• 제목/요약/키워드: EMF method

검색결과 373건 처리시간 0.021초

상호상관을 이용한 변압기내의 부분방전 위치측정 (Measurement of partial discharge point in power transformer using crosscorrelation)

  • 문영재;구춘근;정찬수;곽희로
    • 한국조명전기설비학회지:조명전기설비
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    • 제7권6호
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    • pp.34-41
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    • 1993
  • 전력 수요가 증가함에 따라 전력용 변압기의 용량이 커지고, 따라서 변압기사고의 파급효과가 커지게 된다. 본 논문은 전력용 변압기의 절연 열화에 의한 사고를 예방진단하기 위한 부분방전의 초음파 측정 기술을 응용하여, 초음파-초음파 측정법에 대한 부분방전점의 위치검출법을 연구하였다. 정확도를 높이기 위해 상호상관함수를 이용할 것을 제안하였으며 모의변압기에서 실험한 결과 만족할 만한 결과를 얻었다.

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브러시리스 직류 전동기용 새로운 센서리스 드라이브 개발에 관한 연구 (A study on the development of a new sensorless drive system for the brushless DC motors)

  • 장항제;이용순;김종선;유지윤;이광운;여형기;박정배
    • 전력전자학회논문지
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    • 제6권3호
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    • pp.223-230
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    • 2001
  • 구형파 브러시리스 직류전동기를 구동시키기 위해서는 전동기의 회전자 위치에 대한 정보를 아는 것이 필수적이다. 본 논문에서는 회전자 위치를 검출하기 위해 일반적으로 사용되는 홀센서나 엔코더를 이용하지 않고, 각 상을 저항으로 Y결선하여 만들어지는 단자의 전압에 포함되어 있는 비여자상의 역기전력을 이용하여 전동기의 회전자 위치를 검출하는 구형파 브러시리스 직류전동기용 센서리스 드라이브 시스템을 제안한다. 이를 위해 3상 2여자 선단부 유니폴라 PWM을 수행할 결우에 대한 각상의 단자전압 분석을 수행하고, 분석된 단자전압 파형으로부터 회전자 위치를 검출하는 방법을 제안한다. 그리고 이를 실제로 간단한 회로로 구현하였다. 실험에 사용된 전동기는 100W급이며 Power MOSFET으호 인버터를 구성하였으며 87c196mc 컨트롤러를 사용하여 제어기를 구성하였다.

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과풍속 영역에서의 약계자 제어를 이용한 풍력발전용 3상 PWM 컨버터의 출력제어 (Power Control of Three Phase PWM Converter for Small-scale Wind Power using Flux Weakening Control in Over Wind Speed Region)

  • 구현근;김재흥;이형욱;김장목
    • 전력전자학회논문지
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    • 제19권2호
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    • pp.149-156
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    • 2014
  • This paper proposes the battery charging algorithm for small-scale wind power generator using three phase PWM converter. it is impossible to control output power of the converter in over wind speed region since back EMF of PMSG is higer than battery voltage. Therefore, battery charging algorithm is proposed to expand battery charging over wind speed region. The suggested method is using the q-axis current for battery charging in the rated wind speed region. In the over wind speed region after it lower back EMF of PMSG using d-axis current it can control output power of the converter. The validity of the proposed algorithm are verified by experiments.

The Interaction between Hexadecyltrimethylammonium Bromide to Poly (Ethylene Glycol) with Different Molecular Weights and Some Schiff-Bases Investigated by Surfactant Ion Selective Electrode

  • Ghoreishi, Sayed Mehdi;Naeimi, Hossein;Navid, Mohammad Davodi
    • Bulletin of the Korean Chemical Society
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    • 제26권4호
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    • pp.548-552
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    • 2005
  • The interaction between ionic surfactants and different nonionic molecules and polymers are studied using ion surfactant selective electrode. From the experimental data, critical concentrations of the interaction and binding process are evaluated. The interaction between hexadecyltrimethylammonium bromide (HTAB) with polyethylene glycol (PEG) in three molecular weights (1000, 10000 and 100000) and also schiff-bases, 2-[2-carboxyphenyl nitrilomethylidyne]-phenol (ortho CNP), 2-[3-carboxyphenyl nitrilomethylidyne]-phenol (meta CNP)and 2-[4-carboxyphenyl nitrilomethylidyne]-phenol (para CNP) with the potentiometric method were investigated using HTAB membrane selective electrode. In the case of PEG with increasing molecular weights more interaction to HTAB occurs. The electromotive force (EMF) data also showed that interaction between para CNP with HTAB is more than the other schiff-bases. It seems this case related to less space interference of COOH group for that compound. The onset of binding ($T_1$) of course is the same for three schiffbase molecules.

병렬형 하이브리드 구동용 매입형 영구자석동기전동기 설계에 대한 연구 (A Study on the Design of Flat-Type IPMSM in Parallel Hybrid Traction Application)

  • 김기남;양해원
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제53권12호
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    • pp.718-724
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    • 2004
  • This study investigates the design factors of Interior Permanent Magnet Synchronous Motor(IPMSM) which is applied to Hybrid electric vehicle as a driving power. Recently, there are many studies of IPMSM for application to Hybrid Electric Vehicle, because IPMSM has characteristics of high torque, high power density and high efficiency which come from reluctance torque due to difference of inductance as well as magnet torque. This study analyzes the inductance and design characteristics of IPMSM by using finite element method and focuses on design and analysis of IPMSM which can operates with high efficiency at low speed range. For this embodiment, magnet shape is changed from conventional block type to arc type without any change of outline dimension of motor and this change of magnet shape makes it possible to increase back EMF and sinusoidal waveform. Analysis results are verified by test of improved and embodied motor. As a test result , increased back EMF and sharply decrease of harmonics are secured and through this contribution of reduced fuel consumption of Hybrid electric vehicle is expected.

5상 유도전동기의 속도응답특성 개선을 위한 직접토크제어 시스템 (A Direct Torque Control System for Improving Speed Response of Five-Phase Induction Motor)

  • 김민회;최성운
    • 조명전기설비학회논문지
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    • 제26권1호
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    • pp.66-74
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    • 2012
  • This paper propose a improved direct torque control(DTC) system for improving operation of five-phase squirrel-cage induction motor(IM). A five-phase IM drives present unique characteristics due to the additional degrees of freedom and also drives possess many others advantage compared with the traditional three-phase motor drive system, such as reducing a amplitude of torque pulsation and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated windings and the produced back-electromotive force(EMF) is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus third harmonic of currents, there is necessary to controlled 3rd harmonic current. Also a DTC method is advantageous when it is applied to the five-phase IM, because the five-phase inverter provides 32 space vectors in comparison to 8 space voltage vectors into the three-phase inverter drive system. For presenting the superior performance of the proposed DTC, experimental results of speed control are presented using a 32-bit fixed point TMS320F2812 DSP with 1.5[hp] IM.

박막 리튬이온전도체를 이용한 전위차 CO2 가스센서 (Potentiometric CO2 gas sensor based on the thin film electrolyte of Li+ ion conductor)

  • 노효섭;최광표;송호근;박진성
    • 센서학회지
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    • 제14권4호
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    • pp.258-264
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    • 2005
  • Li+-ion conducting ($Li_{3}PO_{4}$) thin films with thickness of $0.3{\mu}m$, $0.65{\mu}$, $1.2{\mu}$ were deposited on $Al_{2}O_{3}$ substrate at room temperature by thermal evaporation. They were sintered at $700^{\circ}C$ and $800^{\circ}C$ for 2 hours, respectively. Reference electrode and sensing electrode were printed on Au-electrode by silk printing method. The EMF and the ${\Delta}EMF$/dec were increased with increasing the electrolyte thickness and sintering temperature. The sample sintered at $800^{\circ}C$ was shown a good response and recovery characteristics more than those sintered at $700^{\circ}C$. The Nernst's slop of 75 mV per decade was obtained at operating temperature of $500^{\circ}C$.

전자기력 자유벌지 실험을 위한 성형코일 설계 및 3-D 해석비교 (Design of a Free Bulge Test Coil Using Electromagnetic Forces and Comparison between Experimental and Numerical Results)

  • 김홍교;노학곤;강범수;김정
    • 소성∙가공
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    • 제23권7호
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    • pp.431-438
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    • 2014
  • For electromagnetic forming(EMF) the most important feature is a forming coil which creates the electromagnetic force(Lorentz force), using current density and a magnetic field. Most previous papers have concentrated on the final configuration of the blank or the efficiency of EMF process. Studies focused on the design parameters affected by the forming coil performance have not been conducted. In order to design a suitable forming coil for an object, the current study uses LS-DYNA EM-Module to not only optimize the coil but also to examine the effect of coil performance. By this method a suitable forming coil was made and tested to determine whether or not good formability was achieved in a free bulge test Numerical analysis was also used. The workpiece was Al 1100-O with a thickness of 1.27mm and the coil was made from copper CW004A, which has good electrical conductivity and is suitable for electrical components.

Improved Torque Calculation of High Speed Permanent Magnet Motor with Compressor Loads Using Measured Power Factor Angle and Analytical Circuit Parameters

  • Choi, Jang-Young;Jang, Seok-Myeong;Lee, Sung-Ho
    • Journal of international Conference on Electrical Machines and Systems
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    • 제2권2호
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    • pp.159-164
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    • 2013
  • Difficulty of torque measurements in high-speed permanent magnet (HSPM) motors has necessitated the development of improved torque calculations. Hence, this paper presents an analytical torque calculation of a high speed permanent magnet (HSPM) motor based on the power factor angle. On the basis of analytical magnetic field solutions, the equations for circuit parameters such as back-emf and synchronous inductance are derived analytically. All analytical results are validated extensively by non-linear finite element (FE) calculations and measurements. The internal angle (${\delta}$) between the back-emf and the phase current is calculated according to the rotor speed by using analytical circuit parameters and the measured power factor because this angle is not measured but estimated in case of sensorless drive of the HSPM motor, significantly affecting torque calculation. Finally, the validity of the torque analysis method proposed in this paper is confirmed, by showing that the torque calculated on the basis of the internal angle is in better agreement with the measurements.

고조파 전류를 이용한 영구자석형 동기 전동기의 토크 리플 저감 (Torque Ripple Reduction for Permanent Magnet Synchronous Motor using Harmonic Current Injection)

  • 권순오;이정종;이근호;홍정표
    • 전기학회논문지
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    • 제58권10호
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    • pp.1930-1935
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    • 2009
  • This paper deals with the torque ripple reduction of permanent magnet synchronous motor using harmonic current injection. Torque ripple of electric motor reduces system stability and performances, therefore efforts to reduce torque ripple are exerted in the design process. Torque ripple can be reduced by appropriate pole/slot combination, skew of rotor or stator, design of magnetic circuit, etc. In addition, torque ripple can be also reduced by input voltage and current, and many researches have been conducted to reduce torque ripple for six-step drive. Torque ripple reduction for current vector controlled permanent magnet synchronous motor also have been conducted and verified by investigating back emf wave form. Torque ripple reduction in this paper started from getting torque profile according to input current and electrical angle calculated by FEA, then instantaneous currents at each electrical angles for constant torque are calculated and applied to experiments. Therefore, 0% of torque ripple can be obtained theoretically with harmonic current injection. In order to maximize the effect of torque ripple reduction, a BLDC motor having high harmonic component of back emf is chosen. With sinusoidal current drive, over 100% of torque ripple is obtained initially, then 0.5 % of torque ripple is obtained by FEA using harmonic current injection. The effect is verified by experiment and the presented method can be effectively applicable to Electric Power Steering(EPS).