• Title/Summary/Keyword: small-signal

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Analyzing of CDTA using a New Small Signal Equivalent Circuit and Application of LP Filters (새로운 소신호 등가회로를 활용한 CDTA의 해석 및 저역통과 필터설계)

  • Bang, Junho;Song, Je-Ho;Lee, Woo-Choun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.12
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    • pp.7287-7291
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    • 2014
  • A CDTA (current differencing transconductance amplifier) is an active building block for current mode analog signal processing with the advantages of high linearity and a wide frequency bandwidth. In addition, it can generate a stable voltage because all the differencing input current flows to the grounded devices. In this paper, a new small signal equivalent circuit is proposed to analyze a CDTA. The proposed small signal equivalent circuit provides greater precision in analyzing the magnitude and frequency response than its previous counterparts because it considers the parasitic components of the input, internal and output terminal. In addition, observations of the changes made in various devices, such as the resistor (Rz) confirmed that those devices heavily influence the characteristics of CDTA. The designed parameters of the proposed small signal equivalent circuit of the CDTA provides convenience and accuracy in the further design of analog integrated circuits. For verification purposes, a 2.5 MHz low pass filter was designed on the HSPICE simulation program using the proposed small signal equivalent circuit of CDTA.

Identification of Correlative Transmission Lines for Stability Prediction

  • Cho, Yoon-Sung;Gilsoo Jang;Kwon, Sae-Hyuk;Yanchun Wang
    • KIEE International Transactions on Power Engineering
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    • v.11A no.4
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    • pp.15-20
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    • 2001
  • Power system stability is correlated with system structure, disturbances and operating conditions, and power flows on transmission lines are closely related with those conditions. This paper proposes a methodology to identify correlative power flows for power system transient and small-signal stability prediction. In transient stability sense, the Critical Clearing Time is used to select some dominant contingencies, and Transient Stability Prediction index is proposed for the quantitative comparison. For small-signal stability discusses a methodology to identify crucial transmission lines for stability prediction by introducing a sensitivity factor based on eigenvalue sensitivity technique. On-line monitoring of the selected lines enables to predict system stability in real-time. Also, a procedure to make a priority list of monitored transmission lines is proposed. The procedure is applied to a test system, and it shows capabilities of the proposed method.

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An Accurate Small Signal Modeling of Cylindrical/Surrounded Gate MOSFET for High Frequency Applications

  • Ghosh, Pujarini;Haldar, Subhasis;Gupta, R.S.;Gupta, Mridula
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.12 no.4
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    • pp.377-387
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    • 2012
  • An intrinsic small signal equivalent circuit model of Cylindrical/Surrounded gate MOSFET is proposed. Admittance parameters of the device are extracted from circuit analysis and intrinsic circuit elements are presented in terms of real and imaginary parts of the admittance parameters. S parameters are then evaluated and justified with the simulated data extracted from 3D device simulation.

Identification of Correlative Transmission Lines for Stability Diagnosis of Power System (전력계통의 안정도 진단이 가능한 선로 선정에 관한 연구)

  • 조윤성;장길수;권세혁
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.5
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    • pp.271-278
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    • 2003
  • Power system stability is correlated with system structure, disturbances and operating conditions, and power flows on transmission lines are closely related with those conditions. This paper proposes a methodology to identify correlative power flows for power system transient and small-signal stability prediction. In transient stability sense, the Critical Clearing Time is used to select some dominant contingencies, and Transient Stability Prediction index is proposed for the quantitative comparison. For small-signal stability, this paper discusses a methodology to identify crucial transmission lines for stability Prediction by introducing a sensitivity factor based on eigenvalue sensitivity technique. On-line monitoring of the selected lines enables to predict system stability in real-time. Also, a Procedure to make a priority list of monitored transmission lines is proposed. The procedure is applied to a test system and the KEPCO systems in the year of 2003 and it shows capabilities of the proposed method

A New Small-Signal Modeling Method of HEMT Using Weakly Pinched-Off Cold-HEMT (약하게 핀치오프된 Cold-HEMT를 이용한 새로운 HEMT 소신호 모델링 기법)

  • 전만영
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.4
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    • pp.743-749
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    • 2003
  • By biasing the gate of cold-HEMT with a voltage slightly lower than the pinch-off point, a new small-signal modeling method that is free from gate degradation problem and requires no additional DC measurement is proposed in this paper. The method has shown excellent agreement between modeled and measured S-parameters up to 62 GHz at 49 different normal operating bias points.

An Analysis of ZVS Phase-Shift Full-Bridge Converter's Small Signal Model according to Digital Sampling Method (ZVS 위상천이 풀브릿지 컨버터의 디지털 샘플링 기법에 따른 소신호 모델 분석)

  • Kim, Jeong-Woo;Cho, Younghoon;Choe, Gyu-Ha
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.2
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    • pp.167-174
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    • 2015
  • This study describes how digital time delay deteriorates control performance in zero voltage switching (ZVS) phase-shifted full bridge (PSFB) converter. The small-signal model of the ZVS PSFB converter is derived from the buck-converter small-signal model. Digital time delay effects have been considered according to the digital sampling methods. The analysis verifies that digital time delays reduce the stability margin of the converter, and the double sampling technique exhibits better performance than the single sampling technique. Both simulation and experimental results based on 250 W ZVS PSFB confirm the validity of the analyses performed in the study.

Analysis of Oscillation Modes in Discrete Power Systems Including GTO Controlled STATCOM by the RCF Method (GTO 제어 STATCOM을 포함하는 이산 전력시스템의 RCF 해석법에 의한 진동모드 해석)

  • Kim, Deok-Young
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.5
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    • pp.829-833
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    • 2007
  • In this paper, the RCF method is applied to analyze small signal stability of power systems including GTO controlled parallel FACTS equipments such as STATCOM. To apply the RCF method in power system small signal stability problems, state transition equations of generator, controllers and STATCOM are presented. In eigenvalue analysis of power systems, STATCOM is modelled as the equivalents voltage source model and the PWM switching circuit model. As a result of simulation, the RCF method is very powerful to calculate the oscillation modes exactly after the switching operations, and useful to analyze the small signal stability of power systems with periodically operated switching devices such as STATCOM.

Ultrasonic Detection of Small Crack in Studs[Bolts] by Signal-Conditioning (초음파의 시그날콘디쇼닝에 의한 STUD[BOLT] 나사산의 미세결함 검출)

  • Suh, Dong-Man;Moon, Hong-Chin;Choi, Kyu-Hoon;Kim, Chong-Kyo
    • The Journal of the Acoustical Society of Korea
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    • v.9 no.3
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    • pp.31-41
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    • 1990
  • It is difficult to detect such flaws as stress-corrosion cracking or corrossion wastage(loss of bolt diameter) in the threads. In many cases the critical size of a flaw is very small(1-2mm order). This paper describes how it is possible to discriminate small flaw indications in threads using the time difference of thread signals [TDTS] by a signal-conditioning technique.

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Eigenvalue Analysis of Power Systems with Non-Continuous Operating Elements by the RCF Method : Modeling of the State Transition Equations (불연속 동작특성을 갖는 전력계통의 RCF법을 사용한 고유치 해석 : 상태천이 방정식으로의 모델링)

  • Kim Deok Young
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.54 no.2
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    • pp.67-72
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    • 2005
  • In conventional small signal stability analysis, system is assumed to be invariant and the state space equations are used to calculate the eigenvalues of state matrix. However, when a system contains switching elements such as FACTS devices, it becomes non-continuous system. In this case, a mathematically rigorous approach to system small signal stability analysis is by means of eigenvalue analysis of the system periodic transition matrix based on discrete system analysis method. In this paper, RCF(Resistive Companion Form) method is used to analyse small signal stability of a non-continuous system including switching elements. Applying the RCF method to the differential and integral equations of power system, generator, controllers and FACTS devices including switching elements should be modeled in the form of state transition equations. From this state transition matrix eigenvalues which are mapped to unit circle can be calculated.

Modeling of the State Transition Equations of Power Systems with Non-continuously Operating Elements by the RCF Method

  • Kim, Deok-Young
    • KIEE International Transactions on Power Engineering
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    • v.5A no.4
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    • pp.344-349
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    • 2005
  • In conventional small signal stability analysis, the system is assumed to be invariant and the state space equations are used to calculate the eigenvalues of the state matrix. However, when a system contains switching elements such as FACTS equipments, it becomes a non-continuous system. In this case, a mathematically rigorous approach to system small signal stability analysis is performed by means of eigenvalue analysis of the system's periodic transition matrix based on the discrete system analysis method. In this paper, the RCF (Resistive Companion Form) method is used to analyze the small signal stability of a non-continuous system including switching elements. Applying the RCF method to the differential and integral equations of the power system, generator, controllers and FACTS equipments including switching devices should be modeled in the form of state transition equations. From this state transition matrix, eigenvalues that are mapped into unit circles can be computed precisely.