• Title/Summary/Keyword: harmonic-analysis

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A Study on the Power Factor Correction and Harmonics Reduction of Capacitor Banks installed at Customers (수용가에 설치된 캐패시터 뱅크의 역률개선 및 고조파 저감에 관한 연구)

  • Kim, Kyung-Chul;Choi, Hyoung-Bumb
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.8
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    • pp.12-17
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    • 2008
  • Most power system loads and delivery apparatus are inductive in nature and therefore operate at a lagging power factor. Applying capacitor banks to a customer will result in a power factor correction and other benefits such as VAR support, increased voltage, reduced power losses, and reduced billing charges. Also there can be power quality problems as a result of adding capacitor banks. The most common are harmonics. This paper provides an in depth analysis on the power factor correction and harmonics reduction of capacitor bank installed at a customer. The EDSA program was used as a simulation tool for the case study.

Cascaded-transformer-based 3$^{n-1}$+2 level PWM Inverter (다단 변압기 기반 3$^{n-1}$+2 레벨 PWM 인버터)

  • Kang, Feel-Soon;Park, Jin-Hyun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.2
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    • pp.681-684
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    • 2005
  • This paper presents a useful multilevel PWM inverter scheme based on a (3$^{n-1}$+2) level generation technique. It consists of a PWM inverter, an assembly of LEVEL inverters, and cascaded transformers. To produce high quality output voltage waves, it synthesizes a large number of output voltage levels using cascaded transformers, which have a series-connected secondary. By a suitable selection of secondary turn-ration of the transformer, the amplitude of an output voltage is appeared at the rate of an integer to an input dc source. Operational principles and analysis are illustrated in depth. The validity of the proposed system is verified through computer-aided simulations and experimental results using prototypes generation output voltages of an 11-level and a 29-level, respectively. And their results are compared with conventional counterparts.

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Prediction of Aerodynamic Stability Derivatives of Shell Configuration of Missile Using CFD Method (CFD를 이용한 유도탄 덮개 형상의 공력 미계수 예측)

  • Kang, Eunji
    • Journal of the Korea Institute of Military Science and Technology
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    • v.23 no.4
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    • pp.363-370
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    • 2020
  • In this study, pitching stability derivatives of the conical shell configuration is predicted using commercial CFD code. Unsteady flow analysis with forced harmonic motion of the model is performed using overset mesh. The test is conducted about Basic finner missile configuration. The static and dynamic stability derivatives are good agreement with available experimental data. As the same way, a conical shell is analyzed in Mach number 1.6 and various reduced frequency. The static and dynamic derivatives are obtained from the time-pitching moment coefficient histories in each of four cases of mean angle of attack. The variation of reduced frequency is not affected static and dynamic derivatives. Increasing the mean angle of attack, static derivatives are increased slowly. Comparison of the Cm curves at the steady and unsteady state results shows that the Cm curve including the damping effect is lower than otherwise case, approximately 9-18 %.

Distortion Elimination for Buck PFC Converter with Power Factor Improvement

  • Xu, Jiangtao;Zhu, Meng;Yao, Suying
    • Journal of Power Electronics
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    • v.15 no.1
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    • pp.10-17
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    • 2015
  • A quasi-constant on-time controlled buck front end in combined discontinuous conduction mode and boundary conduction mode is proposed to improve power factor (PF).When instantaneous AC input voltage is lower than the output bus voltage per period, the buck converter turns into buck-boost converter with the addition of a level comparator to compare input voltage and output voltage. The gate drive voltage is provided by an additional oscillator during distortion time to eliminate the cross-over distortion of the input current. This high PF comes from the avoidance of the input current distortion, thereby enabling energy to be delivered constantly. This paper presents a series analysis of controlling techniques and efficiency, PF, and total harmonic distortion. A comparison in terms of efficiency and PF between the proposed converter and a previous work is performed. The specifications of the converter include the following: input AC voltage is from 90V to 264V, output DC voltage is 80V, and output power is 94W.This converter can achieve PF of 98.74% and efficiency of 97.21% in 220V AC input voltage process.

A Bridgeless Single Stage AC-DC Converter for Wireless Power Charging System (무선전력충전시스템을 위한 브리지리스 단일전력단 교류-직류 컨버터)

  • Kim, Min-Ji;Yoo, Sang-Jae;Yoo, Kyung-Jong;Woo, Jung-Won;Kim, Eun-Soo;Hwang, In-Gab
    • The Transactions of the Korean Institute of Power Electronics
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    • v.25 no.1
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    • pp.44-53
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    • 2020
  • A bridgeless single-stage AC-DC converter for wireless power charging systems is proposed. This converter is composed of a PFC stage and a three-level hybrid DC-DC stage. The proposed converter can control the wide output voltage (200-450 VDC) by the variable link voltage and the pulse-width voltage applied to the primary resonant circuit due to the phase-shifted modulation at a fixed switching frequency. Moreover, the input power factor and the total harmonic distortion can be improved by using the proposed converter. A 1 kW prototype was fabricated and validated through experimental results and analysis.

The 1.6[kW] Class Single Phase ZCS-PWM High Power Factor Boost Rectifier (1.6[kW]급 단상 ZCS-PWM HPF 승압형 정류기)

  • Mun, S.P.;Kim, S.I.;Yun, Y.T.;Kim, Y.M.;Lee, H.W.;Suh, K.Y.
    • Proceedings of the KIEE Conference
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    • 2003.07b
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    • pp.1169-1171
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    • 2003
  • This paper presents a 1.6[kW]class single phase high power factor(HPF) pulse width modulation(PWM) boost rectifier featuring soft commutation of the active switches at zero current. It incorporates the most desirable properties of conventional PWM and soft switching resonant techniques. The input current shaping is achieved with average current mode control and continuous inductor current mode. This new PWM converter provides zero current turn on and turn off of the active switches, and it is suitable for high power applications employing insulated gate bipolar transistors(IGBT'S). The principle of operation, the theoretical analysis, a design example, and experimental results from laboratory prototype rated at 1.6[kW] with 400[Vdc] output voltage are presented. The measured efficiency and the power factor were 96.2[%] and 0.99[%], respectively, with an input current Total Harmonic Distortion(THD) equal to 3.94[%], for an input voltage with THD equal to 3.8[%], at rated load.

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Determination of the Degree of Nonlinearity in the Response of Offshore Structures Using Higher Order Transfer Functions (고차 전이함수를 이용한 해양구조물 거동의 비선형도 결정)

  • 백인열
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.7 no.1
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    • pp.116-125
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    • 1995
  • Higher order nonlinear transfer functions are applied to model the nonlinear responses obtained Inn dynamic analysis of single degree of freedom systems (SDOF) subjected to wave and current loadings. The structural systems are subjected to single harmonic, two wave combination and irregular wave loading. Three different sources of nonlinearities are examined for each of the wave loading condition and it is shown that the nonlinear response appear at the resonance frequencies of the SDOF even when virtually no wave energy exists at those resonance frequencies. Higher order nonlinear transfer functions based on Volterra series representation are used to model the nonlinear responses mainly f3r the flexible systems and clearly shows the degrees of nonlinearity either as quadratic or cubic.

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Class E Power Amplifiers using High-Q Inductors for Loosely Coupled Wireless Power Transfer System

  • Yang, Jong-Ryul;Kim, Jinwook;Park, Young-Jin
    • Journal of Electrical Engineering and Technology
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    • v.9 no.2
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    • pp.569-575
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    • 2014
  • A highly efficient class E power amplifier is demonstrated for application to wireless power transfer system. The amplifier is designed with an L-type matching at the output for harmonic rejection and output matching. The power loss and the effect of each component in the amplifier with the matching circuit are analyzed with the current ratio transmitted to the output load. Inductors with a quality factor of more than 120 are used in a dc feed and the matching circuit to improve transmission efficiency. The single-ended amplifier with 20 V supply voltage shows 7.7 W output power and 90.8% power added efficiency at 6.78 MHz. The wireless power transfer (WPT) system with the amplifier shows 5.4 W transmitted power and 82.3% overall efficiency. The analysis and measurements show that high-Q inductors are required for the amplifier design to realize highly efficient WPT system.

A New 24-Pulse Diode Rectifier for High Voltage and High Power Application (새로운 고전압 대전력용 24펄스 다이오드 정류기 시스템)

  • 최세완;김기용
    • The Transactions of the Korean Institute of Power Electronics
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    • v.4 no.3
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    • pp.304-309
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    • 1999
  • In this paper, a new 24longleftarrowpulse diode rectifier system based upon the conventional series-connected 12-pulse rectifier is p proposed with the least number of switching devices and low VA rating of the additional passive components. The p proposed approach does not employ any active switching devices. Therefore, the system is rugged and simple to i implement. Detailed analysis with VA rating calculation of the components is presented and experimental results from a a 220V, 3kV A rectifier system verify the proposed concept.

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Analysis of Inductively Coupled Plasma using Electrostatic Probe and Fluid Simulation (정전 탐침법과 유체 시뮬레이션을 이용한 유도결합 Ar 플라즈마의 특성 연구)

  • Cha, Ju-Hong;Lee, Ho-Jun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.7
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    • pp.1211-1217
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    • 2016
  • Discharge characteristics of inductively coupled plasma were investigated by using electrostatic probe and fluid simulation. The Inductively Coupled Plasma source driven by 13.56 Mhz was prepared. The signal attenuation ratios of the electrostatic probe at first and second harmonic frequency was tuned in 13.56Mhz and 27.12Mhz respectively. Electron temperature, electron density, plasma potential, electron energy distribution function and electron energy probability function were investigated by using the electrostatic probe. Experiment results were compared with the fluid simulation results. Ar plasma fluid simulations including Navier-Stokes equations were calculated under the same experiment conditions, and the dependencies of plasma parameters on process parameters were well agreed with simulation results. Because of the reason that the more collision happens in high pressure condition, plasma potential and electron temperature got lower as the pressure was higher and the input power was higher, but Electron density was higher under the same condition. Due to the same reason, the electron energy distribution was widening as the pressure was lower. And the electron density was higher, as close to the gas inlet place. It was found that gas flow field significantly affect to spatial distribution of electron density and temperature.