• Title/Summary/Keyword: PWM Method

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Parallel Operation Method using New Cubic Equation Droop Control of Three-Phase AC/DC PWM Converter for DC Distribution Systems (DC배전용 3상 AC/DC PWM 컨버터의 새로운 3차방정식 Droop 제어를 적용한 병렬운전 기법)

  • Shin, Soo-Choel;Lee, Hee-Jun;Park, Yun-Wook;Hong, Seok-Jin;Won, Chung-Yuen
    • The Transactions of the Korean Institute of Power Electronics
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    • v.19 no.3
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    • pp.233-239
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    • 2014
  • This paper proposes that each converter supplies the power using the proposed droop control for the parallel operation of the converters. The proposed method is easy to increase the power as parallel system in DC distribution. By improving conventional droop-control method used in AC grid newly, a droop controller is designed to apply droop control in DC grid. And the control method of the proposed droop controller is explained particularly. In this paper, by applying the proposed control method to DC distribution system, propriety is verified through the simulation and the experiment.

Current Decoupling Control for the Three-level PWM Rectifier with a Low Switching Frequency

  • Yuan, Qing-Qing;Xia, Kun
    • Journal of Electrical Engineering and Technology
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    • v.10 no.1
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    • pp.280-287
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    • 2015
  • Three-level PWM rectifiers applied in medium voltage applications usually operate at low switching frequency to keep the dynamic losses under permitted level. However, low switching frequency brings a heavy cross-coupling between the current components $i_d$ and $i_q$ with a poor dynamic system performance and a harmonic distortion in the grid-connecting current. To overcome these problems, a mathematical model based on complex variables of the three-level voltage source PWM rectifier is firstly established, and the reasons of above issues resulted from low switching frequency have been analyzed using modern control theory. Then, a novel control strategy suitable for the current decoupling control based on the complex variables for $i_d$ and $i_q$ is designed here. The comparisons between this kind of control strategy and the normal PI method have been carried out. MATLAB and experimental results are given in detail.

A New Overmodulation Method to Extend Linearity Region of a PWM Inverter (PWM 인버터에서 선형영역 확장을 위한 새로운 과변조 기법)

  • Kim, Sang-Hoon;Han, Dae-Woong
    • Journal of Industrial Technology
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    • v.21 no.B
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    • pp.59-66
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    • 2001
  • In this paper, a novel overmodulation strategy for PWM inverters to extend linearity region is presented. The proposed strategy uses the concept of space-vector PWM(SVPWM) based on the zero sequence signal(offset voltage) injection principle. So, by modifying the pole voltage simply, the linear control of inverter output voltage over the whole overmodulation range can be achieved easily. The proposed strategy is so simple that its practical implementation is easy. The validity of the proposed strategy is confirmed by the experimental results.

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Switch Open Fault Detection and Tolerant Method for Three Phase PWM Rectifier (3상 PWM 정류기의 스위치 개방 고장시 감지 및 허용운전 방법)

  • Shin, Hee-Kuen;An, Byoung-Woong;Kim, Hag-Wone;Cho, Kwan-Yuhl;Lim, Byung-Kuk;Jung, Shin-Myung
    • Proceedings of the KIPE Conference
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    • 2011.11a
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    • pp.18-19
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    • 2011
  • 본 논문에서는 3상 PWM 정류기의 스위치 개방 고장시 감지 및 허용 운전 방법에 대해 제안한다. 스위치의 개방 고장이 발생 하면, 한상의 전류가 반주기 동안 나타나지 않기 때문에 출력 직류전압의 리플로 나타나게 된다. 이경우 고장 감지 및 허용 운전을 하지 않으면, 전력 품질을 저하되며, 직류 링크 콘덴서의 수명이 감축되는 문제를 발생 시킨다. 제안된 기법은 추가적인 하드웨어 없이 간단한 모델 적응 제어 (Model Reference Adaptive System)을 이용하여, 고장된 스위치를 감지 하며, 고장난 스위치의 반대 스위치를 켜고 나머지 2상을 전류제어 하여 3상 전류를 평형상태로 만들어 출력 직류전압의 리플을 줄이는 허용운전을 제안한다. 본 논문은 6kW급 3상 PWM 정류기 시스템을 모의해석을 통해 제안된 기법의 타당성을 입증 하였다.

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Prediction of Chemical Composition of Pure Weld Metal in SAW

  • Kim Y.;Ryu D. H.;Kim J. S.;Lee B. Y.
    • International Journal of Korean Welding Society
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    • v.5 no.1
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    • pp.10-14
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    • 2005
  • An element of Pure Weld Metal(PWM) is important factor to understand the Flux's conduct in Submerged Arc Welding(SAW). To get the element of PWM, pile-up welding over than 10 layers have been used in the past. But, it took a long time to analyze the elements of PWM in this method. Therefore, in this study, instead of pile-up welding over than 10 layers, one pass bead welding is used to predict an element of PWM using mathematical formula which got to be derived. As a results that applied the formula, there was no differences between theoretical and experimental value except the element Mn and Si.

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Analysis and Design of Filter at AC Source of Sigle Phase PWM Converter (단상 PWM 컨버터의 전원측 필터의 해석 및 설계)

  • Kim, Hong-Sung;Lee, Seung-Yo;Kim, Han-Sung;Yu, Gwon-Jong;Song, Jin-Soo
    • Proceedings of the KIEE Conference
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    • 1994.07a
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    • pp.447-449
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    • 1994
  • This paper deals with the static characteristics of filters at the AC source in single phase PWM converter using hysterisis current control method. The filters are needed to reduce the current harmonics. In general, there are two kinds of filters which can be used for current controlled PWM converter. One is the low pass filter, the other is the resonant filter for a frequency. This paper designs these filters by analysing the characteristics. And these filters are compared through performance index such as harmonic reduction factor and the value of components which make up filters.

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Voltage Balancing Control of Input Voltage Source Employing Series-connected Capacitors in 7-level PWM Inverter (7-레벨 PWM 인버터의 직렬 커패시터 입력전원의 전압균형제어)

  • Kim, Jin-San;Kang, Feel-soon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.2
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    • pp.209-215
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    • 2018
  • This paper present a 7-level PWM inverter adopting voltage balancing control to series-connected input capacitors. The prior proposed 7-level PWM inverter consists of dc input source, three series-connected capacitors, two bidirectional switch modules, and an H-bridge. This circuit topology is useful to increase the number of output voltage levels, however it fails to generate 7-level in output voltage without consideration for voltage balancing among series-connected capacitors. Capacitor voltage imbalance is caused on the different period between charging and discharging of capacitor. To solve this problem, we uses the amplitude modulation of carrier wave, which is used to produce the center output voltage level. To verify the validity of the proposed control method, we carried out computer-aided simulation and experiments using a prototype.

Characteristic Analysis of Line-start Permanent Magnet Synchronous Motor considering PWM Inverter (PWM 인버터 전원을 고려한 유도기동형 영구자석 동기전동기의 특성 해석)

  • Ryu, Dong-Wan;Oh, Young-Jin;Lee, In-Woo;Choi, Tae-Sik
    • Proceedings of the KIEE Conference
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    • 2004.10a
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    • pp.37-39
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    • 2004
  • This study investigates the characteristic analysis of Line-start Permanent Magnet Synchronous Motor considering PWM Inverter. The effects of the PWM inverter on machine characteristic are analyzed by using direct co-simulation of Matlab Simulink and Flux2D. Validity of analysis method is confirmed by the analysis result of Sin-wave power Model.

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High-Speed Elevator Controlled by Voltage-Type PWM Inverter (전압형 PWM 인버터 제어 고속 엘리베이터 시스템)

  • Kim, Woon-Soo;Jang, Cheol-Ho;Lee, Jea-Pil;Kim, Jung-Ha;Eom, Yong-Gi;Song, Seung-Bong
    • Proceedings of the KIEE Conference
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    • 1992.07b
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    • pp.1206-1210
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    • 1992
  • To satisfy the requirements of a stable speed control, comfortable ride and precise landing in the high-speed elevator. The induction motor driving elevator is controlled by inverter using vector control method which calculates optimum torque to apply to the Induction motor. This paper describes the control system of high-speed elevator that consists of the voltage-type PWM converter with an unity input power factor and sinusoidal input current and the voltage-type PWM inverter with a precise speed control and sinusoidal output current. The test results of actual elevator are presented.

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DC-Link Capacitance Estimation using Support Vector Regression in AC/DC/AC PWM Converters (SVR을 이용한 AC/DC/AC PWM 컨버터의 직류링크 커패시턴스 추정)

  • Ahmed G. Abo-Khalil;Jang, Jeong-Ik;Lee, Dong-Choon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.1
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    • pp.81-87
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    • 2007
  • This paper proposes a new capacitance estimation scheme for a DC-link capacitor in a three-phase AC/DC/AC PWM converter. A controlled AC voltage with a lower frequency than the line frequency is injected into the DC-link voltage, which then causes AC power ripples at the DC side. By extracting the AC voltage and power components on the DC output side using digital filters, the capacitance can then be calculated using the Support Vector Regression (SVR). By training of SVR, a function which relates a given input (capacitor's power) and its corresponding output (capacitance value) can be derived. This function is used to predict outputs for given inputs that are not included in the training set. The proposed method does not require the information of DC-link current and can be simply implemented with only software and no additional hardware. Experimental results confirm that the estimation error is less than 0.16%.