• Title/Summary/Keyword: AC Power Source

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Analysis of electric circuit using capacitor for driving linear compressor (콘덴서를 이용한 선형압축기 구동 전기회로 해석)

  • Ko, Jun-Seok;Kim, Hyo-Bong;Park, Seong-Je;Hong, Yong-Ju;Yeom, Han-Kil;Koh, Deuk-Yong
    • Progress in Superconductivity and Cryogenics
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    • v.14 no.3
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    • pp.43-47
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    • 2012
  • A linear compressor generates pulsating pressure and oscillating flow in a cryocooler such as Stirling cryocooler and pulse tube refrigerator. It is driven by AC power source and designed to operate at resonance of piston motion. The driving voltage level is determined by electric parameters of resistance, inductance and thrust constant of linear motor. From voltage equation on linear motor, the power factor of driving power is inherently less than 1. The phase difference between voltage and current of supplied power can be zero using capacitor and this can minimize a supply voltage level. Especially, the linear compressor of kW class requires high voltage and thus can cause a difficulty in selecting power supply unit due to limitation of voltage level. The capacitor in driving electric circuit is useful to settle this problem. In this study, the electric circuit of linear compressor is analytically investigated with assumption of mechanical resonance. The electric parameters of commercial linear motor are used in the analysis. The effects of capacitor on driving voltage level and power factor are investigated. From analytic results, it is shown that the voltage level can be mimized with using capacitor in driving electric circuit.

A Novel Auxiliary Edge-Resonant Snubber-Assisted Soft Switching PWM High Frequency Inverter with Series Capacitor Compensated Resonant Load for Consumer Induction Heating

  • Ahmed Nabil A.;Iwai Toshiaki;Omori Hideki;Lee Hyun-Woo;Nakaoka Mutsuo
    • Journal of Power Electronics
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    • v.6 no.2
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    • pp.95-103
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    • 2006
  • In this paper, a novel prototype of auxiliary switched capacitor assisted voltage source soft switching PWM Single-Ended Push Pull (SEPP) series capacitor compensated load resonant inverter with two auxiliary edge resonant lossless inductor snubbers is proposed and discussed for small scale consumer high-frequency induction heating (IH) appliances. The operation principle of this inverter is described by using switching mode equivalent circuits. The newly developed multi resonant high-frequency inverter using trench gate IGBTs can regulate its output AC power via constant frequency edge-resonant associated soft switching commutation by using an asymmetrical PWM control or duty cycle control scheme. The brand-new consumer IH products which use the newly proposed edge-resonant soft switching PWM-SEPP type series load resonant high-frequency inverters are evaluated using power regulation characteristics, actual efficiency vs. duty cycle and input power vs. actual efficiency characteristics. Their operating performance compared with some conventional soft switching high-frequency inverters for IH appliances is discussed on the basis of simulation and experimental results. The practical effectiveness of the newly proposed soft switching PWM SEPP series load resonant inverter is verified from an application point of view as being suitable for consumer high-frequency IH appliances.

Virtual Flux and Positive-Sequence Power Based Control of Grid-Interfaced Converters Against Unbalanced and Distorted Grid Conditions

  • Tao, Yukun;Tang, Wenhu
    • Journal of Electrical Engineering and Technology
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    • v.13 no.3
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    • pp.1265-1274
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    • 2018
  • This paper proposes a virtual flux (VF) and positive-sequence power based control strategy to improve the performance of grid-interfaced three-phase voltage source converters against unbalanced and distorted grid conditions. By using a second-order generalized integrator (SOGI) based VF observer, the proposed strategy achieves an AC voltage sensorless and grid frequency adaptive control. Aiming to realize a balanced sinusoidal line current operation, the fundamental positive-sequence component based instantaneous power is utilized as the control variable. Moreover, the fundamental negative-sequence VF feedforward and the harmonic attenuation ability of a sequence component generator are employed to further enhance the unbalance regulation ability and the harmonic tolerance of line currents, respectively. Finally, the proposed scheme is completed by combining the foregoing two elements with a predictive direct power control (PDPC). In order to verify the feasibility and validity of the proposed SOGI-VFPDPC, the scenarios of unbalanced voltage dip, higher harmonic distortion and grid frequency deviation are investigated in simulation and experimental studies. The corresponding results demonstrate that the proposed strategy ensures a balanced sinusoidal line current operation with excellent steady-state and transient behaviors under general grid conditions.

The Analysis of Current Limiting Characteristics Acceding to Fault Angles in the Resistive Type High-Tc Superconducting Fault Current Limiter (저항형 고온초전도 전류제한기의 사고각에 따른 전류제한 특성 분석)

  • Park, Chung-Ryul;Lim, Sung-Hun;Park, Hyoung-Min;Lee, Jong-Hwa;Ko, Seok-Cheol;Choi, Hyo-Sang;Han, Byoung-Sung;Hyun, Ok-Bae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.523-526
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    • 2004
  • According to the continuous demand for power and the growth of electric power utilities, the electric power transmission capacity was increased. The increase of the electric power transmission capacity results in an increase of the fault current level a fault happened. So the superconducting fault current limiter(SFCL) has been reached as the countermeasure for the reduction of the fault current. In this paper, we investigate the fault currents characteristics of resistive type SFCL according to fault angles when AC power source applied. As the fault angles increase, the first peak value of fault current decreased lower. On the other hand, the power burden of SFCL increased.

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Characteristics Analysis of AC Power Source related to Conditions of Series-Arc Generation (직렬아크의 발생 조건과 관련된 교류전원의 특성 해석)

  • Kwon, Wan-Sung;Byen, B.J;Seo, H.U.;Bang, Sun-Bae;Kim, C.M.;Choe, G.H.
    • Proceedings of the KIPE Conference
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    • 2011.11a
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    • pp.34-35
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    • 2011
  • 전기화재의 주요 원인 중 하나인 아크를 검출 및 차단하기 위한 장치로서 아크차단기(AFCI)가 사용되고 있으며 이는 UL1699에서 규정되고 있다. 본 논문에서는 UL1699에서 정의되는 직렬아크의 발생 조건에 따라 아크발생장치를 이용하여 아크를 발생시키고 부하를 변화시켜 아크가 일어날 경우의 교류전원의 특성을 해석하였다.

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Novel Soft Swithing Three - Phase High Power Factor converter (소프트 스위칭형 삼상 고역율 컨버터의 토포로지)

  • Kang, U.J.;Chung, S.H.;Kim, S.D.;Kwak, D.K.;Chun, J.H.;Lee, H.W.
    • Proceedings of the KIEE Conference
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    • 1997.07f
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    • pp.2221-2223
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    • 1997
  • The proposed converter has a merit of simple controlled circuit because the input current control discontinuously. And it is improve to input power factor that the snubber capacitor's energy regenerate to the AC source side. Specially using the discontinuous current mode in the reactor. This topology is reduced a current /voltage stresses of resonant devices in addition to a partial resonant strategy. The result of simulations of the proposed topology included in this paper.

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Design of Advanced Static Var Compensator(ASVC) for Distribution Line (배전선로 적용을 위한 새로운 무효전력보상치(ASVC)의 설계)

  • Min, Wan-Ki;Lee, Sang-Hun;Choi, Jae-Ho
    • Proceedings of the KIEE Conference
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    • 1997.07f
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    • pp.2010-2012
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    • 1997
  • A cascade multilevel voltage source inverter is introduced to apply the advanced static var compensator(ASVC) for large scale power application. This cascade M-level inverter consists of (M-1)/2 single-phase full bridges. This inverter is suitable to the flexible ac transmission systems(FACTS) including SVC, series compensation and phase shifting. It can solve the problems of conventional transformer -based multipulse inverters and multilevel diode-clamped inverters. From the simulation results, the validity of ASVC with cascade multilevel inverter is shown for high power application.

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A Study on the Converter Drive by Means of Series and Parallel Connection (콘버어터 직병렬 접속 운전에 관한 연구)

  • Chung, Yon-Tack;Seo, Yong-Soo;Hwang, Lak-Hoon
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.33 no.9
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    • pp.347-354
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    • 1984
  • This paper presents a method of improving the power factor and , the waveform of A.C line currents and the output waveforms of AC to DC fully bridge converter systems which is achieved by connecting CON I.II and CON III.IV in series and parallel. The basic principle of the CON I.II.III.IV's operation is simple and feasibility of thease converter is proved by experiments. CON I and CON III are constructed of natural commutation, CON II and CON IV are constructed of forced commutation. The experimental results show that the power factor and waveform of the source currents and the output waveforms are improved by the method of connecting converter in series and parallel and driving it in I, II, III, IV quadrant.

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Dynamic Performance Analysis for Different Vector-Controlled CSI- Fed Induction Motor Drives

  • Mark, Arul Prasanna;Irudayaraj, Gerald Christopher Raj;Vairamani, Rajasekaran;Mylsamy, Kaliamoorthy
    • Journal of Power Electronics
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    • v.14 no.5
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    • pp.989-999
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    • 2014
  • High-performance Current Source Inverter (CSI)-fed, variable speed alternating current drives are prepared for various industrial applications. CSI-fed Induction Motor (IM) drives are managed by using different control methods. Noteworthy methods include scalar Control (V/f), Input-Output Linearization (IOL) control, Field-Oriented Control (FOC), and Direct Torque Control (DTC). The objective of this work is to compare the dynamic performance of the aforementioned drive control methods for CSI-fed IM drives. The dynamic performance results of the proposed drives are individually analyzed through sensitivity tests. The tests selected for the comparison are step changes in the reference speed and torque of the motor drive. The operation and performance of different vector control methods are verified through simulations with MATLAB/Simulink and experimental results.

Drive of induction motor using three-phase inverter and voltage type PWM single-phase converter (전압형 PWM 단상 컨버터와 3상 인버터를 이용한 유도전동기의 운전)

  • 문상필;서기영;이현우;강욱중
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.15 no.3
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    • pp.18-24
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    • 2001
  • This paper deals with a three-phase Pulse width Modulation(PWM) voltage souse inverter-induction motor drive with a single-phase PWM converter. The single-phase system has the pulsating instantaneous power with twice the frequency of the ac source. The power pulsation generates the dc voltage pulsation of the converter. In result, the waveforms of the inverter output current and voltage are distorted. The steady-stare operations of the system are analyzed by employing a state-spare method Such everything confirmed it's validity throughout simulation and experiment.

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