• 전력전자학회논문지
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• 제10권4호
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• pp.339-346
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• 2005

본 논문에서는 3-레그 2상 인버터의 새로운 PWM방식을 제안하였다. 기존의 3-레그 인버터의 PWM방식은 전형적인 SVPWM 방식을 적용하여 PWM 방식이 복잡하다. 3-레그 2상 인버터를 "중성점이 있는 4-레그 인버터"의 등가회로라고 할 때 3-레그 인버터에서 형성되는 6개의 섹터는 4개의 섹터로 축소되며, 각 영역에서는 SYPWM 방식 대신 단순화된 정현파형 PWM방식을 적용할 수 있다. 각 레그의 스위치마다 스위칭 시간을 계산하는 스위칭 패턴을 제시하였다. 제안된 ,3-레그 인버터의 PWM방식에 대한 타당성을 확인하기 위해 모의 실험과 실험이 실행되었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.308-312
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• 2003

The objective of this paper is to investigate the power spectrum of a three-phase and a two-phase RCD (Random Pulse Centered Displacement) PWM scheme. The two-phase or three-phase pulses of RCD-PWM scheme are mutually center-aligned as in SVM(Space Vector Modulation), but the common pulse center is displaced randomly from the middle of the period. To verify the validity of the proposed two-phase RCD-PWM scheme, the power spectra of the output voltage, the d.c link current in the inverter drives and the radiated acoustic noise are experimentally investigated. And, the performance of the proposed two-phase RCD-PWM scheme was compared and discussed with the conventional three-phase RCD-PWM scheme.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.328-335
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• 1999

Three phase full bridge rectifier has been used to obtain dc voltage from three phase ac voltage source. The rectifier system has drawbacks that power factor is low and power flow is unidirectional. Therefore, when dc voltage increases due to regeneration of power the dynamic resister for dissipation of regeneration power must be installed. But three phase PWM converter can be controlled to operate with unity power factor and bidirectional power flow. Therefore when the PWM converter is used as do supply system, the dissipating resistor is not necessary. On this thesis, in order to design a controller having good performance, the hee phase PWM converter is completely modeled by using circuit DQ-transformation and thus a general and simple instructive equivalent circuit is obtained; the inductor set becomes a second order gyrator-coupled system and three phase inverter becomes a transformer as well. Under given phase angle(${\alpha}$) and modulation index(MI) of the three phase inverter, the dc and ac characteristics are obtained by analysis of the transformed equivalent circuit The validity of the equivalent circuit is confirmed through PSPICE simulation. And based on the dc and ac characteristics a controller with unity power factor is proposed.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권4호
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• pp.472-476
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• 2012

In this paper, a sensorless control scheme for a three-phase bi-directional voltage-type PWM rectifier in wind power generation system that operates without the input AC voltage sensors (generator side) is described. The basic principles and classification of the PWM rectifier are analyzed, and then the three-phase mathematical model of the input AC voltage sensorless PWM rectifier control system is established. The proposed scheme has been developed in order to lower the cost of the three-phase PWM rectifier but still achieve excellent output voltage regulation, limited current harmonic content, and unity input power factor.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.414-416
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• 2005

In this paper, a new scheme of current programmed control for three phase PWM AC-AC converter is presented. By considering only the magnitude components, a similar scheme in the DC-DC converter can be extended to the three phase PWM AC-AC converter. The proposed current programmed control will be well adopted into various converter topologies though three phase PWM AC-AC boost converter is treated as an example. The converter analysis is carried out by applying the vector DQ transformation to obtain physical insight into the converter operation. Finally, the experiment result shows the validity of the proposed scheme.

• 한국산학기술학회논문지
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• 제17권4호
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• pp.26-33
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• 2016

최근 UPS의 효율을 높이기 위하여 무변압기형 UPS의 사용이 증가되고 있다. 하지만 무변압기형 UPS는 입 출력 구조상 문제로 인해 3상4선식의 IGBT PWM 정류기가 필요하며 이는 기존의 3상3선식 PWM 정류기의 PFC 제어기법으로는 중성선 전류 문제로 동작이 되지 않으므로 3상4선식 PWM 정류기의 특성에 맞는 적절한 PWM 제어기법이 요구되고 있다. 3상4선식 IGBT PWM 정류기의 제어를 위한 제어기법으로는 각상 개별제어 기법과 3D SVM 기법이 있지만 두 방식 모두 장단점이 존재한다. 각상 개별제어 기법은 제어가 불안정하고 3D SVM 기법은 입력 측 인덕터의 L값이 상당히 커져야하는 문제점을 가지고 있다. 따라서 본 논문에서는 기존의 각상 개별제어 방식과 d-q 제어 알고리즘을 접목시켜 동기좌표계상에서 직류로 제어하는 3상4선식 IGBT PWM 정류기 제어기법을 제안하였다. 또한 본 논문에서 제안한 3상4선식 IGBT의 PWM 정류기 제어 알고리즘을 바탕으로 시뮬레이션과 실험을 수행 하였다. 시뮬레이션을 수행한 결과, 3상4선식 IGBT PWM 정류기를 안정적으로 제어하고 중성선 전류를 줄일 수 있어, 본 논문에서 제안한 방식의 유효성을 확인하였다.

• Journal of Power Electronics
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• 제8권4호
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• pp.363-370
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• 2008

In this paper, three kinds of PWM strategies for a three-phase current-fed dc/dc converter are proposed and compared in terms of losses and voltage transfer ratio. Each PWM strategy is described graphically and their switching losses are analyzed. With the proposed PWM C strategy, one turn-off switching of each bridge switch is eliminated to reduce switching losses under the same switching frequency. In addition, RMS current through the bridge switches is lowered by using parallel connection between two bridge switches and thus, conduction losses of the switches are reduced. Further, copper losses of the transformer are decreased due to the reduced RMS current of each transformer's winding. Therefore, total losses are minimized and the efficiency of the converter is improved by using the proposed PWM C strategy. Digital signal processor (DSP: TI320LF2407) and a field-programmable gate array (FPGA: EPM7128) board are used to generate PWM patterns for three-phase bridge and clamp MOSFETs. A 500W prototype converter is built and its experimental results verify the validity of the proposed PWM strategies.

• 수산해양기술연구
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• 제28권3호
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• pp.274-285
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• 1992

Among various Power converters, a variable voltage variable frequency (VVVF) three-phase PWM inverter is regarded as most promising power converter due to its capabilities, which permits the control of voltage, frequency and harmonic contents in a single power stage employing only on DC source. As a modulating technique of the PWM inverter, the regular sampling technique has rendered possible the on-line computation and generation of PWM control waveforms with a reasonably high switching frequencies. In this paper, microprocessor based three-phase regular samping PWM inverter with real-time control algorithm and control circuits for driving three phase AC motor has been developed. Harmocic components of PWM waveform were analized theoretically in terms of Bessel function series and then calculated by digital computer and observed with spectrum analyzer.

• 전기학회논문지P
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• 제66권2호
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• pp.58-62
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• 2017

This paper presents a novel prototype of the resonant AC link snubber circuit for the three-phase sinwave soft-switching PWM inverter. In principle, its operating principle is described, and the performance evaluations of the specific instantaneous space voltage modulated three-phase sinewave soft switching PWM inverter incorporating a resonant AC link snubber is illustrated, and evaluated, introducing the specific space voltage vector modulation implementation. It is conferred that the validity of three-phase soft-switching inverter treated here in setup experiment.

• 전력전자학회논문지
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• 제7권3호
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• pp.224-236
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• 2002

PWM기법의 성능을 비교하고 있다. 랜덤 펄스 위치 PWM기법은 2상 또는 3상 펄스들을 변조 구간내의 임의의 위치에 랜덤하게 배치하고 인버터 스위칭에 의하여 고조파의 스펙트럼을 광역화하는 RPWM기법이다. 시뮬레이션과 실험에 의하여 인버터 출력 전압의 고조파 스펙트럼과 맥동 전류 파형 그리고 모터의 가청 스위칭 소음의 저감 효과를 비교 검토하였다. 스위칭 손실 및 연산시간 그리고 구현의 용이성에서 3상 RPWM보다는 2상 RPWM이 양호하며, 고조파의 광대역화 측면에서는 3상 RPWM이 보다 좋은 성능을 지니고 있음을 알 수 있었다. 또한 가청 스위칭 소음저감은 2상 RPWM과 3상 RPWM이 거의 유사한 성능을 갖고 있음이 확인되었다.