• 제목/요약/키워드: low loss

검색결과 5,068건 처리시간 0.034초

고속으로 운전되는 영구자석형 동기전동기의 철손 및 풍손 해석 (Analysis on the Core Loss and Windage Loss in Permanent Magnet Synchronous Motor for High-Speed Application)

  • 장석명;고경진;조한욱
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제55권10호
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    • pp.511-520
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    • 2006
  • Recently, more attention has been paid to the development of high-speed permanent magnet (PM) synchronous motors, since they are conductive to high efficiency, high power density, small size, and low weight. In high-speed PM machines, core loss and windage loss form a larger proportion of the total losses than usual in conventional mid- or low speed machines. This article deals with the analysis on the core loss and windage loss in PM synchronous motor for high-speed application. Using the data information from a manufacturer and non-linear curve fitting, this paper investigates the magnetic behavior and its core losses in the stator core using the electrical steels. And, the windage loss is calculated according to the variation of the rotational speed, motor inner pressure and temperature.

저신장율 대향류확산화염에서 진동불안정성을 갖는 에지화염의 동적거동 (Dynamic Behaviors of Oscillating Edge-Flame in Low Strain Rate Counterflow Diffusion Flames)

  • 박준성;김현표;박정;김정수;길상인
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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    • pp.65-72
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    • 2006
  • Experiments in methane-air low strain rate counterflow diffusion flames diluted with nitrogen have been conducted to study the behavior of flame extinction and edge flame oscillation in which flame length is less than the burner diameter and thus lateral conduction heat loss in addition to radiative heat loss could be remarkable at low global strain rates. Critical mole fraction at flame extinction is examined with velocity ratio and global strain rate. Onset conditions of edge flame oscillation and flame oscillation modes are also provided with global strain rate and added nitrogen mole fraction to fuel stream (fuel Lewis number). It is seen that flame length is closely relevant to lateral heat loss, and this affects flame extinction and edge flame oscillation considerably. Edge flame oscillations in low strain rate flames are experimentally described well and are categorized into three: a growing oscillation mode, a decaying oscillation mode, and a harmonic oscillation mode. The regime of flame oscillation is also provided at low strain rate flames. Important contribution of lateral heat loss even to edge flame oscillation is clarified.

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고자속밀도와 저손실 특성을 갖는 중주파수대 철심재료 개발 및 응용 (Development of Core Material with High Magnetic Induction and Low Iron Loss for Middle-Frequency Applications)

  • 조성수;한상옥
    • 전기학회논문지P
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    • 제58권2호
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    • pp.190-195
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    • 2009
  • Thin-gauged 3% silicon steel sheets having a highly grain-oriented texture have been developed as a core material for applications of middle-frequency (400 Hz ${\sim}$ 10 kHz) devices. The newly developed sheets with a tension coating showed an excellent reduction in iron loss at 400 Hz (iron loss at 1.0 T and 400 Hz = 4.677 W/kg, iron loss at 1.5 T and 400 Hz = 9.742 W/kg) due to high magnetic induction, $B_{10}$(measured induction at 1000 A/m), of over 1.9 T. In cases of frequencies below 400 Hz, magnetic induction, $B_{10}$, of the sample plays a major role to reduce its iron loss as excitation induction increases, whereas, in case of frequency of 1 kHz, thickness dependence becomes dominant due to a lower iron loss at relatively thinner sample. The sheets with a high magnetic induction, therefore, are favorable for high excitation induction (over 1.0 T) and low excitation frequency (below 400 Hz) applications, whereas the sheets that can reduce eddy current loss by reducing thickness or domain wall width are advantageous for low excitation induction (below 1.0 T) and high excitation frequency (around 1 kHz) applications.

저스위칭손실 및 저도통손을 갖는 양방향 ZVS PWM Sepic/Zeta 컨버터 (Bidirectional ZVS PWM Sepic/Zeta Converter with Low Conduction Loss and Low Switching Loss)

  • 팽성환;이병철;최성훈;김인동;노의철
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2005년도 전력전자학술대회 논문집
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    • pp.549-551
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    • 2005
  • Bidirectional DC/DC converters allows transfer of power between two dc sources, in either direction. Due to their ability to reverse the direction of flow of power, they are being increasingly used in many applications such as battery charger/dischargers, dc uninterruptible power supplies, electrical vehicle motor drives, aerospace power systems, telecom power supplies, etc. This paper proposes a new bidirectional Sepic/zeta converter. It has low swicthing loss and low conduction loss due to auxiliary communicated circuit and synchronous rectifier operation, respectively. Because of positive and buck/boost-like DC voltage transfer function(M=D/1-D), the proposed converter is very desirable for use in distributed power system . The proposed converter also has both transformerless version and transformer one.

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중합도에 따른 저점도 실리콘유의 유전 특성 (Dielectric Properties of Low Viscosity Silicone Oils with Degree of Polymerization)

  • 조경순
    • 한국전기전자재료학회논문지
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    • 제27권12호
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    • pp.847-851
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    • 2014
  • The characteristics of dielectric constant and $tan{\delta}$ of low viscosity silicone oils with changing degree of polymerization were investigated. The result shows dipole loss mechanism at low temperature range. The dielectric loss in the range of low frequencies are predominantly of ionic nature with temperature increase. The peak of dielectric loss is the detrapping of the electrons which is were trapped in the localized level of the silicone oils at the frequency of 30 kHz. The increase of ionic conduction is attributed to the presence of ionizable oxidation products and their increased dissociation feature. The activation energy ${\Delta}H$ and dipole moment ${\mu}_d$ were increased whit increasing degree of polymerization.

Ultrahigh Birefringence and Extremely Low Loss Slotted-core Microstructure Fiber in Terahertz Regime

  • Habib, Md. Ahasan;Anower, Md. Shamim;Hasan, Md. Rabiul
    • Current Optics and Photonics
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    • 제1권6호
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    • pp.567-572
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    • 2017
  • A novel slotted-core hexagonal photonic crystal fiber (PCF) for terahertz (THz) wave guiding is proposed in this paper. A trade-off managed between effective material loss (EML) and birefringence for efficient guidance of THz waves is illustrated in this article. The rectangular slot shaped air-holes break the symmetry of the porous-core which offers ultra-high birefringence of $8.8{\times}10^{-2}$. The proposed structure offers low bending loss of $1.07{\times}10^{-34}cm^{-1}$ and extremely low effective material loss (EML) of $0.035cm^{-1}$ at an operating frequency of 1.0 THz. In addition other guiding properties such as power fraction, dispersion and confinement loss are also discussed. The proposed THz waveguide can be effectively used for convenient transmission of THz waves.

Properties of Soft Magnetic Composite with Evaporated MgO Insulation Coating for Low Iron Loss

  • Uozumi, Gakuji;Watanabe, Muneaki;Nakayama, Rryoji;Igarashi, Kazunori;Morimoto, Koichiro
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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    • pp.1288-1289
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    • 2006
  • Innovative SMC with low iron loss was made from iron powders with evaporated MgO insulation coating. The coating had greater heat-resistance than conventional phosphatic insulation coating, which enabled stress relieving annealing at higher temperature. Magnetic properties of toroidal samples (OD35mm,ID25mm, t5) were examined. The iron loss at 50Hz for Bm = 1.5T was lower 50% of conventional SMC and was almost the same with silicon iron laminations(t0.35). It became clear that MgO insulation coating has enough heat resistance and adhesiveness to powdersurface to obtain innovative SMC with low iron loss.

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마이크로파 실내 배전용 저반사형 전력 분배 스위치 (Low Loss Power Dividing Switch for Indoor Microwave Power Distribution)

  • 최영규
    • 전기학회논문지
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    • 제62권1호
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    • pp.90-94
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    • 2013
  • A low loss power dividing switch in a indoor microwave power distribution system is proposed and designed with a various power dividing ratio. Switching characteristics are analyzed by use of the S-parameter of the switch. Newly proposed switch showed a very low return loss less than -30dB at the operating frequency of 2.45GHz. Three kinds of the switch in which we take out individually 1/2, 1/3 and 1/4 of the input power were fabricated, and measured the delivered, transmitted, and return loss power ratio. Simulated results showed that the lower power ratio is, the better accurate operating performance shows. This switch can switch the input power from 4.5% to 58% with the variance of 5% output power. The experimental results are in good agreement with the simulation within the return loss of 1%.

굽음손실이 적은 Bulged형 Abrupt Bend 구조의 제안 (Proposal of bulged-type abrupt bend structure with low bending loss)

  • 한상필;김창민
    • 전자공학회논문지D
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    • 제34D권8호
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    • pp.71-79
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    • 1997
  • Bulged-type bends with low bending loss are newly proposed, and the FD-BPM is made use of for designing optimum structure. How to evaluate bending loss of conventional bends and how to improve the bending structure based on the phase compensation concept are described in genral. Besides simulation results for the bulged-type bends, results for the coupled-type bends and the chamfered-type bends show the most superior performance in terms of not only the bending loss but also the design tolerance.

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RF-MEMS 소자를 위한 저손실 웨이퍼 레벨 패키징

  • 박윤권;이덕중;박흥우;송인상;김정우;송기무;박정호;김철주;주병권
    • 한국마이크로전자및패키징학회:학술대회논문집
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    • 한국마이크로전자및패키징학회 2001년도 추계 기술심포지움
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    • pp.124-128
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    • 2001
  • We apply for the first time a low cost and loss wafer level packaging technology for RF-MEMS device. The proposed structure was simulated by finite element method (FEM) tool (HFSS of Ansoft). S-parameter measured of the package shows the return loss (S11) of 20dB and the insertion loss (S21) of 0.05dB.

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