• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.397-399
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• 1994

In this parer, the development of input power factor and the harmonic distortion of line current were showed in the proposed three phase AC-DC converter. We identified that DC voltage in the output terminal has fast dynamic response and has nearly ripple. Moreover, the converter also possesses the regenerative capability which is useful for many applications. The switching frequency of this converter operated with constant in the range of 2KHZ. Finally, simulation and experiment results are presented.

• 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.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 추계학술대회 논문집
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• pp.327-331
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• 2008

The problems of power factor and harmonics are occurred in converter system which used to SCRs and diodes as power semiconductor devices IGBT was solved that problem, maintain the input line current with sinusoidal wave current of input power source voltage. In this paper, three phase AC to DC boost converter that operates with unity power factor and sinusoidal input currents is presented. The current control of the converter is based on the space vector PWM strategy with fixed switching frequency and the input current tracks the reference current within one sampling time interval. Space vector PWM strategy for current control was materialized as a digital control method. By using this control strategy low ripples in the output voltage, low harmonics in the input current and fast dynamic responses are achieved with a small capacitance in the dc link.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1226-1228
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• 2004

A novel lossless passive snubber is proposed for soft switching the boost type converters. The proposed snubber does not use any auxiliary switches. but uses two identical snubber capacitors which are charged in parallel at turn off of the main switch and discharged in series at turn on automatically, and the discharged energy is recovered effectively (more than $95[\%]$ recovery) into the output capacitor. Thus, the snubber provides zero voltage switching for the converter main switch, reducing both the turn off losses and the electromagnetic interference(EMI) noise, whitch improves the converter performance. The experimental results of a 20[kHz] 600[W] DC-DC boost converter and a single-phase AC-DC boost rectifier with the new snubber are presented.

• Journal of Power Electronics
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• 제17권4호
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• pp.1071-1087
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• 2017

This paper introduces a DC/AC converter, which can be connected in parallel with a diode rectifier for regenerative applications. The DC/AC converter is supposed to transmit regenerative energy to the power grid when a motor is braking. Isolation transformers are not needed in the topology, which can reduce the size and cost. An analysis of the zero-order current existing in the system is carried out. In addition, algorithms to minimize the zero-order current, control the power factor and keep the DC bus voltage stable are discussed. A 55kW industrial prototype is built to verify the proposed analysis and control strategies.

• 전력전자학회논문지
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• 제27권5호
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• pp.397-401
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• 2022

The construction of the ITER tokamak machine is ongoing at a 77% process rate to achieve the first plasma in 2025. The 18 sets of power supply systems comprising 400 MVA thyristor AC/DC converters for the superconducting magnets supplied by Korea (KO) are being installed with other systems, such as PF converters (China), DC busbars (Russia), and cooling water systems (India), in two buildings (Europe). The system interfaces have been defined during the design stage, and the systems have been manufactured. However, during the on-site installation work, several installation and integration issues emerged due to the manufacturing tolerance and design mistakes. To continue the installation and testing, the engineers of each system resolved the interface issues, planned the commissioning, and integrated the test plan. This paper describes the on-site installation status and issues and the commissioning plan of KO AC/DC converters.

• 전력전자학회논문지
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• 제8권6호
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• pp.551-560
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• 2003

본 논문은 5KW급의 SOFC와 저전압 배터리를 복합전원으로 하는 10KW급 독립형 연료전지발전시스템의 전력변환장치의 개발에 관한 것이다. 이를 위한 전격변환장치는 연료전지로부터의 저전압을 상승시키기 위한 고주파 DC-DC 컨버터 및 이를 안정된 교류전원으로 변환하기 위한 DC-AC 인버터 그리고 저전압 배터리를 충$.$방전하기 위한 양방향 DC-DC 컨버터로 구성된다. 미국 에너지부 및 IEEE가 주최한 "2003 International Future Energy Challenge Competition"에서 제시한 90%이상의 효율과 $40/KW 이하의 양산가등의 사양을 목표로 개발된 본 전력변환장치에 대한 토폴로지, 주요 부품의 설계 및 제어방식에 관하여 기술하고 실험결과를 제시한다.험결과를 제시한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 추계학술대회
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• pp.186-187
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• 2010

최근 직류 출력을 갖는 분산전원 시스템의 증가와 높은 에너지 변환효율을 갖는 직류(DC) 배전 시스템에 대한 관심이 증가하고 있다. 직류(DC) 배전을 빌딩에 적용하기 위해서는 계통연계형 AC/DC 컨버터가 필수적이다. 빌딩용 직류(DC)배전 시스템에서는 다양한 부하들이 상시 대용량의 AC/DC 컨버터에 연결되어 있기 때문에 컨버터의 기동시 과도상태를 최소화한 안정적인 DC전압 확보가 필수적이다. 본 논문에서는 외부 파라미터 변화나 외란에 대한 강인한 성능을 가지는 슬라이딩 모드 제어기를 사용하여 3상 AC/DC 컨버터의 초기 운전 시 발생할 수 있는 DC전압의 오버슈트 저감을 시뮬레이션에 의해 검증하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 추계학술대회
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• pp.148-149
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• 2019

Voltage unbalance can be occured in AC-DC microgrid systems when AC loads or AC systems are connected. To solve this problem, 3-phase 4-wire interlinking converter is used. This paper proposes in PLL method that can detect accurate phase and voltage magnitude.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1364-1367
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• 2005

In this paper, a novel prototype topology of soft switching PWM controlled high frequency AC power conversion circuit without DC voltage smoothing chemical capacitor filter link from the voltage grid of utility frequency AC power supply source with 60Hz-100V or 60Hz-200V is proposed and introduced for innovative consumer induction heating(IH) boiler applications as hot water producer, steamer and super heated vapor steamer.