• Title/Summary/Keyword: ESR estimation

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Estimation of ESR in the DC-Link Capacitors of AC Motor Drive Systems with a Front-End Diode Rectifier

  • Nguyen, Thanh Hai;Le, Quoc Anh;Lee, Dong-Choon
    • Journal of Power Electronics
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    • v.15 no.2
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    • pp.411-418
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    • 2015
  • In this paper, a new method for the online estimation of equivalent series resistances (ESR) of the DC-link capacitors in induction machine (IM) drive systems with a front-end diode rectifier is proposed, where the ESR estimation is conducted during the regenerative operating mode of the induction machine. In the first place, a regulated AC current component is injected into the q-axis current component of the induction machine, which induces the current and voltage ripple components in the DC-link. By processing these AC signals through digital filters, the ESR can be estimated by a recursive least squares (RLS) algorithm. To acquire the AC voltage across the ESR, the DC-link voltage needs to be measured at a double sampling frequency. In addition, the ESR current is simply reconstructed from the stator currents and switching states of the inverter. Experimental results have shown that the estimation error of the ESR is about 1.2%, which is quite acceptable for condition monitoring of the capacitor.

An Improvement On-Line Failure Diagnosis of DC Link Capacitor in PWM Power Converters (PWM 전력 컨버터에서 DC 링크 커패시터의 개선된 온라인 고장 진단)

  • Shon, Jin-Geun;Na, Chae-Dong
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.59 no.1
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    • pp.40-46
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    • 2010
  • DC link electrolytic capacitors are widely used in various PWM power converter system, such as adjustable speed driver(ASD) or DC/DC converter. Electrolytic capacitors, which is the most of the time affected by aging effect, plays a very important role for the power electronics system quality and reliability. This objective of this paper is to propose a improvement method to detect the rise of equivalent series resistor(ESR) in order to realize the online failure prediction of electrolytic capacitor for DC link of PWM power converter. The ESR detection scheme is based on the determination of the electrolytic capacitor AC losses calculated from voltage/current measurement using AC coupling. Therefore, the preposed online failure prediction method has the merits of easy ESR computation and circuit simplicity compare with BPF method. Simulation results show the veridity of the proposed on-line ESR estimation method.

Life Estimation of DC Link Electroytic Capacitors (직류 링크 전해 커패시터의 수명 추정)

  • 이동춘
    • Proceedings of the KIPE Conference
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    • 2000.07a
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    • pp.57-60
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    • 2000
  • An aluminum electrolytic capacitor is used in DC Link of ac motor drive system. In this case it usually has the shortest lifetime in the system and then determines the system lifetime. Therefore life estimation of the electrolytic capacitor is needed for maintenance of th circuit. In this paper a method for life estimation is presented with a ESR(equivalent series resistance) model and a heat transfer model of capacitor that can be used to estimate operating temperature it is investigated through a simple example using ESR and heat transfer.

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A Simple ESR Measurement Method for DC Bus Capacitor Using DC/DC Converter (DC/DC 컨버터를 이용한 DC Bus 커패시터의 간단한 ESR 측정 기법)

  • Shon, Jin-Geun;Kim, Jin-Sik
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.59 no.4
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    • pp.372-376
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    • 2010
  • Electrolytic capacitors have been widely used in power electronics system because of the features of large capacitance, small size, high-voltage, and low-cost. Electrolytic capacitors, which is most of the time affected by aging effect, plays a very important role for the power electronics system quality and reliability. Therefore it is important to estimate the parameter of an electrolytic capacitor to predict the failure. The estimation of the equivalent series resistance(ESR) is important parameter in life condition monitoring of electrolytic capacitor. This paper proposes a simple technique to measure the ESR of an electrolytic capacitor. This method uses a switching DC/DC boost converter to measure the DC Bus capacitor ESR of power converter. Main advantage of the proposed method is very simple in technique, consumes very little time and requires only simple instruments. Simulation results are shown to verify the performance of the proposed method.

Detection and Absorbed-Dose Estimation of Electron Beam-Irradiated Dried Vegetable Using ESR Spectroscopy (ESR Spectroscopy에 의한 전자선 조사 건조 채소의 검지와 흡수선량 예측)

  • 권중호;정형욱
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.28 no.4
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    • pp.882-885
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    • 1999
  • Along with the increasing demands for food irradiation technology, proper detection methods for controlling irradiated foods are required. Dried vegetable(chunggyungchae), which is permitted to be irradiated in Korea, was subjected to a detection study by ESR spectroscopy. Pre established threshold value was successfully applicable to the detection of 50 coded unknown samples of dried clean vege tables, both nonirradiated and electron beam irradiated. Three calibration curves obtained from the samples irradiated at 2.5~15 kGy were not practically adopted to estimate actual absorbed doses ranging from 4 to 7 kGy.

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Characteristic Investigation of External Parameters for Fault Diagnosis Reference Model Input of DC Electrolytic Capacitor (DC 전해 커패시터의 고장진단 기준모델 입력을 위한 외부변수의 특성 고찰)

  • Park, Jong-Chan;Shon, Jin-Geun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.61 no.4
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    • pp.186-191
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    • 2012
  • DC Bus Electrolytic capacitors have been widely used in power conversion system because they can achieve high capacitance and voltage ratings with volumetric efficiency and low cost. This type of capacitors have been traditionally used for filtering, voltage smoothing, by-pass and other many applications in power conversion circuits requiring a cost effective and volumetric efficiency components. Unfortunately, electrolytic capacitors are some of the weakest components in power electronic converter. Many papers have proposed different methods or algorithms to determinate the ESR and/or capacitance C for fault diagnosis of the electrolytic capacitor. However, both ESR and C vary with frequency and temperature. Accurate knowledge of both values at the capacitors operating conditions is essential to achieve the best reference data of fault judgement. According to parameter analysis, the capacitance increases with temperature and the ESR decreases. Higher frequencies make the ESR and C to decrease. Analysis results show that the proposed electrolytic capacitor parameter estimation technique can be applied to reference signal of capacitor diagnosis systems successfully.

Menopausal Status Modifies Breast Cancer Risk Associated with ESR1 PvuII and XbaI Polymorphisms in Asian Women: a HuGE Review and Meta-analysis

  • Li, Li-Wen;Xu, Lei
    • Asian Pacific Journal of Cancer Prevention
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    • v.13 no.10
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    • pp.5105-5111
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    • 2012
  • Background: Published data on the association between single nucleotide polymorphisms (SNPs) in the ESR1 gene and breast cancer susceptibility are inconclusive or controversial. The aim of this Human Genome Epidemiology (HuGE) review and meta-analysis was to derive a more precise estimation of this relationship. Methods: A literature search of Pubmed, Embase, Web of science and CBM databases was conducted from inception through September 1th, 2012. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. Results: A total of five studies including 1,678 breast cancer cases and 1,678 general population controls in Asian populations were involved in this meta-analysis. When all the eligible studies were pooled into the meta-analysis, the higher transcriptional activity variant allele T of ESR1 PvuII (C>T) (rs2234693) in pre-menopausal breast cancer women showed a significant relation to increased risk (OR = 1.13, 95%CI: 1.01-1.28, P = 0.040) in contrast to their post-menopausal counterparts which showed non-significant increased risk (OR = 1.01, 95%CI: 0.87-1.18, P = 0.858). Nevertheless, no significant association between ESR1 XbaI (A>G) (rs9340799) polymorphism and the risk of breast cancer was observed in pre-menopausal and post-menopausal individuals. Conclusion: Based on a homogeneous Asian population, results from the current meta-analysis indicates that the ESR1 PvuII (C>T) polymorphism places pre-menopausal breast cancer women at risk for breast cancer, while ESR1 XbaI (A>G) polymorphism is not likely to predict the risk of breast cancer.

THE CHANGES OF SERUM C-REACTIVE PROTEIN IN THE HEAD AND NECK INFECTION (두경부 감염 환자에서 혈청 내 C-Reactive Protein의 변화)

  • Lee, Ju-Hyun;Kim, Chin-Soo;Lee, Sang-Han;Kim, Chul-Hwan
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.29 no.1
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    • pp.5-13
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    • 2003
  • The purpose of this study is to determine the value of serum concentration of C-reactive protein(CRP) in comparison with ESR and leukocyte as the tools for diagnosis and follow-up study of infection. For this study, thirty-one patients with head and neck infection and thirty-two patients performed the orthognathic surgery were selected for experimental and control groups each other. we analyzed the blood sample daily to measure CRP, ESR and leukocytosis. The results of this study are as the following : 1. Serum C-Reactive Protein levels in the experimental group were higher than control group and the pattern of CRP changes continued to decline in both groups(P<0.001). 2. ESR changes in both groups were scattered without any special pattern. 3. Correlation between CRP and Leukocyte was higher than others(r=0.664, P<0.01). 4. In the Receiver Operating Characteristic(ROC) Curve of experimental group, rapid increase of CRP curve and Area under the curve(AUC) value, 0.774, indicate the high accuracy of estimation. 5. In experimental group, sensitivity of CRP, ESR, and Leukocytosis on recovery day were 83%, 17% and 71%. Based on the results of this study, we could conclude that determination of CRP is more useful method to diagnosis and follow-up study of infection than other commonly used variables in oral and maxillofacial region.

Life Estimation of Electrolytic Capacitors in Inverters (인버터용 전해커페시터의 수명 추정)

  • Lee, Dong-Choon
    • Proceedings of the KIEE Conference
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    • 2000.11a
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    • pp.243-245
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    • 2000
  • In general, aluminum electrolytic capacitors are used in the DC link of PWM inverters fur ac motor drives. The capacitor usually has the shortest lifetime in the system and then determines the lifetime of the inverter system. In this paper, a method of capacitor lifetime estimation is proposed by using an ESR(equivalent series resistance) model and a heat transfer model of capacitor, from which internal operating temperature is estimated. Then, the lifetime is predicted by Arrhenius's equation. A practical example is presented.

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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.