• Title/Summary/Keyword: Short circuit frequency

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A High Voltage Power Supply for X-Ray Tube Using High Frequency (고주파 인버터식 X-선관용 고전압 전원장치)

  • Kim, H.S.;Yoo, D.W.;Cho, J.G.;Back, J.W.;Rim, G.H.;Won, C.Y.
    • Proceedings of the KIEE Conference
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    • 1997.07f
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    • pp.2246-2248
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    • 1997
  • This paper presents a high-frequency inverter type high-voltage power supply for X-ray equipments. The high-voltage generator consist of an inverter unit including the SR(Series Resonance) type PSC(Phase-Shifted Control) PWM circuit adopting IGBT as the switching power device and high-voltage unit including the CW(Cockcroft Walton) circuit. When the X-ray equipment is radiographing at large power for a short time, this generator operates through feedback voltage mode control to obtain a high speed leading edge and low ripple. The operating modes and design consideration of the proposed power supply are given. Issues in the design of high-voltage divider for high voltage measuring. Experimental results are presented to verify the performance of the designed power supply for varying load conditions. The proposed apparatus has several advantages, e.g., the fast rising time of tube voltage, accuracy and reduced component size etc.

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Design, Implementation and Testing of HF transformers for Satellite EPS Applications

  • Zahran, Mohamed
    • Journal of Power Electronics
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    • v.8 no.3
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    • pp.217-227
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    • 2008
  • The electric power subsystems (EPS) of most remote sensing satellites consist of a solar array as a source of energy, a storage battery, a power management and control (PMC) unit and a charge equalization unit (CEU) for the storage battery. The PMC and CEU use high frequency transformers in their power modules. This paper presents a design, implementation and testing results of a high frequency transformer for the EPS of satellite applications. Two approaches are used in the design process of the transformer based on the pre-determined transformer specifications. The transformer is designed based on an ETD 29 ferrite core. The implemented transformer consists of one center-tapped primary coil with eleven center-tapped secondary coils. The offline calculation results and measured values of R, L for transformer coils are convergence. A test circuit for measuring the transformer parameters like voltage, current and B-H hysteresis was implemented and applied. The test results confirm that the voltage waveforms of both primary and secondary coils were as desired. No overlapping occurred between the control signal and the transformer, which was not saturated during testing even during a short circuit test of the secondary channels. The dynamic B-H loop characteristics of the used transformer cores were measured. The sample test results are given in this paper.

Frequency response of Photovoltaic Cell using ZnPc (ZnPc를 이용한 유기태양전지의 주파수 응답 특성)

  • Ahn, Joon-Ho;Kim, Ho-Sik;Park, Jae-Joon;Lee, Won-Jae;Jang, Kyung-Uk;Seo, Dae-Sik;Kim, Tae-Wan;Lee, Joon-Ung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.11a
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    • pp.285-286
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    • 2005
  • Organic photovoltaic properties were studied in ZnPc/$C_{60}$ heterojunction structure by varying the organic layer thicknesses and exiton blocking layer(EBL). Current density-voltage characteristics of organic photovoltaic cells were measured using Keithley 236 source-measure unit, a 500W xenon lamp (ORIEL 66021) for a light source and Agilent 4294A impedance analyzer in the range of 40 Hz $\sim$ 1 MHz. From the analyses of current-voltage characteristics such as short-circuit current density, open-circuit voltage and power conversion efficiency, optimum thickness of the organic layer were obtained and frequency response such as electrical conductance.

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Capacitor Failure Detection Technique for Microgrid Power Converter (마이크로그리드 전력변환장치용 커패시터 고장 검출 기법)

  • Woo-Hyun Lee;Gyang-Cheol Song;Jun-Jae An;Seong-Mi Park;Sung-Jun Park
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.6_2
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    • pp.1117-1125
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    • 2023
  • The DC part of the DC microgrid power conversion system uses capacitors for buffers of charge and discharge energy for smoothing voltage and plays important roles such as high frequency component absorption, power balancing, and voltage ripple reduction. The capacitor uses an aluminum electrolytic capacitor, which has advantages of capacity, low price, and relatively fast charging/discharging characteristics. Aluminum electrolytic capacitors(AEC) have previous advantages, but over time, the capacity of the capacitors decreases due to deterioration and an increase in internal temperature, resulting in a decrease in use efficiency or an accident such as steam extraction due to electrolyte evaporation. It is necessary to take measures to prevent accidents because the failure diagnosis and detection of such capacitors are a very important part of the long-term operation, safety of use, and reliability of the power conversion system because the failure of the capacitor leads to not only a single problem but also a short circuit accident of the power conversion system.

New UWB BPF with Steep Selectivity Based on T-Resonator and Capacitively Coupled λ/4 and λ/2 Line Sections

  • Duong, Thai Hoa;Kim, Ihn-Seok
    • Journal of electromagnetic engineering and science
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    • v.9 no.3
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    • pp.164-173
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    • 2009
  • In this paper, two new circuit structures for European and U.S. ultra-wide band(UWB) bandpass filters(BPFs) with sharp roll-off characteristics are introduced. We show first that the ultra-wide bandpass property is obtained from a $\lambda$/4 open T resonator with a capacitively coupled $\lambda$/4 short-circuited line, which provides two attenuation poles at lower and upper cutoff frequencies. Then, two identical capacitively coupled input/output lines, which can be $\lambda$/4-length open ends or $\lambda$/2-length short ends, with the T-resonator, are adopted to suppress lower and higher frequency components outside of the pass band. There is coupling between the input and output lines providing two additional transmission zeros in the lower and upper transition bands of the filter. Since the coupling between the T-resonator with the $\lambda$/4 short-circuited line and the input/output lines limits the bandwidth of the filter to the European UWB band, both the $\lambda$/4 short-circuited line and the input/output lines are inserted between the two stacked T-resonators for the U.S. UWB band. The filter structures are simulated with ADS and HFSS and realized with low-temperature co-fired ceramic(LTCC) green tape which has the dielectric constant of 7.8. Measurement results agree well with HFSS simulation results.

High-Frequency Parameter Extraction of Insulating Transformer Using S-Parameter Measurement (S-파라메타를 이용한 절연 변압기의 고주파 파라메타 추출)

  • Kim, Sung-Jun;Ryu, Soo-Jung;Kim, Tae-Ho;Kim, Jong-Hyeon;Nah, Wan-Soo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.25 no.3
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    • pp.259-268
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    • 2014
  • In this paper, we suggest a method of extracting circuit parameters of the insulating transformer using S-parameter measurement, especially in high frequency range. At 60 Hz, conventionally, no load test and short circuit test are used to extract the circuit parameters. In this paper S-parameters measured from VNA(Vector Network Analyzer) were used to extract the transformer parameters using data fitting method (optimization). The S-parameters from the equivalent circuit using the extracted parameters showed good agreement with those from measurement. Furthermore, the transformer secondary voltages from the equivalent circuit model also coincide quite exactly to the measured secondary voltages in sinusoidal forms. Finally we assert that the proposed method to extract the parameters for the insulating transformer using S-parameter is valid especially in high frequency.

Development of Short-Wavelength Transmission Line Employing Periodically Perforated Ground Metal for Application to Miniaturized On-chip Passive Components on Si RFIC (Si RFIC상의 온칩 수동소자에의 응용을 위한 주기적 접지 금속막 선로를 이용한 단파장 전송선로 개발)

  • Joh, Han-Nah;Park, Young-Bae;Yun, Young
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.2
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    • pp.330-335
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    • 2008
  • In this study, highly miniaturized short-wavelength transmission line employing periodically perforated ground metal (PPGM) structures were developed for application to miniaturized on-chip passive component on Si RFIC. The transmission line employing PPGM structure showed shorter wavelength and lower characteristic impedance than conventional coplanar-type transmission line. The wavelength of the transmission line employing PPGM structure was 57% of the conventional coplanar-type transmission line on Si Radio Frequency Integrated Circuit (RFIC) substrate. Basic characteristics of the transmission line employing PPGM structure were also investigated in order to evaluate its suitability for application to a development of miniaturized passive on-chip components. According to the results, it was found that the PPGM structure is a promising candidate for application to a development of miniaturized on-chip passive components on Si RFIC.

The reduction of spatter in $CO_2$ inverter Arc Weling machine by the current control at the moment of short (단락순간의 전류제어에 의한 $CO_2$ 인버터 아크 용접기의 스패터 저감)

  • 고재석;채영민;이승요;목형수;최규하
    • Proceedings of the KIPE Conference
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    • 1999.07a
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    • pp.585-590
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    • 1999
  • The conventional $CO_2$ inverter arc machine has constant voltage output characteristic and uses constant wire speed controller for welding current control. By adoption of PWM inverter to the welding machine, the spattering was reduced rather than the thyrister arc welding machine or AC arc welding machine. Moreover, by the high switching frequency, the output reactor size could be reduced evidently. Recently, the studies on optimal voltage and current waveform for the welding performance improvement have been studied. In this paper, a new instantaneous output current control scheme during the short circuit mode was proposed and showed the capability of arc stability improvement and the reduction of spatter generation.

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Design of New Switching Structure for Time Division Duplex system (시분할 통신 시스템을 위한 새로운 구조의 스위칭회로 설계)

  • Kim, Kwi-Soo;Lim, Jong-Sik;Ahn, Dal
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.8 no.5
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    • pp.1076-1081
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    • 2007
  • In this paper, we propose a new switch structure for time division duplex(TDD) system. The existing TDD structure utilizes a circulator fur isolation characteristic between ports. However, the circulator produces intermodulation distortion signals which are undesired signal because of its nonlinear properties. The proposed circuit is composed of a modified branch-line hybrid coupler which controls the signal flow while the isolated port is open-/short- terminated. In order to prove the validity of the presented structure, the switch circuit is fabricated and measured at 2.3GHz, the center frequency of Wibro service system.

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Water-Sloshing-Based Electricity Generating Device via Charge Separation and Accumulation (전하 분리와 축적을 통한 물의 슬로싱 현상 기반 전기에너지 발생 장치)

  • Cha, Kyunghwan;Heo, Deokjae;Lee, Sangmin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.1
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    • pp.98-101
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    • 2022
  • Liquid-based Triboelectric nanogenerator (L-TENG) is one of the alternatives to solid-based Triboelectric nanogenerator (S-TENG) because of the absence of surface damage which can decrease the durability of the generator. However, the L-TENG also has an obvious drawback of significantly lower output than that of S-TENG. This article produces water-sloshing-based electricity generating device (W-ED) with a new design of L-TENG that improves electrical output in portable form. The dual-electrode system, consisting of closed-loop circuit and inner electrode which enables water to contact directly in the bottle, can generate the open-circuit voltage and the short-circuit current of up to 348 V and 5.1 mA, respectively. By investigating the motion of water for each frequency, we propose that W-ED is suitable device for a variety of human motions. We expect that W-ED can be applied in small electrical devices or sensors in daily-use items.