic gear
IEEE Transactions on Industry Applications, 2005Co-Authors: Peter Omand Rasmussen, Petet Omand Rasmussen, Orla Nielsen, Frank Thorleif Jorgensen, Frank Thorleif Joergensen, Torben Ole Andersen, Ole S. NielsenAbstract:This paper presents calculation and measurement results of a high-performance permanent-magnetic gear. The analyzed permanent-magnetic gear has a gear ratio of 5.5 and is able to deliver 27 N·m. The analysis has shown that special attention needs to be paid to the system where the gear is to be installed because of a low natural torsion spring constant. The analyzed gear was also constructed in practice in order to validate the analysis and predict the efficiency. The measured torque from the magnetic gear was only 16 N·m reduced by the large end-effects. A systematic analysis of the Loss Components in the magnetic gear is also performed in order to figure out why the efficiency for the actual construction was only 81%. A large magnetic Loss Component originated in the bearings, where an unplanned extra bearing was necessary due to mechanical problems. Without the Losses of magnetic origin in the bearings and less end-effects caused by relatively short stack, an impressive efficiency estimated at 96% can be obtained. Comparison with classical mechanical gears has shown that the magnetic gear has a better efficiency and a comparable torque per volume density. Finally, it is concluded that the results in this paper may help to initiate a shift from mechanical gears to magnetic gears.
