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Power Devices (power + device)
Selected AbstractsDesign and performance analysis of impulse turbine for a wave energy power plantINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2005A. Thakker Abstract Wave energy is the most abundant source of renewable energy in the World. For the last two decades, engineers have been investigating and defining different methods for power extraction from wave motion. Two different turbines, namely Wells turbine and impulse turbine with guide vanes, are most commonly used around the world for wave energy power generation. The ultimate goal is to optimize the performance of the turbine under actual sea conditions. The total research effort has several strands; there is the manufacture and experimental testing of new turbines using the Wave Energy Research Team's (WERT) 0.6 m turbine test rig, the theoretical and computational analysis of the present impulse turbine using a commercial software package and finally the prediction of the performance of the turbine in a representative wave power device under real sea conditions using numerical simulation. Also, the WERT 0.6 m turbine test rig was upgraded with a data acquisition and control system to test the turbine in the laboratory under real sea conditions using the computer control system. As a result, it is proven experimentally and numerically that the turbine efficiency has been raised by 7% by reducing the hub-to-tip ratio from 0.7 to 0.6. Effect of tip clearance on performance of the turbine has been studied numerically and designed tip clearance ratio of 1% has been validated. From the numerical simulation studies, it is computed that the mean conversion efficiency is reduced around 5% and 4.58% due to compressible flow and damping effects inside OWC device. Copyright © 2005 John Wiley & Sons, Ltd. [source] Thermoelectric properties of Al1,xInxN and InOsNtprepared by reactive radio frequency sputteringPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003S. Yamaguchi Abstract With the aim of fabricating a thermoelectric power device using III-nitride semiconductors, we recently studied thermoelectric properties of Al1,xInxN and InOsNt prepared by radio-frequency sputtering. For Al0.55In0.45N, the maximum value of power factor was 3.63 × 10,4 W/mK2 at 873 K. For InO0.82N0.86, it was 3.75 × 10,4 W/mK2 at 973 K. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A high-efficiency diode-clamped linear amplifierELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 6 2008Hideaki Fujita Abstract This paper proposes a new power converter without any switching operation and which works as a linear amplifier. The main circuit of the proposed converter consists of series-connected MOSFETs, series-multi DC power supplies, and clamping diodes. The circuit configuration is similar to a diode-clamped multi-level inverter, except for using complementary power devices, which are n- and p-channel MOSFETs. One of the series-connected MOSFETs operates in an active state just like a linear amplifier, while the other MOSFETs operate in on or off states like an inverter circuit. As a result, the proposed converter achieves an acceptable efficiency as high as 90% without any ripples or harmonics caused by switching operation. Experimental results demonstrate that the proposed converter has the capability to drive a 2.2-kW three-phase induction motor. © 2008 Wiley Periodicals, Inc. Electron Comm Jpn, 91(6): 47,56, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10120 [source] A wide-band lumped circuit model of the terminal and internal electromagnetic response of coaxially insulated windings mounted on a coreEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 3 2003P. Holmberg This paper presents a wide-band lumped circuit model of coaxially insulated windings mounted on a core. The polyphase model can be used to simulate the terminal and internal electromagnetic response in DryformerTM, a new oil-free power transformer, and similar electromagnetic power devices. The circuit parameters are based on geometrical and material data. The simulated frequency and transient response of the lumped circuit is compared to measurements on a 20 MVA 140/6.6 kV three-phase transformer of the DryformerTM type. The comparison shows that the model can be used to estimate resonance frequencies and transient overvoltages in the transformer, although the damping is not accurately modelled. The influence of the core is discussed and investigated. [source] Environmentally-friendly Aspects and Innovative Lightweight Traction System Technologies of the Shinkansen High-speed EMUsIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 2 2008Yoshiyasu Hagiwara Member Abstract In 1964, the Tokaido Shinkansen marked the start of the world's first commercial service high-speed railway that operates at over 200 km/h. Since then, the Tokaido Shinkansen has demonstrated successful business and technological advancement. With the speeding-up of the Shinkansen, environmental matters such as noise and vibration have become critical issues. Measures taken to counter noise and vibration,such as weight reduction and aerodynamics,also effect global environmental measures to reduce energy consumption and CO2 emission. With the introduction of the Series 300, there was a system change of applying an AC drive system, and the lightweight body realized performance improvement over the earlier Series 0. The high-speed EMUs have readily taken advantage of technological innovation such as those achieved in electronics technology. In particular, an innovative AC drive system comprising a power converter with a GTO thyristor and asynchronous motors realized a high-performance and lightweight traction system for high-speed EMUs in the 1990s. Furthermore, recent innovations in electronics technology, such as low switching loss power devices and high-power permanent magnets, have improved the AC drive systems of the high-speed EMUs of the 21st century. This article starts out by introducing environmentally friendliness of the Shinkansen trains in terms of low energy consumption by means of traction system change, and then proceeds to describe the recent technological innovations that have given birth to lightweight traction systems, such as the Permanent Magnet Synchronous traction Motor (PMSM) and power converters with train-draft-cooling systems. The article concludes by summing up the environmentally friendly aspects of the Tokaido Shinkansen. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] Composite Zirconium Silicides Through an In Situ ProcessINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 1 2006Jérôme Canel Zirconium silicides are being investigated for use as neutron reflector materials for the next generation of nuclear power devices. Hot isostatically pressed monolithic Zr3Si2 and reactive sintered ZrXSiY composite are currently under development. The composite is obtained in situ and contains a ZrSi matrix embedding shell-like Zr, Zr2Si, and ZrSi2 domains with volume ratios depending on the initial Zr/Si ratio. Despite the lack of information on the mechanical properties of zirconium silicides, the composite structure is assumed to have enhanced fracture toughness; conditions to improve it further are discussed on the basis of microstructural observations of crack deflection. [source] A fast power loss calculation method for long real time thermal simulation of IGBT modules for a three-phase inverter systemINTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 1 2006Z. Zhou Abstract A fast power losses calculation method for long real time thermal simulation of IGBT module for a three-phase inverter system is presented in this paper. The speed-up is obtained by simplifying the representation of the three-phase inverter at the system modelling stage. This allows the inverter system to be simulated predicting the effective voltages and currents whilst using large time-step. An average power losses is calculated during each clock period, using a pre-defined look-up table, which stores the switching and on-state losses generated by either direct measurement or automatically based upon compact models for the semiconductor devices. This simulation methodology brings together accurate models of the electrical systems performance, state of the art-device compact models and a realistic simulation of the thermal performance in a usable period of CPU time and is suitable for a long real time thermal simulation of inverter power devices with arbitrary load. Thermal simulation results show that with the same IGBT characteristics applied, the proposed model can give the almost same thermal performance compared to the full physically based device modelling approach. Copyright © 2006 John Wiley & Sons, Ltd. [source] Model order reduction of linear and nonlinear 3D thermal finite-element description of microwave devices for circuit analysisINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2005Raphaël Sommet Abstract Electrothermal models of power devices are necessary for the accurate analysis of their performances. For this reason, this article deals with a methodology to obtain an electrothermal model based on a reduced model of a 3D thermal finite-element (FE) description for its thermal part and on pulsed electrical measurements for its electrical part. The reduced thermal model is based on the Ritz vector approach, which ensures a steady-state solution in every case. An equivalent SPICE subcircuit implementation for circuit simulation is proposed and discussed. An extension of the method to a nonlinear reduced model based on the Kirchoff transformation is also proposed. The complete models have been successfully implemented in circuit simulators for several HBT or PHEMT device structures. Many results concerning devices and circuits are presented, including simulation of both the static and dynamic collector-current collapse in HBTs due to the thermal phenomenon. Moreover, the results in terms of the circuit for an X-band high-power amplifier are also presented. As for the nonlinear approach, results concerning an homogeneous structure is given. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. [source] Inspection of Remanent Polarization in the Ferroelectric Ceramic PZT 95/5 Through Pyroelectric EffectJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2007Fu-Ping Zhang Shock-induced depoling of the ferroelectric (FE) ceramic PZT 95/5 is utilized in a number of pulsed power devices. Nondestructive testing of remanent polarization of PZT 95/5 is developed by pyroelectric effect in this paper. Approximately linear relation between the change of polarization during low- to high-temperature rhombohedral FE phase and the remanent polarization was found through pyroelectricity of a single piece of PZT 95/5 ceramics. The change of polarization of a prototype for shock-driven pulsed power during the FEHT,FELT phase transformation was also investigated through directly measuring the pyroelectric current. Results indicate that pyroelectric effect caused by the reversible FEHT,FELT phase transition could be used as a non-destructive inspection for the remanent polarization of a prototype about shock-driven pulsed power supply. [source] Reliability aspects of SiC Schottky diodesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2009Matthias Holz Abstract In recent years, silicon carbide (SiC) high-voltage power devices have gained an ever-increasing market share. The fast development of new device concepts and technologies, e.g. for SiC Schottky diodes, has led to devices with superior switching behaviour, which renders SiC power devices especially favourable for high-frequency applications. As of today, SiC devices enter various fields like, e.g. server power supplies, solar inverters, and drives. These applications pose quite different requirements not only on the electrical properties, but also on the long-term reliability of the devices. In this paper, we describe in detail how Infineon's SiC Schottky diodes excel the reliability requirements. We point out how material properties, device design and packaging technology affect the overall device reliability and how they can be optimized. In addition, we describe measurement results after stress tests that go far beyond standard stress tests according to JEDEC. E.g., we show that SiC devices can safely be operated at high voltage slopes of 120 V/ns. In addition, we show that the use of high performance die attach further improves the device properties and reliability. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||||||||