• Title/Summary/Keyword: hysteresis characteristics

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Hysteresis Characteristics of Flux-Lock Type Superconducting Fault Current Limiter (자속구속형 고온초전도 사고전류제한기의 히스테리시스 특성)

  • Lim, Sung-Hun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.1
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    • pp.66-70
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    • 2007
  • For the design to prevent the saturation of the iron core and the effective fault current limitation, the analysis for the operation of the flux-lock type superconducting fault current limiter (SFCL) with consideration for the hysteresis characteristics of the iron core is required. In this paper, the hysteresis characteristics of the flux-lock reactor, which is an essential component of the flux-lock type SFCL, were investigated. Under normal condition, the hysteresis loss of the iron core in the flux-lock type SFCL does not happen due to its winding structure. From the equivalent circuit for the flux-lock type SFCL and the fault current limiting experiments, the hysteresis curves could be drawn. From the analysis for both the hysteresis curves and the fault current limiting characteristics due to the number of turns for the 1st and 2nd windings, the increase of the number of turns in the 2nd winding of the flux-lock type SFCL had a role to prevent the iron core from saturation.

Temperature dependent hysteresis characteristics of a-Si:H TFT (비정질 실리콘 박막 트랜지스터 히스테리시스 특성의 온도의존성)

  • 이우선;오금곤;장의구
    • Electrical & Electronic Materials
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    • v.9 no.3
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    • pp.277-283
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    • 1996
  • The temperature dependent characteristics of hydrogenerated amorphous silcon thin film transistor (a-Si:H TFT) with a bottom gate of N-Type <100> Si wafer were investigated. Drain current on the hysteresis characteristic curve showed an exponential variation. Hysteresis area of TFT increased with the gate voltage increased and decreased with the small gate voltage. According to the variation of gate voltages, drain current of TFT increased by temperature increase, and hysteresis characteristics mainly depended on the temperature increase. The hysteresis current showed negative characteristics curve over 383K. The hysteresis occurance area and the differences of forward and reverse sweep were increased at the higher temperature. Hysteresis current of I$_{d}$(on/off) ratio decreased at the lower temperature and increased at the higher temperature.e.

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Numerical Analysis Unsteady Flow Characteristics of the Wells Turbine (웰즈터빈의 비정상유동특성에 관한 수치해석)

  • 김태훈;박일규;이연원
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2001.05a
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    • pp.69-74
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    • 2001
  • The Wells turbine has hysteresis characteristics in a reciprocating flow. In this paper, in order to understand unsteady flow characteristics of the Wells turbine, a sinusoidal flow condition is simulated. The flow conditions and hysteresis characteristics, including blade thickness, are investigated over a period of time. The pressure distributions along the blade surface are investigated at mid-span to clarify the cause of the hysteresis. The result has shown that the hysteresis characteristics become more pronounced as blade thickness becomes larger. The occurrence of these characteristics depends on the varying behavior of wakes between an accelerating flow and a develerating flow.

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Characteristics Improvement of a PZT Actuator for Metal Printing (메탈 프린팅용 압전액추에이터의 특성개선)

  • Yun, S.N.;Ham, Y.B.;Kim, C.Y.;Park, P.Y.;Kang, J.H.
    • Journal of Power System Engineering
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    • v.9 no.4
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    • pp.162-167
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    • 2005
  • The purpose of this paper is to improve the hysteresis characteristics of a stack type piezoelectric actuator using system identification and tracking control. Recently, several printing methods that are cost less and faster than previous semiconductor processes have been developed for the production of electric paper and RFID(Radio Frequency IDentification). The system proposed in this study prints by spraying the molten metal. And this system consist of a nozzle, heating furnace, operating actuator and an XYZ 3-axis stage. As an operating system, the piezoelectric(PZT) actuator is a very useful tool for position control of the metal printing system. However, the PZT actuator has a hysteresis nonlinearity due to the ferroelectric characteristics of the PZT element. This hysteresis causes problem position control characteristics in the system and deteriorates the performance of the system. In this study, an investigation was conducted to improve the hysteresis characteristics of the PZT actuator that has an output displacement for the input voltage. In order to reduce the hysteresis nonlinearity of the PZT actuator, this proposed a inverse hysteresis model and a mathematic modeling method that can express the geometric relationship between voltage and displacement. In addition, system identification and PID control methods were examined. Also, it was confirmed that the proposed control strategy gives good tracking performance.

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The Simulation of the Characteristics of the Levitation Force in Superconductor Using 2D Slab Model (2차원 Slab 모델을 이용한 초전도체 부상력 특성의 시뮬레이션)

  • 유제환;임윤철
    • Tribology and Lubricants
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    • v.14 no.4
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    • pp.44-50
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    • 1998
  • This paper describes the simulation of the levitation force between permanent magnet and high Tc(critical temperature) superconductor(HTSC). Levitation force is evaluated numerically on the basis of the magnetic vector potential method and the critical state model. The superconductor is approximated to 2-D slab model. By performing computations, the following characteristics have been investigated: the process of the generation of hysteresis, the various hysteretic behaviors. The characteristics of hysteresis are important for the application to magnetic bearing, for the damping and the nonlinear stiffness is related to hysteresis.

Analysis on Hysteresis Characteristics of a Transformer Type Superconducting Fault Current Limiter (변압기형 초전도전류제한기의 히스테리시스 특성 분석)

  • Lim, Sung-Hun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.2
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    • pp.164-168
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    • 2010
  • The transformer is expected to be an essential component of a superconducting fault current limiter (SFCL) for both the increase of its voltage ratings and the simultaneous quench due to different critical current between high-$T_C$ superconducting (HTSC) elements comprising the SFCL. However, in order to perform the effective current limiting operation of the SFCL, the design for the SFCL considering the hysteresis characteristics of the iron core is required. In this paper, the influence of the hysteresis characteristics of the iron core comprising the transformer type SFCL on its current limiting characteristics was investigated. Through the comparative analysis on the hysteresis curves due to the ratio of the turn number between the 1st and the 2nd windings of the transformer, the proper design condition for the ratio of the turn number to achieve the effective current limiting operation of the transformer type SFCL could be obtained.

Hysteresis Reduction in piezoelectric actuator by a charge control method (전하 제어법을 이용한 압전 액추에이터의 이력저감)

  • Jeong Soonjong;Lee Daesu;Song Jaesung;Hong Younpyo;Kang Eungu;Choi Wonjong
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2005.05a
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    • pp.35-39
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    • 2005
  • This paper presents a method to reduce hysteresis in multilayer ceramic actuator by connecting the actuator with a capacitor in a series circuit. The change in hysteresis with respect to the capacitor was examined. $0.2Pb(Mg_{1/3}Nb_{2/3})O_3-0.8Pb(Zr_{0.475}Ti_{0.525})O_3$ ceramic material was used as a piezoelectric material for the actuator. Displacement of the actuator was measured in a capacitive gap sensor measuring system. In case of inserting a capacitor in a total circuit, hysteresis became dramatically decreased, and then finally the hysteresis value can be reduced below $0.2\%$. It was found in this present study that reducing the hysteresis in the actuator is dependent upon the characteristics of the capacitor in total circuit and also operating frequency.

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Finite Element Analysis for Hysteresis Motors (히스테리시스 전동기의 유한요소해석)

  • Hong, Sun-Ki;Won, Jong-Soo
    • Proceedings of the KIEE Conference
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    • 1995.11a
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    • pp.15-17
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    • 1995
  • Hysteresis motor is a synchronous machine which has simple structure and self-start characteristic but also has serious difficulties in numerical analysis. In this study, a finite element analysis for hysteresis motor considering the hysteresis characteristics is presented. The hysteresis model is the magnetization-dependent Preisach model which explains hysteresis phenomena very well. From this, we estimate the instantaneous torque, average torque and hysteresis loss of the rotor, considering slot and winding distribution.

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Improvement of Hysteresis Characteristics of Low Temperature Poly-Si TFTs (저온 Poly-Si TFT 소자의 Hysteresis 특성 개선)

  • Chung, Hoon-Ju;Cho, Bong-Rae;Kim, Byeong-Koo
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.2 no.1
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    • pp.3-9
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    • 2009
  • Although Active matrix organic light emitting diode (AMOLED) display has a better image quality in terms of viewing angle, contrast ratio, and response time than liquid crystal displays (LCDs), it still has some critical issues such as lifetime, residual images, and brightness non-uniformity due to non-uniformity in electrical characteristics of driving TFTs and IR drops on supplied power line. Among them, we improved irrecoverable residual images of AMOLED displays which is mainly related to the hysteresis characteristics of driving TFTs. We consider four kinds of surface treatment conditions before gate oxide deposition for improving hysteresis characteristics. We can reduce the hysteresis level of p-channel TFT to 0.23 V, interface trap states between the poly-Si layer and gate insulator to $3.11{\times}10^{11}cm^{-2}$, and output current variation of p-channel TFT to 3.65 % through the surface treatment using ultraviolet light and H2 plasma. Therefore, the recoverable residual image problem of AMOLED displays can be improved by surface treatment using ultraviolet light and $H_2$ plasma.

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Analysis of Hysteresis Characteristics of Flux-Lock Reactor (자속구속 리액터의 히스테리시스 특성 분석)

  • Lim, Sung-Hun;Choi, Hyo-Sang;Kang, Hyeong-Gon;Ko, Seok-Cheol;Lee, Jong-Hwa;Han, Byoung-Sung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.11a
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    • pp.255-258
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    • 2003
  • The hysteresis characteristics of flux-lock reactor, which is an essential component of flux-lock type superconducting fault current limiter (SFCL), was investigated. The hysteresis loss of iron core in flux-lock type SFCL does not happen due to its winding's structure especially in the normal state. From the equivalent circuit for the flux-lock type SFCL and the fault current limiting experiments, the hysteresis curves could be drawn. Through the hysteresis curves together with the fault current level due to the inductance ratio for the 1st and 2nd winding, the increase of the number of turns in the 2nd winding of the flux-lock type SFCL had a role to prevent the iron core from saturation.

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