• Title, Summary, Keyword: Impedance network

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Impedance Analysis of High Integrated Sensor Array Using Impedance Relation Matrix (임피던스 관계 행렬을 이용한 고집적 센서 어레이의 임피던스 분석에 관한 연구)

  • Lee, Hak-Sung
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.48 no.3
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    • pp.1-5
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    • 2011
  • In order to analyze the impedance properties of high integrated impedance network with multiple terminals, this paper introduces the concept of impedance relation matrix(IRM). The linear relation between the terminal voltages and currents is represented in the form of IRM and this matrix can be utilized to calculate the impedance between any two terminals. Furthermore, IRM representation for 2-port impedance network can be also defined. The whole impedance network is divided into the several 2-port sub-networks and each sub-network is analyzed in a form of the IRM representation. An illustrated example is given to show that the proposed method is simple and effective to analyze the impedance of a sensor array which has a very large number of impedance elements.

Impedance measurement and analysis of overhead medium voltage power lines for broad band power line communication (BPLC) ($1{\sim}30MHz$ 광대역 전력선 통신을 위한 고압 배전선의 임피던스 특성 측정 및 해석)

  • Park, Young-Jin;Lee, Jae-Jo;Kim, Kwan-Ho;Lee, Won-Tae
    • Proceedings of the KIEE Conference
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    • pp.2345-2347
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    • 2005
  • In this paper, impedance characteristics of overhead medium-voltage (MV) power lines is reported for power line communication (PLC) over an MV power line network. For analysis, a two-port equivalent network model of MV power lines is derived. By applying the transmission line theory, reflection behavior and impedance of power lines are investigated. For verification, impedance of power lines is measured at a test field for an MV PLC. The results show that impedance of MV power lines is between $200{\Omega}$ and $300{\Omega}$ and converges to a half of their characteristic impedance.

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Method for Adjusting Single Matching Network for High-Power Transfer Efficiency of Wireless Power Transfer System

  • Seo, Dong-Wook;Lee, Jae-Ho;Lee, Hyungsoo
    • ETRI Journal
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    • v.38 no.5
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    • pp.962-971
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    • 2016
  • A wireless power transfer (WPT) system is generally designed with the optimum source and load impedance in order to achieve the maximum power transfer efficiency (PTE) at a specific coupling coefficient. Empirically or intuitively, however, it is well known that a high PTE can be attained by adjusting either the source or load impedance. In this paper, we estimate the maximum achievable PTE of WPT systems with the given load impedance, and propose the condition of source impedance for the maximum PTE. This condition can be reciprocally applied to the load impedance of a WPT system with the given source impedance. First, we review the transducer power gain of a two-port network as the PTE of the WPT system. Next, we derive two candidate conditions, the critical coupling and the optimum conditions, from the transducer power gain. Finally, we compare the two conditions carefully, and the results therefore indicate that the optimum condition is more suitable for a highly efficient WPT system with a given load impedance.

Impedance-Matching Network Box of the RF Power Amplifier for the RFT-30 Cyclotron

  • Song, Ho Seung;Kong, Young Bae;Lee, Eun Je;Hur, Min Goo
    • Journal of the Korean Physical Society
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    • v.73 no.8
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    • pp.1186-1190
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    • 2018
  • RFT-30 is a 30-MeV prototype cyclotron for radioactive isotope (RI) production, neutron generation, and fundamental research. Charged particles are accelerated by using a radio-frequency (RF) cavity and a high-power RF signal transmitted by an RF amplifier. This paper describes the impedance-matching network box of an RF power amplifier for an RFT-30 cyclotron. The impedance-matching process is an essential procedure for maximizing the RF amplifier's performance with respect to efficiency and stability. In a dummy load test, the impedance value remains almost constant. However, in terms of beam loading, the impedance varies because of the vacuum and water/air cooling. These effects make the resonance conditions different; thus, the RF amplifier's operation becomes unstable. In this work, an impedance-matching network box with a stub-line inductor, which is applied to the cathode of the power amplifier (PA) tube, is proposed. A calculation for the impedance-matching network box was performed and then simulated through optimization processes. In addition, the stub-line inductor measurement and the RF performance when using this matching network box are described.

A Study on the Detection of LIF and HIF Using Neural Network (신경회로망을 이용한 LIF 및 HIF검출에 판한 연구)

  • Choi, H.S.;Park, S.W.;Chae, J.B.;Kim, C.H.
    • Proceedings of the KIEE Conference
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    • pp.924-926
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    • 1997
  • A high impedance fault(HIF) in a power system could be due to a downed conductor, and is a dangerous situation because the current may be too small to be detected by conventional means. In this paper, HIF(High impedance fault) and LIF(Low impedance fault) detection methods were reviewed. No single defection method can detect all electrical conditions resulting from downed conductor faults, because high impedance fault have arc phenomena, asymmetry and randomness. Neural network are well-suited for solving difficult signal processing and pattern recognition problem. This paper presents the application of artificial neural network(ANN) to detect the HIF and LIF. Test results show that the neural network was able to identify the high impedance fault by real-time operation. Furthermore, neural network was able to discriminate the HIF from the LIF.

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Bandwidth Enhancement for a Proximity Coupled Microstrip patch Antenna with an Impedance Matching Network (임피던스 정합기를 이용한 근접 결합 급전 패치 안테나의 대역폭 확장)

  • Kwak, Eun-Hyuk;Kim, Boo-Gyoun
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.2
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    • pp.55-69
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    • 2015
  • Bandwidth enhancement technique for a proximity coupled patch antenna is investigated. The bandwidth and radiation characteristics of a proximity coupled patch antenna with an integrated impedance matching network printed on substrates with various dielectric constants and thicknesses are compared to those of a proximity coupled patch antenna without an impedance matching network. The bandwidth of a proximity coupled patch antenna with an integrated impedance matching network is greatly increased than that of a proximity coupled patch antenna without an impedance matching network without the degradation of radiation characteristics.

Estimation of Equivalent Circuit Parameters of Underwater Acoustic Piezoelectric Transducer for Matching Network Design of Sonar Transmitter (소나 송신기의 정합회로 설계를 위한 수중 음향 압전 트랜스듀서의 등가회로 파라미터 추정)

  • Lee, Jeong-Min;Lee, Byung-Hwa;Baek, Kwang-Ryul
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.3
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    • pp.282-289
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    • 2009
  • This paper presents an estimation technique of the equivalent circuit parameters for an underwater acoustic piezoelectric transducer from the measured impedance. Estimated equivalent circuit can be used for the design of the impedance matching network of the sonar transmitter. A fitness function is proposed to minimize the error between the calculated impedance of the equivalent circuit and the measured impedance of the transducer. The equivalent circuit parameters are estimated by using the fitness function and the PSO(Particle Swarm Optimization) algorithm. The effectiveness of the proposed method is verified by the applications to a sandwich-type transducer and a dummy load. In addition, the impedance matching network is also designed by using the estimated equivalent circuit model.

Impedance Measurement and Matching Technique for Medium-Voltage Powerline Communication (고압전력선 통신을 위한 임피던스 측정 및 정합 방안 연구)

  • 이재조;유정훈;홍충선;이대영
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.53 no.5
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    • pp.345-352
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    • 2004
  • Currently, high data rate PLC(Power Line Communications), up to 100 Mbps, which use frequency bandwidth between 2 MHz and 30 MHz is investigated very hard, and commercial PLC modem for low voltage powerline network (indoor) is coming soon into communication market. For the purpose of developing a fit communication system which has little distortion of signal and attenuation, it is surely necessary to know about channel environments of powerline. Especially, the impedance measurement of the powerline and impedance matching are very important. As is known, since medium-voltage powerline (22.9 ㎸) is still working, it is not so simple to measure the powerline impedance. In our study, a portable impedance measurement equipment is developed. It consists of coupling capacitor, a drain coil and impedance matching transformer. The equipment is easily connected to medium voltage line and impedance of power line is measured using a network analyzer. Also, measurement results are used for impedance matching of PLC signal. In fact, matching transformer with several different impedances are used. The matching transformer is connected between coupling capacitor and signal port. In this paper, the developed portable impedance measurement equipment and impedance measurement results are presented. Also impedance matching technique using matching transformers will be explained. We showed the result of the improved performance by the impedance matching.

Impedance Matching Based Control for the Resonance Damping of Microgrids with Multiple Grid Connected Converters

  • Tan, Shulong;Geng, Hua;Yang, Geng
    • Journal of Power Electronics
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    • v.16 no.6
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    • pp.2338-2349
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    • 2016
  • This paper presents an impedance-matching-based control scheme for the harmonic resonance damping of multiple grid-connected-converters (GCCs) with LCL filters. As indicated in this paper, harmonic resonance occurs if a GCC possesses an output impedance that is not matched with the rest of the network in some specific frequency bands. It is also revealed that the resonance frequency is associated with the number of GCCs, the grid impedance and even the capacitive loads. By controlling the grid-side current instead of the converter-side current, the critical LCL filter is restricted as an internal component. Thus, the closed-loop output impedance of the GCC within the filter can be configured. The proposed scheme actively regulates the output impedance of the GCC to match the impedance of the external network, based on the detected resonance frequency. As a result, the resonance risk of multiple GCCs can be avoided, which is beneficial for the plug-and-play property of the GCCs in microgrids. Simulation and experimental results validate the effectiveness of the proposed method.

Detection of High Impedance Fault based on Time Delay Neural Network (시간지연 신경회로망을 이용한 고장지락사고 검출)

  • Choi, Jin-Won;Lee, Chong-Ho;Kim, Choon-Woo
    • Proceedings of the KIEE Conference
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    • pp.405-407
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    • 1994
  • In order to provide reliable power service and to prevent a potentail hazard and damage, it is important to detect high impedance fault in power distribution line. This paper presents a neural network based approach for the detection of high impedance faults. A time delay neural network has been selected and trained for the fault currents obtained from field experiments. Detection experiments have been performed with the data from four different high impedance surfaces. Experimental results indicated the feasibility of using TDNN for the detection of high impedance faults.

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