• Title/Summary/Keyword: THD

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An Experimental Study on Ram Pressure and THD Performance of Pivoted Pad Thrust Bearing (피봇식 주력베어링의 선단압력과 THD성능에 관한 실험적 연구)

  • 박홍규;김경웅
    • Tribology and Lubricants
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    • v.2 no.1
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    • pp.61-68
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    • 1986
  • Effects of the ram-pressure on the THD-performance of pivoted pad thrust bearings are investigated experimentally. A sector-shaped tilting pad thrust bearing and a rotating disk are used. Temperature distribution on the disk surface as well as on the pad surface, distribution of the pressure generated within the fluid film, and the film thickness are measured continuously in the circumferential direction after thermal equilibrium is established. The ram-pressure is proportional to the mean pressure of oil film and to the rotational speed of the disk and affects the maximum pressure and the pressure distribution. The temperature rise on the mating surface of the disc and the pad, contacting with the oil film, is proportional to to the bearing load and the disk speed. The ram-pressure and the temperature rise on the disk surface are dominant factors that affect the THD-performance of pivoted pad thrust bearings.

The power quality measurement of photovoltaic generator and harmonic analysis using THD and TDD (저용량 태양광 발전기의 전기품질 측정 및 THD/TDD를 이용한 고조파 비교분석)

  • Chae, Woo-Kyu;Park, Chang-Ho;Yoon, Gi-Gab;Seo, Jung-Chul
    • Proceedings of the KIEE Conference
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    • pp.545-546
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    • 2006
  • 최근 들어 태양광, 풍력발전 등과 같은 분산전원이 배전계통 곳곳에 연계됨에 따라 전기품질이 저하될 것이라는 우려가 있다. 본 논문에서는 현재 가장 높은 보급률을 보이고 있는 저용량 태양광 발전기가 설치된 수용가를 대상으로 전기품질을 측정하고 '분산형 전원 배전계통연계 기술기준'의 전력품질 만족여부를 분석하였다. 또한 기술기준에서 정한 TDD뿐만 아니라 THD까지 측정하여 해당 지수들의 특성을 비교 분석하였다. 저용량 태양광 발전기가 저압에 연계되었을 경우 Inverter 제작기술의 발달로 전기품질에 큰 영향을 미치지는 않는 것으로 나타났으며 THD보다는 TDD가 분산전원 설치자 측면에서 좀더 여유를 제공함을 알 수 있었다.

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Analysis of Heat Distribution on Switches and THD of 3-Level ANPC VSI for Hybrid Vehicle (하이브리드 자동차용 3-레벨 ANPC 인버터의 열 분배 및 THD 분석)

  • Kim, Mo-Se;Lee, Hee-Jun;Shin, Soo-Chul;Lee, Jung-Hyo;Won, Chung-Yuen;Lee, Taeck-Kie
    • Proceedings of the KIPE Conference
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    • pp.203-204
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    • 2012
  • 본 논문에서는 3-레벨 ANPC 방식을 적용하여 하이브리드 자동차에 장착된 IPMSM을 구동하는 인버터를 제안하였다. 3-레벨 ANPC 인버터는 전력 반도체 스위치의 열 분배에 용이하다. 또한 3-레벨 인버터의 경우 dv/dt가 작기 때문에 THD를 감소시켜 출력 필터의 부피와 EMI를 저감 시킬 수 있다. 따라서 자동차의 신뢰성과 안전성을 높일 수 있다. 제안된 논문에서는 2-레벨 인버터와 3-레벨 ANPC 인버터 출력 특성을 분석하고, 스위치 간 온도 특성 분석 및 THD를 시뮬레이션 통하여 비교하였다.

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Analysis of total harmonic distortion in microspeaker considering coupling effect (연성 효과를 고려한 마이크로스피커 왜율분석)

  • Kwon, Joong-Hak;Kim, Kwang-Suk;Bang, Ki-Chang;Hwang, Sang-Moon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.236-241
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    • 2008
  • With the advent of mobile phone, Digital multimedia broadcasting (DMB) service is to be realized for multimedia data communication. For an acoustic part, a smaller and lighter microspeaker is also soon to be realized as an MP3 song player and a speakerphone. Sound quality in the microspeaker is becoming more important in mobile phones. It is evaluated by total harmonic distortion (THD). THD is the proportion of higher order frequencies output response to sinusoidal input signal. It is affected by uneven magnetic distribution and nonlinear response of diaphragm. In this paper, harmonic distortion is analyzed by considering magnetic and mechanical coupling effects. Simulated results of THD are compared with experimental data. Results show that THD in lower frequency range is higher due to high displace on voice coil and high mechanical response of high order frequency.

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A High Performance Three-Phase Telecom Supply Incorporating a HF Switched Mode Rectifier with a Phase Shifted PWM Controller

  • Shahani, Arushi;Singh, Bhim;Bhuvaneshwari, G.
    • Journal of Power Electronics
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    • v.10 no.3
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    • pp.219-227
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    • 2010
  • Telecom supplies need to conform to low Total Harmonic Distortion (THD) and high Power Factor (PF) as per IEC 61000-3-2 and IEEE 519-1992 standards. These high rating power supplies use a three phase utility in which low THD and high PF are realized via various passive and active wave shaping schemes. In this paper, a new design for three phase telecom power supplies is presented with circuit parameter values optimized for high performance in terms of a low THD, high PF, low ripple and high line and load regulation using a suitable combination of various strategies. The performance of the power supply is validated by extensive simulations.

Analysis of Characteristics for Current Resonant type Boost AC-DC Converter for PFC and Reducing Harmonics (역률개선과 고조파 저감을 위한 전류공진 승압형 AC-DC 컨버터의 특성 해석)

  • Ra, B.H.;Song, D.H.;Suh, K.Y.;Lee, H.W.
    • Proceedings of the KIEE Conference
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    • pp.341-344
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    • 2001
  • In this paper, the characteristics of the proposed converter are show by simulation. As a result, the power factor is improved and the results show the usefulness of the proposed circuit. To improve the hard switching at turn-off of the basic circuit, the circuit using a current resonant switch is proposed. In the proposed circuit, THD of the input current is reduced to 1.8 of the basic circuit. The mechanism of the THD reduction is clarified. That is because the on period becomes shorter at the peak of the source voltage. Using the simulation, the characteristics of the output voltage, current flowing the switch, and THD of the input current are investigated by changing the resonant circuit parameters. Criteria for choosing resonant parameters of smaller THD are obtained.

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The Harmonic Reduction Design of IPMSM No-load line-line Back-EMF for ISG (ISG용 매입형 영구자석 동기 전동기 무부하 선간 역기전력 고조파 저감설계)

  • Lee, Jin-Gyu;Jung, Jae-Woo;Kim, Sung-Il;Hong, Jung-Pyo
    • Proceedings of the KIEE Conference
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    • pp.754-755
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    • 2008
  • This paper presents a method for reducing the Total Harmonic Distortion(THD) of line-line back_EMF of the IPMSM with distributed winding under the no-load condition. Firstly, the specific harmonic components of line-line back EMF are reduced considering with winding factor. Secondly, THD of line-line back EMF is minimized according to change of pole angle using by Space harmonic Analysis. Finally, the optimal design for minimizing the THD is conducted using response surface methodology with finite element analysis. The validity of the design method dealt with in this paper is demonstrated by comparison between the THD of optimal model and initial model.

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Comparative Study of PI, Fuzzy and Fuzzy tuned PI Controllers for Single-Phase AC-DC Three-Level Converter

  • Gnanavadivel, J;Senthil Kumar, N;Yogalakshmi, P
    • Journal of Electrical Engineering and Technology
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    • v.12 no.1
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    • pp.78-90
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    • 2017
  • This paper presents the design of closed loop controllers operating a single-phase AC-DC three-level converter for improving power quality at AC mains. Closed loop inhibits outer voltage controller and inner current controller. Simulations of three level converter with three different voltage and current controller combinations such as PI-Hysteresis, Fuzzy-Hysteresis and Fuzzy tuned PI-Hysteresis are carried out in MATLAB/Simulink. Performance parameters such as input power factor and source current total harmonic distortion (THD) are considered for comparison of the three controller combinations. The fuzzy-tuned PI voltage controller with hysteresis current controller combination provides a better result, with a source-current THD of 0.93% and unity power factor without any source side filter for the three level converter. For load variations of 25% to 100%, a THD of less than 5% is obtained with a maximum value of only 1.67%. Finally, the fuzzy-tuned PI voltage with hysteresis controller combination is implemented in a Xilinx Spartan-6 XC6SLX25 FPGA board for experimental validation of power quality enhancement. A prototype 100 W, 0-24-48 V as output converter is considered for the testing of controller performance. A source-current THD of 1.351% is obtained in the experimental study with a power factor near unity. For load variations of 25% to 100%, the THD is found to be less than 5%, with a maximum value of only 2.698% in the experimental setup which matches with the simulation results.

전자식 안정기용 반도체 ( I ) (역율보상 집적회로)

  • 신동명;이훈철;김덕중
    • 전기의세계
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    • v.42 no.11
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    • pp.19-22
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    • 1993
  • 최근에는 전세계적으로 NOISE에 대한 규제와 아울러 THD를 낮추기 위한 역율개선 전용의 반도체 집적화가 활발하게 진행되고 있다. KA7524는 역률개선을 위해 필요한 회로를 집적화 시켜 제어함으로써 THD를 낮춤은 물론 전자식 안저기및 SMPS등 SYSTEM을 간단하게 하여 제품의 경쟁력을 향상시키는데 도움을 줄 것이다.

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Design of DC Side Voltage and Compensation Analysis of THD for Shunt Power Quality Controller under System Load of Rectifier with R-L Load

  • Zhao, Guopeng;Han, Minxiao
    • Journal of Electrical Engineering and Technology
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    • v.10 no.1
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    • pp.30-40
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    • 2015
  • For a shunt power quality controller (SPQC) the DC side voltage value which is closely related to the compensation performance is a significant parameter. Buy so far, very little discussion has been conducted on this in a quantitative manner by previous publications. In this paper, a method to design the DC side voltage of SPQC is presented according to the compensation performance in the single-phase system and the three-phase system respectively. First, for the reactive current and the harmonic current compensation, a required minimal value of the DC side voltage with a zero total harmonic distortion (THD) of the source current and a unit power factor is obtained for a typical load, through the equivalent circuit analysis and the Fourier Transform analytical expressions. Second, when the DC side voltage of SPQC is lower than the above-obtained minimal value, the quantitative relationship between the DC side voltage and the THD after compensation is also elaborated using the curve diagram. Hardware experimental results verify the design method.