• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.202-204
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• 2003

This paper introduces a new algorithm to calculate distortion power using complx THD(Total Harmonic Distortion) index. The proposed algorithm involves FFT(Fast Fourier Transform) to compute real and imaginary THDs of voltage and current. Case studies are presented to show the availability of the proposed method.

• Journal of Power Electronics
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• 제15권1호
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• pp.96-105
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• 2015

In recent years, the multilevel converters have been given more attention due to their modularity, reliability, failure management and multi stepped output waveform with less total harmonic distortion. This paper presents a novel symmetric multilevel inverter topology with reduced switching components to generate a high quality stepped sinusoidal voltage waveform. The series and parallel combinations of switches in the proposed topology reduce the total number of conducting switches in each level of output voltages. In addition, a comparison between the proposed topology with another topology from the literature is presented. To verify the proposed topology, the computer based simulation model is developed using MATLAB/Simulink and experimentally with a prototype model results are then compared.

• 조명전기설비학회논문지
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• 제27권9호
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• pp.36-43
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• 2013

The prevalence of electronic devices in our modern life is accompanied with the generation of harmonics caused by the nonlinear characteristic load. Especially, the employment of LED have brought the rapid use of SMPS. SMPS is used for supplying the constant DC electric power to the LED display board, but it has a big problem which gives birth of harmonics causing by its high-speed switching. measurement HIOKI 3196 equipment to solve these harmonics were measured. In this study, we are LED Display Board Load Measuring the impedance response with $X_L$ changes for removing harmonics in the measured. And we adopted the suitable passive filter by the impedance response characteristic obtained in the $X_L$ variation experiments. We are trying to deeply the application of passive harmonic filter characteristics that generation in the LED Display Board through EDSA LED simulation.

• 한국통신학회논문지
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• 제21권5호
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• pp.1325-1331
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• 1996

본 논문에서는 전류 스위칭(switched-current:SI) 시스템에서 THD(total harmonic distortion) 증가 원인인 클럭피드스루(clock feedthrough:CFT) 오차 전압을 감소시키는 새로운 전류 메모리(current-memory) 회로를 제안하였다. 제안한 전류 메모리는 CMOS 상보형의 PMOS 트랜지스터를 이용하여 CFT 오차 전압에 의한 출력 왜곡 전류를 감소시킨다. 제안한 전류 메모리 회로를 $1.2{\mu}{\textrm{m}}$ CMOS 공정을 사용하여 설계하고, 입력으로 전류 크기 $68{\mu}{\textrm{m}}$인 1MHz 정현파 신호를 인가하였다.(샘플링 주파수:20MHz) 모의 실험 결과, 기존의 전류 메모리보다 CFT 오차 전압에 의한 출력 왜곡 전류가 10배 정도 감소를 나타내었으며 신호 대 바이어스 전류비가 0.5(peak signal-to-bias current ratio:i/J)인 1KHz 신호를 인가할 경우 THD는 -57dB이다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권11호
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• pp.671-679
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• 2004

This paper presents the on-line current controller tuning method of grid-connected inverter using PSO(particle swarm optimization) technique for minimizing the harmonic current. Synchronous frame PI current regulator is commonly used in most distributed generation. However, due to the source voltage distortion, specially in weak AC power system, current may contain large harmonic components, which increase THD(total harmonic distortion) and deteriorates power quality. Therefore, some tuning method is necessary to improve response of current controller. This paper used the PSO technique to tune the current regulator and through simulation and experiments, usefulness of the tuning method has been verified. Especially in simulating the tuning process, ASM(average switching model) of inverter is used to shorten execution time.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.205-207
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• 2005

In this paper, the Point of Common Coupling (PCC) is selected to analyze harmonic characteristic of distribution system by IEC 61000 - 3 - 6 in Electromagnetic Compatibility(EMC). Harmonic voltage and current were measured at the PCC of real distribution system. Harmonic distribution, nonlinear load component and Total Harmonic Distortion(THD) were verified by measurement. The effective and accurate modelling of real distribution system were proved through a analysis of harmonic impedance, voltage and current in steady-state. Harmonic transfer characteristic in distribution system were summarized and investigated through a analysis of harmonic voltage and harmonic current in harmonic current source.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.138-145
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• 2015

In this paper, a novel static overmodulation scheme (OVM) for space-vector PWM (SVPWM) is proposed. The proposed static OVM scheme uses the concept of adding offset voltages in linear region as well as overmodulation region to fully utilize DC-link voltage. By employing zero sequence voltage injection, the proposed scheme reduces procedures for achieving SVPWM such as complicated gating time calculation. In addition, this paper proposes a stepwise discontinuous angle movement in high modulation region in order to reduce Total Harmonic Distortion (THD). The validity of the proposed scheme is verified through theoretical analysis and experimental results.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권4호
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• pp.448-456
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• 2012

This paper presents a multilevel inverter configuration which is designed by insertion of a bidirectional switch between capacitive voltage sources and a conventional H-bridge module. The modified inverter can produce a better sinusoidal waveform by increasing the number of output voltage levels. By serial connection of two modified H-bridge modules, it is possible to produce 9 output voltage levels including zero. There are 24 basic switching patterns with the 9 output voltage levels. Among the patterns, we select the 2 most efficient switching patterns to get a lower switching loss and minimum dv/dt stress. We then analyze characteristics of Total Harmonic Distortion (THD) of the output voltage with variation of input voltage by computer-aided simulations and experiments.

• 전력전자학회논문지
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• 제4권1호
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• pp.82-90
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• 1999

본 논문은 단일 스위치 3상 ZCS 강압형 정류기의 펄스주파수 제어기법을 다루고 있다. 제안하는 펄스주파수 제어방법은 거의 정현적인 입력전류를 흐르게 하여 3상 강압형 정류기의 성능을 보여준다. 제안하는 제어구조의 유용성을 검증해 주는 시뮬레이션과 실험 결과는 단일 스위치 3상 ZCS 강압형 정류기의 고역율, 입력전류의 낮은 THD, 부하 변동에 대한 전압의 응답특성들이 뛰어남을 보여준다.

• Journal of Power Electronics
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• 제16권4호
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• pp.1407-1414
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• 2016

Unlike existing pulse-width modulation (PWM) techniques, such as sinusoidal PWM and random PWM, the wavelet PWM (WPWM) technique based on a Harr wavelet function can achieve a high fundamental component for the output voltage, low total harmonic distortion, and simple digital implementation. However, the original WPWM method lacks output voltage control. Thus, the practical application of the WPWM technique is limited. This study proposes an improved WPWM technique that can regulate output voltage amplitude with the addition of a parameter. The relationship between the additional parameter and the output voltage amplitude is analyzed in detail. Experimental results verify that the improved WPWM exhibits output voltage control in addition to all the merits of the WPWM technique.