• Title/Summary/Keyword: Field variation

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유도전동기 회전자 시정수 변동에 강인한 간접 벡터제어 (A robust indirect vector control for the rotor time constant variation of induction motors)

  • 강현수;조순봉;현동석
    • 대한전기학회논문지
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    • 제45권3호
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    • pp.365-373
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    • 1996
  • This paper presents the effects of rotor time constant variation and the on-line tuning algorithm of the rotor time constant. If the value of the rotor time constant is set incorrectly, the IFOC (Indirect Field Oriented Control)scheme exhibits deteriorated performance according to the wrong slip command. These variation effects of the rotor time constant are caused by the slip calculator where it is known that the rotor time constant play an important role in the aligned rotor flux. Using the two torque angles (stationary torque angle, rotating torque angle), the variation of the rotor time constant is identified, and the rotor time constant of the controller is tuned to the proper value of the machine. As the result, with the proposed algorithm, the dynamics of the deteriorated IFOC system, where the rotor time constant is varied, is improved. For the purpose of the validity of this proposed algorithm, the computer simulations and the experiments have been performed and the explanation of the results is presented. (author). refs., figs., tab.

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Modeling Electrical Characteristics for Multi-Finger MOSFETs Based on Drain Voltage Variation

  • Kang, Min-Gu;Yun, Il-Gu
    • Transactions on Electrical and Electronic Materials
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    • 제12권6호
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    • pp.245-248
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    • 2011
  • The scaling down of metal oxide semiconductor field-effect transistors (MOSFETs) for the last several years has contributed to the reduction of the scaling variables and device parameters as well as the operating voltage of the MOSFET. At the same time, the variation in the electrical characteristics of MOSFETs is one of the major issues that need to be solved. Especially because the issue with variation is magnified as the drive voltage is decreased. Therefore, this paper will focus on the variations between electrical characteristics and drain voltage. In order to do this, the test patterned multi-finger MOSFETs using 90-nm process is used to investigate the characteristic variations, such as the threshold voltage, DIBL, subthreshold swing, transconductance and mobility via parasitic resistance extraction method. These characteristics can be analyzed by varying the gate width and length, and the number of fingers. Through this modeling scheme, the characteristic variations of multi-finger MOSFETs can be analyzed.

디지털 자기 컴퍼스의 자차와 편차 수정에 관한 연구 (A Study on the Correction Method for Deviations and Variations of Digital Magnetic Compass)

  • 임정빈;람파드하사하
    • 해양환경안전학회:학술대회논문집
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    • 해양환경안전학회 2006년도 추계학술발표회
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    • pp.137-141
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    • 2006
  • 선박용 디지털 컴퍼스를 사용하는 경우 선박의 진방위를 획득하기 위해서는 고정밀도의 자차와 편차가 필요하다. 편차는 지구자장의 주 자장과 경년변화에 대한 구면 지구 조화 모델을 이용한 WMM(World Magnetic Model)으로 예측 가능하였고, 자차는 포아송 방정식을 적용한 자차계수 합성과 분석 방법을 적용한 방법을 이용하여 획득 가능하였다. 실습선 '새누리호' 항해 중 디지털 컴퍼스에 편차와 자차를 가해준 결 과 정확한 진방위 획득이 가능하였다.

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밭경사에 따른 강우유출수 내의 비점오염물질 특성 비교 분석 (A study on Compare Characteristics of Nonpoint Source in Storm-water versus Steepness of Field Slope)

  • 김기철;최용훈;원철희;최중대
    • 한국수자원학회:학술대회논문집
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    • 한국수자원학회 2009년도 학술발표회 초록집
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    • pp.1093-1102
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    • 2009
  • This study was focused on analyse Nonpoint source characteristics from Flat slope field and Steep slope field. We performed Storm-water monitering for obtain flow data and concentration data. Totally, eleven times Event was occurred. We calculated EMC(Event Mean Concentration) and Pollutants Loads using data we obtained. As a result, steep slope field has more discharge than flat field. SS value, one of the water quality contents, has largest variation and T-N has least variation. There is runoff differences even though events has same rainfall. We assume that not only amount of Rainfall, but also Rainfall Duration Times, Intensity, Number of Previous Non-precipitation days can affect to Run-off.

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약계자 영역에서 유도전동기의 최대 토오크 운전 (Maximum Torque Control Of Induction Machines in Field Weakening Region)

  • 김상훈;설승기
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1994년도 하계학술대회 논문집 A
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    • pp.277-279
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    • 1994
  • In this paper, a novel field weakening scheme for the induction machine by the voltage control strategy is presented. The proposed algorithm ensures producing the maximum torque over the entire field weakening legion. Also by introducing the direct field-oriented control in the field weakening legion with large variation in machine parameters, the drive system can obtain the robustness to machine parameter variation. Moreover, by using estimated speed, sensorless speed control can be possible in very high speed lesion. Experimental results for a laboratory induction motor drive system confirm the validity or the proposed control algorithm.

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공간회로망법을 이용한 GIS내의 움직이는 도체이물질에 대한 전자계 해석 (Analysis of Electromagnetic Field by moving metal particle in GIS using SNM)

  • 임영환;박경수;최영환;최성열;고영호
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2001년도 하계학술대회 논문집 C
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    • pp.1670-1672
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    • 2001
  • In compared with air insulated switchgear GIS has a high efficiency and confidence. Insulation method using $SF_6$ gas has a very excellent insulation characteristics for high voltage equipment but has a characteristics that insulation heredity is changed for internal unequal electric field. So analysis of electromagnetic field in GIS is very important basic data for structure design and trouble diagnosis process. In compared with established method, SNM in this paper observes variation of the electromagnetic field with real time and get result very similar to measurement. In order to know the variation of electromagnetic field distribution for transient response for time and position, variations are observed when metal particles are moving fast.

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GIS 내부의 도체이물질에 의한 불평등 전계 해석 (Analysis of unequal electric field by metal particle in GiS)

  • 박경수;김진;이희복;고영호
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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    • pp.531-533
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    • 2000
  • In compared with air insulated switchgear, GIS has a high efficiency and confidence So the transformer substation can be reduced the size to 1/10. Insulation method using $SF_6$ gas has a very excellent insulation characteristics for high pressure equipment but has a characteristics that insulation heredity is changed for internal unequal electric field. So analysis of electromagnetic field in GIS is very important basic data for structure design and trouble diagnosis process. In compared with established method, SNM in this paper observes variation of the electromagnetic field with real time and get result very similar to measurement. In order to know the variation of electromagnetic field distribution for transient response for time and position, variations are observed when the spacer is bonded and metal particles are moving fast.

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선형적 물성변화를 고려하는 유한요소법을 이용한 2.5차원 전자탐사 수치모델링 (2.5 Dimensional Electromagnetic Finite Element Numerical modeling using linear conductivity variation)

  • 고광범;서백수
    • 산업기술연구
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    • 제18권
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    • pp.131-138
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    • 1998
  • Numerical modeling for electromagnetic exploration methods are essential to understand behaviours of electromagnetic fields in complex subsurfaces. In this study, a finite element method was adopted as a numerical scheme for the 2.5-dimensional forward problem. And a finite element equation considering linear conductivity variation was proposed when 2.5-dimensional differential equation to couple eletric and magnetic field was implemented. Model parameters were investigated for near-field with large source effects and far-field with responses dominantly by homogeneous half-space. Numerical responses by this study were compared with analytic solutions in homogeneous half-space and compared with other three dimensional numerical results.

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공간회로망법을 이용한 GIS 내부의 움직이는 도체이물질에 의한 불평등전계 해석 (Analysis of Unequal Electric Field by Moving Metal Particle in GIS Using SNM)

  • 박경수;최성열;고영호
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제51권2호
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    • pp.68-73
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    • 2002
  • In compared with air insulated switchgear, GIS has a high efficiency and confidence. Insulation method using $SF_6$ gas has a very excellent insulation characteristic for high voltage equipment but has a characteristic that insulation heredity is changed for internal unequal electric field. So analysis of time varying electromagnetic field in GIS is very important for structure design and trouble diagnosis process. In compared with established method, the SNM(Spatial Network Method) in this Paper can observe variation of electromagnetic field with real time and get result very similar to measurement. In order to Know variation of electromagnetic field distribution in fast moving particle, we make used of SNM.

음향 부양장(acoustic levitation field)에서 초음파 주파수(ultrasonic frequency)에 따른 단일 액적의 미립화 특성 (Effect of Ultrasonic Frequency on the Atomization Characteristics of Single Water Droplet in an Acoustic Levitation Field)

  • 서현규
    • 한국분무공학회지
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    • 제18권3호
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    • pp.126-131
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    • 2013
  • This paper describes the effect of ultrasonic frequency(f) on the atomization and deformation characteristics of single water droplet in an acoustic levitation field. To achieve this, the ultrasonic levitator that can control sound pressure and velocity amplitude by changing frequency was installed, and visualization of single water droplet was conducted with high resolution ICCD and CCD camera. At the same time, atomization and deformation characteristics of single water droplet was studied in terms of normalized droplet diameter($d/d_0$), droplet diameter(d) variation and droplet volume(V) variation under different ultrasonic frequency(f) conditions. It was revealed that increase of ultrasonic frequency reduces the droplet diameter. Therefore, it is able to levitate with low sound pressure level. It also induces the wide oscillation range, large diameter and volume variation of water droplet. In conclusion, the increase of ultrasonic frequency(f) can enhance the atomization performance of single water droplet.