• Title/Summary/Keyword: equivalent series resistance

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A development of Diagnosis Monitoring System for UPS DC Link Capacitors using Zigbee Wireless Communication (Zigbee 무선통신을 이용한 UPS DC링크 커패시터의 고장 모니터링 시스템 개발)

  • Kim, Dong-Jun;Shon, Jin-Geun;Jeon, Hee-Jong
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.61 no.1
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    • pp.41-46
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    • 2012
  • Electrolytic power capacitors have been widely used in power conversion system such as inverter or UPS because of characteristics of large capacitance, high-voltage and low-cost. The electrolytic capacitor, which is most of the time affected by the aging effect, plays a very important role for the power-electronics system quality and reliability. Therefore it is important to diagnosis monitoring the condition of an electrolytic capacitor in real-time to predict the failure. In this paper, the on-line remote diagnosis monitoring system for UPS DC link electrolytic capacitors using low-cost single-chip zigbee communication modules is developed. To estimate the health status of the capacitor, the equivalent series resistor(ESR) of the component has to be determined. The capacitor ESR is estimated by using RMS computation using BPF modeling of DC link ripple voltage/current. Zigbee-based hardware experimental results show that the proposed remote capacitor diagnosis monitoring system can be applied to UPS successfully.

Examination of the Cause of Damage to Capacitors for Home Appliances and Analysis of the Heat Generation Mechanism (가전용 커패시터의 소손원인 규명 및 발열 메커니즘 해석)

  • Park, Hyung-Ki;Choi, Chung-Seog
    • Journal of the Korean Society of Safety
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    • v.26 no.6
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    • pp.13-19
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    • 2011
  • The purpose of this study is to examine the cause of damage to electrolytic capacitors and to present the heat generation mechanism in order to prevent the occurrence of similar problems. From the analysis results of electrolytic capacitors collected from accident sites, the fire causing area can be limited to the primary power supply for the initial accident. From the tests performed by applying overvoltage, surge, etc., it is thought that the fuse, varistor, etc., are not directly related to the accidents that occurred. The analysis of the characteristics using a switching regulator showed that the charge and discharge characteristics fell short of standard values. In addition, it is thought that heated electrolytic capacitors caused thermal stress to nearby resistances, elements, etc. It can be seen that the heat generation is governed by the over-ripple current, application of AC overvoltage, surge input, internal temperature increase, defective airtightness, etc. Therefore, when designing an electrolytic capacitor, it is necessary to comprehensively consider the correct polarity arrangement, appropriate voltage application, correct connection of equivalent series resistance(ESR) and equivalent series inductance(SEL), rapid charge and discharge control, sufficient margin of dielectric tangent, etc.

On-line Remote Diagnosis System for DC Bus Capacitor of Power Converters Using Zigbee Communication (Zigbee통신을 이용한 전력변환기기의 DC Bus 커패시터의 온라인 원격 고장진단 시스템)

  • Chung, Wan-Sup;Shon, Jin-Geun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.64 no.1
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    • pp.29-34
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    • 2015
  • DC bus electrolytic capacitors are used in variety of equipments as smoothing element of the power converters because it has high capacitance for its size and low price. It is responsible for frequent breakdowns of many static converters and inverter drive systems. Therefore it is important to diagnosis monitoring the condition of an electrolytic capacitor in real-time to predict the failure of power converter. In this paper, the on-line remote diagnosis monitoring system for DC BUS electrolytic capacitors of power converter using low-cost type Zigbee communication modules is developed. To estimate the health status of the capacitor, the equivalent series resistor(ESR) of the component has to be determined. The capacitor ESR is estimated by using RMS computation using AC coupling method of DC link ripple voltage/current. The Zigbee communication-based experimental results show that the proposed remote DC capacitor diagnosis monitoring system can be applied to DC/DC converter and UPS successfully.

Design of Wideband Thin Absorber Using Resistive Cross-Shaped Surface Structures (저항성 십자 표면 구조를 이용한 광대역 박형 흡수체 설계)

  • Lee, Jun-Ho;Kim, Gunyoung;Lee, Bom-Son
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.26 no.3
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    • pp.311-316
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    • 2015
  • This paper presents a design method for thin but wideband absorbers using resistive sheets. Its equivalent circuit consists of a series RLC resonant circuit and a short-terminated transmission line. Based on this equivalent circuit, we presented the three conditions for an electromagnetic absorber which has a thickness less than a quarter wavelength and wide absorption bandwidth at center frequency. By using an root-finding algorithm, the equivalent resistance, capacitance, and inductance of the absorbers are obtained. These equivalent circuit values for the absorber surface can be realized by a 2D periodic cross-shaped structure which has required surface resistance. Using the design method, we have designed the absorber which has 18.75 mm($67.5^{\circ}$ electrical length) thickness and 90 % absorption bandwidth of 116 % bandwidth at 3 GHz.

Transient Analysis of Magnetodynamic Systems Using Frequency-dependent Circuit Parameters (주파수 의존적인 회로상수를 이용한 시변자장 시스템의 과도상태 해석)

  • Choi, Myung-Jun;Lee, Se-Hee;Park, Il-Han
    • Proceedings of the KIEE Conference
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    • 1999.07a
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    • pp.61-63
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    • 1999
  • This paper presents an efficient method for analysis of magnetodynamic system using frequency-dependent parameters. In equivalent electric circuit of linear magnetodynamic system, parameters of inductance and resistance are not constant since they vary with its driving frequency. Once frequency-dependent parameters of equivalent electric circuit for a given system are extracted, they can be used to analyze various characteristics of system. We use the Fourier transform, the high-order sensitivity method and Taylor series in order to efficiently extract the frequency-dependent parameters of magnetodynamic system. The proposed algorithm is applied to an induction heating system to validate its numerical efficiency.

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Improvement of Electrochemical Characteristics by Changing Morphologies of Carbon Electrode (탄소 전극 형상 변화에 따른 전기화학 커패시터 특성 향상)

  • Min, Hyung-Seob;Kim, Sang-Sig;Cheong, Deock-Soo;Choi, Won-Kook;Oh, Young-Jei;Lee, Jeon-Kook
    • Korean Journal of Materials Research
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    • v.19 no.10
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    • pp.544-549
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    • 2009
  • Activated carbon (AC) with very large surface area has high capacitance per weight. However, such activation methods tend to suffer from low yields, below 50%, and are low in electrode density and capacitance per volume. Carbon NanoFibers (CNFs) had high surface area polarizability, high electrical conductivity and chemical stability, as well as extremely high mechanical strength and modulus, which make them an important material for electrochemical capacitors. The electrochemical properties of immobilized CNF electrodes were studied for use as in electrical double layer capacitor (EDLC) applications. Immobilized CNFs on Ni foam grown by thermal chemical vapor deposition (CVD) were successfully fabricated. CNFs had a uniform diameter range from 50 to 60 nm. Surface area was 56 m$^2$/g. CNF electrodes were compared with AC and multi wall carbon nanotube (MWNT) electrodes. The electrochemical performance of the various electrodes was examined with aqueous electrolyte of 2M KOH. Equivalent series resistance (ESR) of the CNF electrodes was lower than that of AC and MWNT electrodes. The specific capacitance of 47.5 F/g of the CNF electrodes was achieved with discharge current density of 1 mA/cm$^2$.

Transistor Wide-Band Feedback Amplifiers (트랜지스터 광대역궤환증폭기)

  • 이병선;이상배
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.5 no.1
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    • pp.13-25
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    • 1968
  • A detailed analysis of the transistor wide-band feedback amplifiers using the hybrid-$\pi$ equivalent circuit has been made. It is considered both for the low freqnency and for the high frequency. The expressions of the gain, bandwidth. input impedance and output impedance have been presented. It is shown that a series feedback amplifier should be driven from the voltage source and should drive into the low resistance load, and a shunt feedback amplifier should be driven from the current source and should drive into the high resistance load. It is also shown that these stages can be coupled without use of the buffer stage or coupling transformer.

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Electrochemical Characteristics of Activated Carbon Electrode for Supercapacitor (Supercapacitor용 활성탄 전극의 전기 화학적 특성)

  • 김경민;이용욱;강안수
    • Proceedings of the Safety Management and Science Conference
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    • 2002.11a
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    • pp.273-277
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    • 2002
  • In the electrode fabrication of unit cell, we found that optimal the electrochemical characteristics were obtained with at 90 wt.% of activated carbon(BP-20), 5 wt.% of conducting agent(Ppy, Super P) and 5 wt.% of P(VdF-co-HFP)/PVP mixed binder. The electrochemical characteristics of unit cell with Ppy improver were as follows : 37.6 F/g of specific capacitance, 0.98 $\Omega$ of AC-ESR, 2.92 Wh/kg and 6.05 Wh/L of energy density, and 754 W/kg and 1,562 W/L of power density. It was confirmed that internal resistance were reduced due to the increase of electrical conductivity and filling density by the introduction of conductivity agent, and content of conducting agent was suitable in the range of 4~6 wt.%. According to the impedance measurement of the electrode with conductivity agent, we found that it was possible to charge rapidly by the fast steady-state current convergence due to low equivalent series resistance(AC-ESR), fast charge transfer rate at interface between electrode and electrolyte, and low RC time constant.

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Electrochemical Impedance Analysis of Polyaniline-Film on Tungsten Electrodes (텅스텐 전극에 입힌 폴리아닐린의 전기화학적 임피던스)

  • Chon, Jung-Kyoon;Min, Byoung Hoon
    • Journal of the Korean Chemical Society
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    • v.40 no.1
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    • pp.37-43
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    • 1996
  • The electrochemical impedance spectra of polyaniline film coated on tungsten electrodes by cyclic voltammetry have been measured in 0.1 M aqueous sulfuric acid solution. An electrochemical cell composed of large redox capacitance and low resistance of PANI-film in series was in agreement with the conductive behavior reported at these potentials. When the PANI was coated on bare tungsten, the electrolytic resistance was only observed. However, on the oxidized tungsten instead of bare tungsten, the resistance of tungsten oxide and the contact resistance between PANI and tungsten oxide were additionally observed. Equivalent electrical circuits have been deduced from the impedance data. It was therfore possible to obtain the parameters of the ionic mass transport within the film.

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A simple approach for quality evaluation of non-slender, cast-in-place piles

  • Zhang, Ray Ruichong
    • Smart Structures and Systems
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    • v.4 no.1
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    • pp.1-17
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    • 2008
  • This study proposes a conceptual framework of in-situ vibration tests and analyses for quality appraisal of non-slender, cast-in-place piles with irregular cross-section configuration. It evaluates a frequency index from vibration recordings to a series of impulse loadings that is related to total soil-resistance forces around a pile, so as to assess if the pile achieves the design requirement in terms of bearing capacity. In particular, in-situ pile-vibration tests in sequential are carried out, in which dropping a weight from different heights generates series impulse loadings with low-to-high amplitudes. The high-amplitude impulse is designed in way that the load will generate equivalent static load that is equal to or larger than the designed bearing capacity of the pile. This study then uses empirical mode decomposition and Hilbert spectral analysis for processing the nonstationary, short-period recordings, so as to single out with accuracy the frequency index. Comparison of the frequency indices identified from the recordings to the series loadings with the design-based one would tell if the total soil resistance force remains linear or nonlinear and subsequently for the quality appraisal of the pile. As an example, this study investigates six data sets collected from the in-situ tests of two piles in Taipu water pump project, Jiangshu Province of China. It concludes that the two piles have the actual axial load capacity higher than the designed bearing capacity. The true bearing capacity of the piles under investigation can be estimated with accuracy if the amplitude of impact loadings is further increased and the analyses are calibrated with the static testing results.