• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.13-14
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• 2010

본 논문에서는 경계 모드(Critical Mode) 플라이백 타입의 DC-AC 인버터에 인터리빙을 적용한 디지털 제어를 제안한다. 연속모드(CCM)나 불연속모드(DCM)와 달리 경계 모드의 경우 주파수가 가변되기 때문에 인터리빙으로 구현하기는 상당히 까다로운 측면이 있다. 또한 아날로그 제어기로 구현에 한계를 지니기 때문에 보다 간편한 구현을 위해 디지털 제어IC을 이용하여 구현하는 방법에 대해 기술한다. 본문에서 200W급 플라이백 타입의 DC-AC 인버터에 경계모드 인터리빙을 방법을 적용한 후 실험으로 검증한다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.1-3
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• 2019

본 논문은 연속적인 입력 전류와 낮은 스위치 전압 스트레스를 갖는 플라이백 컨버터를 제안한다. 보조 권선과 직류 차단 캐패시터를 사용하여 기존 플라이백 컨버터(CFB)의 불연속적인 입력 전류의 리플을 저감시킨다. 이를 통해 입력 전류의 di/dt를 감소시켜 낮은 EMI 특성을 갖도록 한다. 그 결과 입력 필터 크기를 줄일 수 있으며 낮은 실효 입력 전류 때문에 인공위성의 캐패시터 수명을 연장 시킬 수 있다. 또한, 하나의 스위치와 다이오드를 추가하여 스위치 전압 스트레스를 감소시킨다. 그러므로 제안 회로는 스위칭 손실이 작으며, 작은 온 저항($R_{ds(on)}$)을 갖는 스위치 적용이 가능하여 도통 손실을 저감시켰다. 본 논문에서는 제안 회로의 모드 분석과 이론적인 분석을 제시한다. 제안 회로는 현재 인공위성에 사용하는 입출력 사양인 입력 전압 50 V, 출력 전압 15V, 출력 전력 100W의 사양으로 시뮬레이션을 진행하였다. 이 결과를 통해 제안 회로의 타당성을 증명한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.42-48
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• 2016

In this paper, a high-precision peak detector circuit that detects the output voltage information of a fly-back converter is proposed. The proposed design consists of basic analog elements with only one operational amplifier and three transistors. Because of its simple structure, the proposed circuit can minimize the delay time of the detection process, which has a strong impact on the precision of the regulation aspect of the fly-back converter. Furthermore, by using an amplifier and several transistors, the proposed detector can be fully integrated on-chip, instead of using discrete circuit elements, such as capacitors and diodes, as in conventional designs, which reduces the production cost of the fly-back converter module. In order to verify the performance of the proposed scheme, the peak detector was simulated and implemented by using a 0.35 m MagnaChip process. The gained results from the simulation with a sinusoidal stimulus signal show a very small detection error in the range of 0.3~3.1%, which is much lower than other reported detecting circuits. The measured results from the fabricated chip confirm the simulation results. As a result, the proposed peak detector is recommended for designs of high-performance fly-back converters in order to improve the poor regulation aspect seen in conventional designs.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.225-226
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• 2016

통상적으로, 기존 단상 AC 전원용 플라이백 컨버터는 75W 이상의 조건에서 역률개선회로를 채용하게 된다. 이에 따라 2-Stage 형태의 회로를 구성해야 하기 때문에, 회로의 부품 수 증가 및 전력 효율을 낮추는 단점이 동반된다. 또한, 다수의 자성소자(인덕터, 트랜스포머) 사용이 필수적이며, 이는 회로의 부피 및 원가 상승의 주요한 원인이 된다. 본 논문에서는 역률 개선 기능을 가진 밸리필 플라이백 컨버터의 실용적 설계 및 구현 방안을 제시한다. 더불어, 밸리필 정류기의 전해 커패시터 Short 시 방폭 문제를 해결하기 위한 OVP(Over Voltage Protection) 회로의 실용적 설계 방법을 제시하여 제안 회로의 양산 가능성을 증명한다. 본 논문에서는 제안 회로의 이론적 특성을 분석하고, 78W 급 플라이백 컨버터 시작품의 실험적 분석을 통해 그 타당성을 검증한다.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.720-725
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• 1991

In this thesis, the lead-lag compensator is designed to improve output characteristics of flyback zero voltage switching quasi-resonant converters. The switch and the diode are assumed ideally. And the SMPS is modelled by state equations with four operation modes. And the model for controller design is also achived by using a state space averaging method, which is continuous time average of state variables every period. The lag, the lead and the lead-lag compensator is designed the SMPS respectively. The time domain analysis and the frequency domain analysis are done for each compensated circuit. It is possible increasing the phase margin and improving the transient response by the compensators. The phase lag compensator has small overshoot comparatively. But the bandwidth is narrower than the others, so it has longest settling time. For the phase lead compensator, the response come to steady-state within short period. But the overshoot is the largest due to its large peak gain. Finally, the phase lead-lag compensator has medium characteristics in the overshoot and the settling time.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.1
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• pp.20-26
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• 2002

HID(high intensity discharge)lamps include high pressure mercury lamp, high pressure sodium lamp and metal halide lamp. Metal halide lamps have been considered to be one of the most erective light sources. These lamps have good efficiency, good color rendering and good focusing capability. The objective of this research is to alum on the metal halide lamp(MH70W) by the developed electronic ballast with free voltage input(AC 100∼277V). The developed electronic ballast consists of a free voltage input converter, a flyback converter ＆ half-bridge inverter, ignitor ＆ protector and control1er. Experimental results show that developed electronic ballast turns on the metal halide lamp(MH70W) with free voltage input(AC 100∼277V) very well.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1341-1350
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• 2017

In this paper, a high reliability 30W DC-DC converter is designed considering military standard (MIL-STD) for military applications such as guided weapon and aircraft. The performances and specifications of conventional military grade DC-DC converter are practically analyzed. The requirements for military grade DC-DC converter are established in consideration of MIL-STD and analysis results of conventional product. Two isolated DC-DC converter, forward and fly-back converter, are designed and compared to determine topology. From experimental results under various operating conditions, the forward topology satisfied performances and specifications of MIL-STD for military DC-DC converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.91-98
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• 1999

An integrated ZCS quasi-resonant converter(QRC) for the power factor correction with a single switch is presented in this paper. The power factor correction can be achieved by the discontinuous conduction mode(DCM) operation of the input current. The proposed converter gives the good power factor, low line current harmonics, and tight output regulation. The input current waveform of the prototype designed using design equations shows about 15% of total harmonic distortion at rated condition. Also, the efficiency and power factor can be obtained about 86% and 0.985, respectively, at rated condition. The proposed converter is suitable for a low power level converter with a tightly regulated low output voltage and switching frequency of more than several hundreds kHz.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.551-555
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• 2004

The two-transformer full bridge (TTFB) PWM converter has two transformers which act as the output inductor as well as the main transformer, i.e. as the forward and the flyback transformer. Although the doubled leakage inductor of the TTFB makes it easier to achieve the zero-voltage switching (ZVS) of the lagging leg switch along the wide load range, it instigates a serious voltage ringing in the secondary rectifier diodes, which would require the dissipative snubber circuit, cause the serious power dissipation, and increase the voltage stress across those diodes. To overcome these problems, a, new lossless diode-clamp rectifier (LDCR) is employed as the output rectifier, which helps the voltage across rectifier diodes to be clamped on a half the output voltage $(V_o/2)$ or the output voltage $(V_o)$. Therefore, no dissipative snubber for rectifier diodes is needed and a high efficiency as well as low noise output voltage can be realized. The operations, analysis and design consideration of proposed converter are presented in this paper. To verify the validity of the proposed converter, experimental results from a 425W, 385-170Vdc prototype for the plasma display panel (PDP) sustaining power module (PSPM) are presented.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.499-501
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• 2008

본 논문은 공진요소를 포함한 고전압 플라이백 컨버터의 설계 절차를 제시하는 것으로써, 고압 플라이백 컨버터 설계 시 기존 플라이백 컨버터의 Power Stage 설계 식을 적용하였을 때 원하는 출력 전압을 얻지 못한다. 고전압을 발생시키기 위한 고전압 플라이백 변압기는 2차 측의 많은 권선수와 높은 전압 때문에 기생 커패시턴스(parasitic capacitance)가 매우 크고, 과도상태에서 컨버터 전류 및 전압의 기생 공진(parasitic resonance)이 심각하게 발생한다. 이러한 공진요소를 고려하여 고전압 플라이백 컨버터의 특성을 해석하고 설계 절차를 제시한다. 이를 통해 고전압 플라이백 컨버터의 소형화 및 경량화를 도모하고, 고압 전원장치의 기술 축적을 위해 연구되었다. 제안된 회로의 동작원리를 설명하고, 타당성을 실험을 통하여 검증한다.