• Title/Summary/Keyword: equivalent series resistance

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A Study on the Elimination of Temporary overvoltage Due to Ferroresonance at Gas Insulated Switchgear (Gas 색연(絶綠) 개폐장치(開閉裝置)의 철공진(鐵共振) 제어대책(制御對策)에 관한 연구(硏究))

  • Kim, S.K.;Kim, T.S.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.05b
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    • pp.216-221
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    • 2000
  • This paper describes the analysis results on the PT ferroresonance at 154 kV GIS (gas Insulated substation by EMTP(Electro- magnetic Transient Program). We had simulated the PT ferroresonance between a potential transformer(PT) and an open circuit breaker's grading capacitance. The ferroresonance leads to very large power frequency overvoltages on PT bus and subsequent insulation failure. The large power can be supplied to the PT by the high voltage on the opened circuit due to the grading capacitance and equivalent capacitance of the buses during the ferroresonance. The damping circuit connected on the secondary winding were considered in the model. The actual countermeasure include a saturable inductor and a resistor series-mounted, but the 2 ohms of damping resistance was used in the computationl model.

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Operation Analysis of th Watkins-Johnson Converter (Watkins-Johnson 컨버터의 동작특성 해석)

  • 안태영
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.34S no.6
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    • pp.85-93
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    • 1997
  • This paper analyzes the steady-state and dynamic characteristics of the watkings-johnson converter. the major contributions of this paper includ identification of the following characteristics unique to the watkins-johnson converter: (1) The output voltage of the converter is nearly constant at the continous conduction mode (CCM), and at discontinousou conduction mode (DCM) it decreses linerly as the output curretn increases. (2) The control-to-output transfer function is a second-order one with a left-half-plane (LHP) zero determined by the combination of the output capacitor and equivalent series resistor of the converter. This LHP zero signinificantly improves the stability of the converter. (3) The control-to-output transfer function reduces to a first-order one, as the converter moves from CCM to DCM. (4) The parastic resistance of the inductor does not cause any significant influence on poles and zeros of the transfer function.

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Boost Converter Modeling of Photovoltaic System Using PWM Switch Model (PWM 스윗치 모델을 이용한 PV용 Boost Converter Modelling)

  • Kim, H.J.;Lee, K.O.;Choi, J.Y.;Jung, Y.S.;Yu, G.J.;Kwon, J.D.
    • Proceedings of the KIEE Conference
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    • 2002.11d
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    • pp.286-293
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    • 2002
  • Photovoltaic systems normally use a maximum power point tracking (MPPT) technique to continuously deliver the highest possible power to the load when variations in the insolation and temperature occur. A simple method of tracking the maximum power points (MPPs) and forcing the boost converter system to operate close to these Points is presented through deriving small-signal model and transfer function of boost converter. This paper aims at modeling boost converter including equivalent series resistance of input reservoir capacitor by state-space-averaging method and PWM switch model. In the future, properly designed controller for compensation will be constructed in real system for maximum photovoltaic power tracking control.

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Life Estimation of Electrolytic Capacitors for Inverters (인버터용 전해커패시터의 수명 추정)

  • Lee, Dong-Choon;Kim, Hyung-Jin
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.50 no.7
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    • pp.338-346
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    • 2001
  • In this paper, dc link currents for the three-phase diode rectifiers and PWM inverters are analyzed and an algorithm of estimating the life of dc link electrolytic capacitors using the analyzed ripple current is presented. Since the capacitor life is dependent on the operating temperature, the power dissipation in capacitors should be calculated. For this, the ESR(equivalent series resistance) model of the capacitor is derived and ripple currents through the capacitor are analyzed. Relating the power dissipation and the heat transfer equation, the internal operating temperature is calculated. Then, the capacitor life can be predicted by using Arrhenius's equation. An example for applications is given for the practical system.

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A analysis result on the PT ferroresonance at 154 kV GIS substation (154 kV GIS의 PT 철공진 소손사례와 원인규명)

  • Woo, J.W.;Shim, E.B.;Kim, S.K.
    • Proceedings of the KIEE Conference
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    • 1999.07e
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    • pp.2076-2079
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    • 1999
  • This paper describes the analysis results on the PT ferroresonance at 154 kV GIS (gas Insulated substation by EMTP (Electro-magnetic Transient Program). We had simulated the PT ferroresonance between a potential transformer(PT) and an open circuit breaker's grading capacitance. The ferroresonance leads to very large power frequency overvoltages on PT bus and subsequent insulation failure. The large power can be supplied to the PT by the high voltage on the opened circuit due to the grading capacitance and equivalent capacitance of the buses during the ferroresonance. The damping circuit connected on the secondary winding were considered in the model. The actual countermeasure include a saturable inductor and a resistor series-mounted, but the 2 ohms of damping resistance was used in the computational model.

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Failure Prediction Monitoring of DC Electrolytic Capacitors in Half-bridge Boost Converter (단상 하프-브리지 부스트 컨버터에서 DC 전해 커패시터의 고장예측 모니터링)

  • Seo, Jang-Soo;Shon, Jin-Geun;Jeon, Hee-Jong
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.63 no.4
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    • pp.345-350
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    • 2014
  • DC electrolytic capacitor is widely used in the power converter including PWM inverter, switching power supply and PFC Boost converter system because of its large capacitance, small size and low cost. In this paper, basic characteristics of DC electrolytic capacitor vs. frequency is presented and the real-time estimation scheme of ESR and capacitance based on the bandpass filtering is adopted to the single phase boost converter of uninterruptible power supply to diagnose its split dc-link capacitors. The feasibility of this real-time failure prediction monitoring system is verified by the computer simulation of the 5[kW] singe phase PFC half-bridge boost converter.

A Study on Implementation of Active Power Decoupling Circuit for Boost Type PFC Rectifier with Low DC Link Capacitance (낮은 직류 링크 커패시턴스를 갖는 승압형 PFC 정류기를 위한 Active Power Decoupling 회로 구현에 관한 연구)

  • Hwang, Deok-hwan;Lee, Jungyong;Cho, Younghoon;Choe, Gyu-ha
    • Proceedings of the KIPE Conference
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    • 2017.07a
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    • pp.246-247
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    • 2017
  • 단상 ac/dc, dc/ac 시스템의 경우, ac와 dc사이의 전력 불균형으로 인해 double line frequency ripple power가 발생한다. 이는 harmonic disturbance을 야기시킨다. 일반적으로 전력 리플을 줄이기 위하여 dc-link에 용량이 큰 전해 커패시터를 사용하는데, 용량이 큰 전해 커패시터는 높은 equivalent series resistance(ESR)을 가지며, 상대적으로 짧은 수명을 갖는 한계를 갖는다. 본 논문은 active power decoupling을 추가함으로써 전해 커패시터를 용량이 작은 필름 커패시터로 대체한 회로 구조를 제시한다. 그리고 dc-link 커패시터 선정방법, 설계한 제어기의 성능과 부하 변동에 따른 실험을 PSIM 시뮬레이션으로 확인하고 실험을 통해 검증한다.

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Single-phase Trans-Z-Source AC-AC Converter (단상 트랜스-Z-소스 AC-AC 컨버터)

  • Shin, Hyunhak;Chae, Junyoung;Joung, Minjae
    • Proceedings of the KIPE Conference
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    • 2015.07a
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    • pp.407-408
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    • 2015
  • The existing (q)Z-source PWM AC-AC converters have limited voltage gain because of the equivalent series resistance in the Z-source inductor. In order to obtain higher voltage gain than (q)Z-source AC-AC converters, a coupled inductor (or transformer) based Z-source AC-AC converter is proposed in this paper. By increasing turns ratio of the coupled inductor more than 1, the proposed converter can obtain higher output voltage than (q)Z-source converters with the same duty ratio. A 120 W prototype AC-AC converter is built and tested to verify performances of the proposed converter.

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The study on DC-link Film Capacitor in 3 Phase Inverter System for the Consideration of Frequency Response (3상 인버터 시스템에서 주파수 특성을 고려한 필름 콘덴서의 DC-link 적용 방법에 관한 연구)

  • Park, Hyun-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.4
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    • pp.117-122
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    • 2018
  • A large-capacity three-phase system air conditioner recently includes an inverter circuit to reduce power consumption. The inverter circuit uses a DC voltage that comes from DC-link power capacitor with the function of rectifying, which means AC voltage to DC voltage using a diode. An electrolytic capacitor is generally used to satisfy the voltage ripple and current ripple conditions of a DC-link power capacitor used for rectifying. Reducing the capacitance of the capacitor decreases the size, weight, and cost of the circuit. This paper proposes an algorithm to reduce the input ripple current by combining the minimum point estimation phase locked loop (PLL) phase control and the average voltage d axis current control technique. When this algorithm was used, the input ripple current decreased by almost 90%. The current ripple of the DC-link capacitor decreased due to the decrease in input ripple current. The capacitor capacity can be reduced but the electrolytic capacitor has a heat generation problem and life-time limitations because of its large equivalent series resistance (ESR). This paper proposes a method to select a film capacitor considering the current ripple at DC-link stage instead of an electrolytic capacitor. The capacitance was selected considering the voltage limitation, RMS (Root Mean Square) current capacity, and RMS current frequency analysis. A $1680{\mu}F$ electrolytic capacitor can be reduced to a $20{\mu}F$ film capacitor, which has the benefit of size, weight and cost. These results were verified by motor operation.

Frequency Characteristics of Anodic Oxide Films: Effects of Anodization Valtage

  • Lee, Dong-Nyung;Yoon, Young-Ku
    • Nuclear Engineering and Technology
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    • v.6 no.1
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    • pp.14-22
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    • 1974
  • Effects of anodization voltage on frequency characteristics of anodic oxide films on tantalum were analyzed based on the following impedance equatious : (equation omitted) Here $R_{f}$, $C_{f}$ and tan $\delta$$_{f}$ are equivalent series resistance in ohm, equivalent Belies capacitance in farad and dielectric loss, of anodic oxide films respectively Parameters P, $\tau$$_{ο}$, $\tau$$_{\omega}$, and Co are defined as follows: P=(d-w)/w, $\tau$$_{ο}$=$textsc{k}$$\rho$$_{ο}$, $\tau$$_{\omega}$=$textsc{k}$$\rho$$_{\omega}$, $C_{ο}$=$textsc{k}$A/d where d is the thickness of oxide film, $\omega$ is the diffusion layer thickness. $\rho$$_{ο}$ is the resistivity of oxide film at the interface of metal and the oxide, $\rho$$_{\omega}$ is the resistivity of oxide film at intrinsic region and A is the area of the film and $textsc{k}$=0.0885$\times$10$^{-12}$ $\times$dielectric constant, (in farad/cm). It was shown that dielectric loss and frequency dependence of equivalent series capacitance decrease as anodization voltage increases. This is a consequence of the fact that the thickness of diffusion layer increases a little with increasing anodization voltage whereas the total oxide thickness is proportional to the anodization voltage. The ngative deviation of measured values from tile relation, tan $\delta$$_{f}$=0.682 $\Delta$ $C_{f}$, was also discussed based on the Impedance equations given above. Here $\Delta$ $C_{f}$ is the change in capacitance between 0.1 and 1 KHZ.KHZ.Z.

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