We developed an apparatus for producing high-density hydrogen plasma. We confirmed that the temperatures of transition-metal films increased to above 800?C within 5 s when they were exposed to hydrogen plasma formed u...We developed an apparatus for producing high-density hydrogen plasma. We confirmed that the temperatures of transition-metal films increased to above 800?C within 5 s when they were exposed to hydrogen plasma formed using the apparatus. We applied this phenomenon to the selective heat treatment of W/Ni films deposited on n+4H-SiC wafers and formed nickel silicide electrodes. To utilize this method, we can perform the nickel silicidation process without heating the other areas such as channel regions and improve the reliability.展开更多
The behaviors of creeping streamer progressed in the narrow gap with the range of 0.1 mm to 0.2 mm between the pressboard mounted a BSE （back side electrode） and the acrylic resin plate were carried out in PFAE （pa...The behaviors of creeping streamer progressed in the narrow gap with the range of 0.1 mm to 0.2 mm between the pressboard mounted a BSE （back side electrode） and the acrylic resin plate were carried out in PFAE （palm fatty acid ester） oil under variable impulse voltage up to -4-140 kVpeak with ＋1.2/50 μs and ±1.2/1,000μs waveforms. The growth of positive and negative streamers depends on the gap space between two solid dielectrics. And the distinctive polarities of impulse voltage affect in the streamer length and flashover voltage between needle and counter electrodes as well. By decreasing the gap space, the flashover voltage largely increased while the mean velocity of positive streamer significantly decreased under the both polarities of impulse voltage. These results have been compared to commercial mineral oil （transformer oil： JIS-C2320）. It is shown that the behaviors of creeping discharge in both oils elegantly reveal the distinctive phenomena.展开更多
Excellent electrical properties and the impact of latest power devices for improving the efficiency of photovohaic（PV） inverters are presented.Power modules using SiC-MOSFET and SBD exhibit the possibility to realiz...Excellent electrical properties and the impact of latest power devices for improving the efficiency of photovohaic（PV） inverters are presented.Power modules using SiC-MOSFET and SBD exhibit the possibility to realize PV inverters with peak efficiency beyond 99%.Si-IGBT modules using reverse-blocking（RB）-IGBT have enabled to massproduce PV inverters with peak efficiency of 98.4%.Si superjunction（SJ）-MOSFET and discrete IGBT have enabled to improve the efficiency of small power PV inverters by 0.5 point.展开更多
We have directly investigated the chemical state of the Pd species in a real l-gas sensor device by examining the l-fluorescence X-ray absorption fine structure. The l-gas sensor device was heavily damaged by a heatin...We have directly investigated the chemical state of the Pd species in a real l-gas sensor device by examining the l-fluorescence X-ray absorption fine structure. The l-gas sensor device was heavily damaged by a heating process in which the temperature was ill-controlled, resulting in decrease of methane selectivity. We found that the Pd O in the fresh l-gas sensor was reduced to Pd metal particles as the methane selectivity decreased. Based on the investigation results, we modified the device structure so as to heat up homogeneously. The lifetime of the sensor was then successfully increased by more than 5 years.展开更多
A novel level-shift LDMOS （lateral double-diffused metal oxide semiconductor） structure with the HV （high voltage） -interconnection for a 600 V-HVIC （high voltage integrated circuit） on thick SOI （silicon on in...A novel level-shift LDMOS （lateral double-diffused metal oxide semiconductor） structure with the HV （high voltage） -interconnection for a 600 V-HVIC （high voltage integrated circuit） on thick SOI （silicon on insulator） is proposed. There are two original points in the proposed structure. One is the formation of the double floating p-layers under the HV-interconnection to prevent potential distribution in the drift from disturbing due to the HV-interconnection, and the other is a good combination between the LDMOS structure and multiple trench isolation to obtain the isolation performance over 600 V. From the proposed structure, the high blocking capability of the LDMOS, including both off- and on-breakdown voltages over 600 V and high hot carrier instability, and the isolation performance over 1,200 V can be obtained successfully. This paper will show numerical and experimental results in detail.展开更多
This paper presents practical distribution system equipment models such as various distributed generators, voltage regulators, and loads for fast three phase unbalanced load flow calculation in distribution systems. T...This paper presents practical distribution system equipment models such as various distributed generators, voltage regulators, and loads for fast three phase unbalanced load flow calculation in distribution systems. The method can calculate voltage and current of distribution systems, in which distributed generators are introduced. The calculation time of the proposed method is about 40 times faster than that of the Newton-Raphson method. Moreover, an introduction effect evaluation tool for distributed generators using the proposed three phase unbalanced load flow calculation is presented. It provides various functions such as a power system network diagram creation function and a voltage profile chart display function. Therefore, the introduction effect evaluation of distributed generators in distribution systems can be evaluated quite easily.展开更多
Energy storage systems with multilevel converters play an important role in modern electric power systems with large-scale renewable energy integration.This paper proposes a reverse-blocking modular multilevel convert...Energy storage systems with multilevel converters play an important role in modern electric power systems with large-scale renewable energy integration.This paper proposes a reverse-blocking modular multilevel converter for a battery energy storage system(RB-MMCBESS). Besides integrating distributed low-voltage batteries to medium or high voltage grids, with the inherited advantages of traditional MMCs, the RB-MMC-BESS also provides improved DC fault handling capability. This paper analyzes such a new converter configuration and its operating principles. Control algorithms are developed for AC side power control and the balancing of battery state of charge. The blocking mechanism to manage a DC pole-topole fault analyzed in depth. Comprehensive simulation results validate both the feasibility of the RB-MMC-BESS topology and the effectiveness of the control and fault handling strategies.展开更多
Power converters with insulated gate bipolar transistor(IGBT)are widely used in diverse industrial applications such as traction systems.As the IGBT is one of the most fragile components in power electronics converter...Power converters with insulated gate bipolar transistor(IGBT)are widely used in diverse industrial applications such as traction systems.As the IGBT is one of the most fragile components in power electronics converter,remaining useful life(RUL)prognostic of IGBT is important to guarantee system reliability.This paper presents a review of data-driven prognostic for IGBT RUL.In this paper,common data-driven prognostic methods are summarized.Features of data-driven prognostic approaches of IGBT are discussed,and main approaches are compared to each other.Four common problems of these schemes are presented and discussed.In addition,some other desirable studies to improve IGBT RUL estimation are proposed.展开更多
文摘We developed an apparatus for producing high-density hydrogen plasma. We confirmed that the temperatures of transition-metal films increased to above 800?C within 5 s when they were exposed to hydrogen plasma formed using the apparatus. We applied this phenomenon to the selective heat treatment of W/Ni films deposited on n+4H-SiC wafers and formed nickel silicide electrodes. To utilize this method, we can perform the nickel silicidation process without heating the other areas such as channel regions and improve the reliability.
文摘The behaviors of creeping streamer progressed in the narrow gap with the range of 0.1 mm to 0.2 mm between the pressboard mounted a BSE （back side electrode） and the acrylic resin plate were carried out in PFAE （palm fatty acid ester） oil under variable impulse voltage up to -4-140 kVpeak with ＋1.2/50 μs and ±1.2/1,000μs waveforms. The growth of positive and negative streamers depends on the gap space between two solid dielectrics. And the distinctive polarities of impulse voltage affect in the streamer length and flashover voltage between needle and counter electrodes as well. By decreasing the gap space, the flashover voltage largely increased while the mean velocity of positive streamer significantly decreased under the both polarities of impulse voltage. These results have been compared to commercial mineral oil （transformer oil： JIS-C2320）. It is shown that the behaviors of creeping discharge in both oils elegantly reveal the distinctive phenomena.
文摘Excellent electrical properties and the impact of latest power devices for improving the efficiency of photovohaic（PV） inverters are presented.Power modules using SiC-MOSFET and SBD exhibit the possibility to realize PV inverters with peak efficiency beyond 99%.Si-IGBT modules using reverse-blocking（RB）-IGBT have enabled to massproduce PV inverters with peak efficiency of 98.4%.Si superjunction（SJ）-MOSFET and discrete IGBT have enabled to improve the efficiency of small power PV inverters by 0.5 point.
基金High Energy Accelerator Organization under Proposal Number 2012G680
文摘We have directly investigated the chemical state of the Pd species in a real l-gas sensor device by examining the l-fluorescence X-ray absorption fine structure. The l-gas sensor device was heavily damaged by a heating process in which the temperature was ill-controlled, resulting in decrease of methane selectivity. We found that the Pd O in the fresh l-gas sensor was reduced to Pd metal particles as the methane selectivity decreased. Based on the investigation results, we modified the device structure so as to heat up homogeneously. The lifetime of the sensor was then successfully increased by more than 5 years.
文摘A novel level-shift LDMOS （lateral double-diffused metal oxide semiconductor） structure with the HV （high voltage） -interconnection for a 600 V-HVIC （high voltage integrated circuit） on thick SOI （silicon on insulator） is proposed. There are two original points in the proposed structure. One is the formation of the double floating p-layers under the HV-interconnection to prevent potential distribution in the drift from disturbing due to the HV-interconnection, and the other is a good combination between the LDMOS structure and multiple trench isolation to obtain the isolation performance over 600 V. From the proposed structure, the high blocking capability of the LDMOS, including both off- and on-breakdown voltages over 600 V and high hot carrier instability, and the isolation performance over 1,200 V can be obtained successfully. This paper will show numerical and experimental results in detail.
文摘This paper presents practical distribution system equipment models such as various distributed generators, voltage regulators, and loads for fast three phase unbalanced load flow calculation in distribution systems. The method can calculate voltage and current of distribution systems, in which distributed generators are introduced. The calculation time of the proposed method is about 40 times faster than that of the Newton-Raphson method. Moreover, an introduction effect evaluation tool for distributed generators using the proposed three phase unbalanced load flow calculation is presented. It provides various functions such as a power system network diagram creation function and a voltage profile chart display function. Therefore, the introduction effect evaluation of distributed generators in distribution systems can be evaluated quite easily.
基金supported by the State Key Laboratory of Large Electric Drive System and Equipment Technology(No.SKLLDJ042016005)the National Key Research and Development Program of China(No.2016YFE0131700)the National Natural Science Foundation of China(No.51577010)
文摘Energy storage systems with multilevel converters play an important role in modern electric power systems with large-scale renewable energy integration.This paper proposes a reverse-blocking modular multilevel converter for a battery energy storage system(RB-MMCBESS). Besides integrating distributed low-voltage batteries to medium or high voltage grids, with the inherited advantages of traditional MMCs, the RB-MMC-BESS also provides improved DC fault handling capability. This paper analyzes such a new converter configuration and its operating principles. Control algorithms are developed for AC side power control and the balancing of battery state of charge. The blocking mechanism to manage a DC pole-topole fault analyzed in depth. Comprehensive simulation results validate both the feasibility of the RB-MMC-BESS topology and the effectiveness of the control and fault handling strategies.
文摘Power converters with insulated gate bipolar transistor(IGBT)are widely used in diverse industrial applications such as traction systems.As the IGBT is one of the most fragile components in power electronics converter,remaining useful life(RUL)prognostic of IGBT is important to guarantee system reliability.This paper presents a review of data-driven prognostic for IGBT RUL.In this paper,common data-driven prognostic methods are summarized.Features of data-driven prognostic approaches of IGBT are discussed,and main approaches are compared to each other.Four common problems of these schemes are presented and discussed.In addition,some other desirable studies to improve IGBT RUL estimation are proposed.
