• Title/Summary/Keyword: Variable Capacitor

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Tunable Bandpass 4th Order SC Sigma-delta Modulator with Novel Structure (새로운 구조의 Tunable 4차 SC Bandpass Sigma-Delta 변조기)

  • Kim, Jae-Bung;Yoo, Nam-Hee;Cho, Seong-Ik
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.2
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    • pp.446-450
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    • 2011
  • Tunable SC(Switched Capacitor) bandpass ${\Sigma}-{\Delta}$(Sigma-Delta) modulator used in wireless system receiver occurs a signal attenuation according to tuning of center frequency in signal bandwidth. In this paper, tunable bandpass 4th order SC bandpass ${\Sigma}-{\Delta}$ modulator with novel structure is proposed for rejection of signal attenuation in signal bandwidth. The existing structure uses a ten variable coefficient values for rejection of signal reduction in the modulator. But the proposed structure only use a two variable coefficient values for rejection of signal attenuation in the modulator. Also, an adder and comparator is replaced with a comparator having 4 inputs in the modulator. Therefore, the existing structure has one more OP-AMP. The purposed modulator was designed in $0.18\;{\mu}m$ CMOS technology. The resolution of the modulator within 310 kHz bandwidth and 40 MHz sampling frequency under 6.67 MHz, 10 MHz and 13.33 MHz intermediate frequency are over 10 bit.

Fabrication of Silicon Voltage Variable Capacitance Diode-(I) (VVC 다이오드의 시작연구 (I))

  • 정만영;박계영
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.5 no.3
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    • pp.9-24
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    • 1968
  • This report is concerned with the optimum design of hyper-aprupt p-n junctiea silion diode and fabriction of this diode usable for electrical tuning application. Impurity profile in the junction was assumed to clean exponential function. With this assunntion, an optimum criterion for designing standard AM radio tuning capacitor was derived. In the diffusion process, after aluminum and antimony as impurties were deposited in vacuum on a P-type silicon wafer, the diffusion was followed by loading the wafer into the high temperature furnace.

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The Output Characteristics of Transcranial Magnetic Stimulation with Voltage Variable Capacitor-Charging System

  • Kim, Whi-Young
    • Journal of information and communication convergence engineering
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    • v.8 no.2
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    • pp.205-211
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    • 2010
  • In this study, a Magnetic stimulation Pulse Train control technique is introduced and applied to Flyback converter operating in discontinuous conduction mode. In contrast to the conventional pulse width modulation control scheme, the principal idea of a Magnetic stimulation Pulse Train is to achieve output voltage regulation using high and low power pulses. The proposed technique is applicable to any converter operating in discontinuous conduction. However, this work mainly focuses on Flyback topology. In this paper, the main mathematical concept of the new control algorithm is introduced and simulations as well as experimental results are presented.

Erasing characteristic improvement in SONOS type with engineered tunnel barrier (Engineered tunnel barrier를 갖는 SONOS 소자에서의 소거 속도 향상)

  • Park, Goon-Ho;You, Hee-Wook;Oh, Se-Man;Kim, Min-Soo;Jung, Jong-Wan;Lee, Young-Hie;Chung, Hong-Bay;Cho, Won-Ju
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.97-98
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    • 2009
  • Tunneling barrier engineered charge trap flash (TBE-CTF) memory capacitor were fabricated using the tunneling barrier engineering technique. Variable oxide thickness (VARIOT) barrier and CRESTED barrier consisting of thin $SiO_2$ and $Si_3N_4$ dielectrics layers were used as engineered tunneling barrier. The charge trapping characteristic with different metal gates are also investigated. A larger memory window was achieved from the TBE-CTF memory with high workfunction metal gate.

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High Impedance Fault Detection using Wavelet Transform (Wavelet 변환을 이용한 고저항 지락고장 검출)

  • Kim, Hyun;Kim, Chul-Hwan
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.12
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    • pp.1492-1497
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    • 1999
  • High impedance fault(HIF) is defined as fault the general overcurrent relay can not detect or interrupt. Especially when HIF occur in residential areas, energized high voltage conductor results in fire hazard, equipment damage or personal threat. This paper proposes the model of the high impedance fault in transmission line using the ZnO arrester and resistance to be implemented within EMTP. The performance of the proposed model is tested on a typical 154[kV] korean transmission line system under various fault conditions. Wavelet transform is efficient and useful for the detection of high impedance fault in power system, because it uses variable windows according to frequency. In this paper, HIF detection method using wavelet transform can distinguish HIF form similar fault like arcfurance load, capacitor bank switching and line switching.

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A New Frequency Controlled Half-bridge Converter with Hold-up Time Extension Circuit

  • Kim, Duk-You;Kim, Jae-Kuk;Lee, Woo-Jin;Moon, Gun-Woo
    • Proceedings of the KIPE Conference
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    • 2008.06a
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    • pp.382-384
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    • 2008
  • Hold-up time is a special requirement for the front end DC/DC converter in a server power supply. It forces the converter with the variable switching frequency to operate in a wide switching frequency range, which makes the regulation difficult and reduces the power density. In this paper a novel frequency controlled half bridge converter with the hold-up time extension circuit is proposed. During the hold-up time, the auxiliary switches are turned on, thus the resonant inductance is reduced and the voltage conversion ratio is increased. Therefore, the output capacitor of the power factor correction (PFC) circuit can be decreased, and the converter can have high power density. The proposed converter is verified by experimental results from a prototype with 700W, 400V input, and 12V output.

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Design and Implementation of Power Conversion Unit(PCU) for Motor of Electric Vehicle (전기자동차 모터구동용 전력변환장치(PCU) 설계 및 구현)

  • Kim, Mal-Soo;Kim, Seung-Mo;Huh, Nam-Euk;Oh, Seung-Jin;Nam, Kwang-Hee
    • Proceedings of the KIPE Conference
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    • 2012.11a
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    • pp.201-202
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    • 2012
  • This paper presents design and implementation of the PCU(150 kVA 3-Phase PWM Inverter for Electric Vehicles). For Implementation of the PCU, it is consist with Case, Connectors, IGBT module for PWM switching, DC-capacitor for dc-source, resolver for sensing of speed & position, and PCB board for control & gate-driver. Also, for the purpose of stable operation of the PCU in vehicle with variable torque condition in motor, current control scheme based on torque-map are developed. According to real-car test mode, the prototype of proposed the PCU is verified with performance and stability. Thus, design and implement of the PCU are discussed, and experimental results are presented in this paper.

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A SVPWM for the Small Fluctuation of Neutral Point Current in Three-level Inverter (중성점 전류 리플을 고려한 3-레벨 인버터의 공간 벡터 펄스폭 변조 기법)

  • 김래영;이요한;현동석
    • Proceedings of the KIPE Conference
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    • 1998.11a
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    • pp.33-37
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    • 1998
  • For the high power variable speed applications, the DCTLI(diode clamped three-level inverter) have been widely used. This paper describes the analysis of the neutral point current of the DCTLI and the improved space vector-based PWM strategy considering the switching frequency of power devices, that minimizes the fluctuation of the neutral point current in spite of high modulation index region and low power factor. It contributes to decrease the capacitance of dc-link capacitor bank and to increase the neutral point voltage controllable region. Especially, even if second (or even) order harmonic is induced in load current (at this situation, is was investigated that the general control method can not suppress the neutral point voltage variation), this PWM can provide effective control method to suppress the neutral point voltage variation. Various simulation results by means of Matlab/Simulation are presented to verify the proposed PWM.

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Fault Detection and Classification of Hi9h Impedance Fault using Wavelet Transform (웨이브렛 변환을 이용한 고저항 지락사고 검출 및 판별)

  • Ko, Y.H.;Kim, C.H.;Kim, H.
    • Proceedings of the KIEE Conference
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    • 1999.07c
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    • pp.1373-1375
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    • 1999
  • High impedance fault (HIF) is defined as fault the general overcurrent relay can not detect or interrupt. Especially when HIF occur in residential areas, energized high voltage conductor results in fire hazard, equiment damage or personal threat. This paper proposes the model of HIF in transmission line using the ZnO arrester and resistance to be implemented within EMTP. Wavelet transform is efficient and useful for the detection of HIF in power system, because it uses variable windows according to frequency. HIF detection method using wavelet transform can distinguish HIF from similar phenomena like arcfurance load, capacitor bank switching and line switching.

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Electrical characteristic of $SiO_2/HfO_2/Al_2O_3$ (OHA) as engineered tunnel barrier with various heat treatment condition ($SiO_2/HfO_2/Al_2O_3$ (OHA) 터널 장벽의 열처리 조건에 따른 전기적 특성)

  • Son, Jung-Woo;Cho, Won-Ju
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.344-344
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    • 2010
  • A capacitor with engineered tunnel barrier composed of High-k materials has been fabricated. Variable oxide thickness (VARIOT) barrier consisting of thin SiO2/HfO2/Al2O3 (2/1/3 nm) dielectric layers were used as engineered tunneling barrier. We studied the electrical characteristics of multi stacked tunnel layers for various RTA (Rapid Thermal Anneal) and FGA (Forming Gas Anneal) temperature.

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