• Journal of Power Electronics
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• v.16 no.5
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• pp.1669-1677
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• 2016

A new auxiliary circuit for boost, buck, buck-boost, Cuk, SEPIC, and zeta converters is introduced to provide soft switching for pulse-width modulation converters. In the aforementioned family of DC-DC converters, the main and auxiliary switches turn on under zero current transition (ZCT) and turn off with zero voltage and current transition (ZVZCT). All diodes commutate under soft switching conditions. On the basis of the proposed converter family, the boost topology is analyzed, and its operating modes are presented. The validity of the theoretical analysis is justified by the experimental results of a 100W, 100 kHz prototype. The conducted electromagnetic emissions of the proposed boost converter are measured and found to be lower than those of another ZCT boost converter.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.171-173
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• 2009

최근 LED 기술의 발달로 LED의 이용범위가 점차 넓어지고 있다. 이러한 LED를 구동하기 위한 시스템의 저비용 고효율을 위해서는 입력전압에 대한 출력전압의 승강압이 중요하다. 따라서 본 논문에서는 승강압이 가능한 DC-DC 컨버터인 Buck-Boost, ZETA, SEPIC 토폴로지를 적용하여 LED Lamp 구동 시스템을 구성해 본다. 위 세 가지의 컨버터는 입력전압에 대하여 출력전압의 승강압이 가능하고 입출력 전압특성이 동일하다. 그러므로 각각의 컨버터들을 이용하여 LED driving 회로를 구성하고, Pspice 시뮬레이션을 통해 나타나는 입출력 효율을 측정하여 승강압용 DC-DC 컨버터의 특성을 비교한다.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.325-326
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• 2015

본 논문에서는 입력 직류링크 전해 캐패시터와 power factor correction(PFC) 회로 없이 고효율과 고역률을 갖는 단일 전력 변환 직렬 공진형 AC-DC 컨버터를 제안한다. 제안된 컨버터의 1차측은 절연형 single-ended primary-inductor converter(SEPIC) 컨버터와 스위치의 서지 전압을 최소화하고 영전압스위칭을 위한 능동 클램프 회로로 구성되어 있다. 2차측은 큰전압 이득을 위한 배전압 회로로 구성되어 있으며 직렬 공진을 이용하여 다이오드의 영전류 스위칭을 달성함으로써 역방향 회복 문제를 해결 할 수 있다. 또한 별도의 PFC 회로와 입력 직류링크 전해 캐패시터 없이 제안된 역률개선 제어 알고리즘을 이용하여 간단한 구조로 고역률을 달성할 수 있다. 본 논문에서는 제안된 회로의 이론적 해석 및 시작품의 실험을 수행하여 타당성을 검증하였다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.343-344
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• 2012

In high power PV generation system, the solar cell normally generates wide output voltage depending on the insolation, cell's temperature and shade effect. This paper will propose a high efficiency converter allowing the wide input voltage to supply stable voltage with the controller and operation for the PV generation system. The proposed converter consists of two stages comprising SEPIC with a coupled inductor and LLC, which generates 24 V of output at the final output terminal. In this paper, a design method and experimental results with a test-bed of 50 W will be presented to validate the proposed converter.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.117-118
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• 2016

본 논문은 입력 전류 리플이 없고 낮은 스위치 전압 스트레스를 갖는 고승압 부스트-세픽 DC-DC 컨버터를 제안한다. 제안된 컨버터는 부스트 단의 보조회로에 의해 입력 전류 리플이 상당히 제거되었으며 세픽 단에 결합 인덕터를 적용하여 높은 전압 이득을 달성하였다. 또한 스위치 전압 스트레스는 클램핑 회로에 의해 감소되었으며 따라서 상대적으로 낮은 $R_{ds(on)}$ 갖는 MOSFET을 사용하여 컨버터의 효율이 개선되었다. 추가적으로 결합 인덕터의 누설 인덕터로 인하여 출력 다이오드의 역회복 손실이 완화되었다. 제안된 컨버터는 이론적 해석과 200[V]-200[W]하드웨어 시작품을 제작하여 검증하였다.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.5
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• pp.455-461
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• 2015

This paper deals with an experimental verification of a temperature-dependent power loss model of a DC/DC converter in severe temperature conditions. The power loss of a DC/DC converter is obtained by summing the losses by the components constituting the converter including switching elements, diodes, inductors, and capacitors. MIL-STD-810F stipulates that any electronic devices must be operable in the temperature ranging from $-50^{\circ}C$ to $70^{\circ}C$. We summarized the temperature-dependent loss models for the converter components. A SEPIC-type converter is designed and built as a target. Using a constant-temperature chamber, a test rig is set up to measure the power loss of the converter. The experimental results confirm the validity of the loss model within 4.5% error. The model can be useful to predict the efficiency of the converter at the operating temperature, and to provide guidelines in order to improve the efficiency.

• Journal of Power Electronics
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• v.15 no.2
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• pp.309-318
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• 2015

This study proposes a dual-output single-stage bridgeless single-ended primary-inductor converter (DOSSBS) that can completely remove the front-end full-bridge alternating current-direct current rectifier to accomplish power factor correction for universal line input. Without the need for bridge diodes, the proposed converter has the advantages of low component count and simple structure, and can thus significantly reduce power loss. DOSSBS has two uncommon output ports to provide different voltage levels to loads, instead of using two separate power factor correctors or multi-stage configurations in a single stage. Therefore, this proposed converter is cost-effective and compact. A magnetically coupled inductor is introduced in DOSSBS to replace two separate inductors to decrease volume and cost. Energy stored in the leakage inductance of the coupled inductor can be completely recycled. In each line cycle, the two active switches in DOSSBS are operated in either high-frequency pulse-width modulation pattern or low-frequency rectifying mode for switching loss reduction. A prototype for dealing with an $85-265V_{rms}$ universal line is designed, analyzed, and built. Practical measurements demonstrate the feasibility and functionality of the proposed converter.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.2
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• pp.97-104
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• 2017

In the present industrial field, the demand for the development of the solar power source device and the charging device for the solar cell is gradually increasing. The solar charger is largely divided into a DC-DC converter that converts the voltage generated from the sunlight to a charging voltage, and a battery and a charger that are charged with an actual battery. The conventional charger topology is used either as a Buck converter or a Boost converter alone, which has the disadvantage that the battery can not always be charged to the desired maximum power as input and output conditions change. Although studies using a topology capable of boosting and stepping have been carried out, Buck-Boost converters or Sepic converters with relatively low efficiency have been used. In this paper, we propose a new Buck Boost combination power converter topology structure that can use Buck converter and Boost converter at the same time to improve inductor current ripple and power converter efficiency caused by wide voltage control range like solar charger.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.3
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• pp.224-230
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• 2016

In this study, a single-power-conversion series-resonant ac-dc converter with high efficiency and high power factor is proposed. The proposed ac-dc converter consists of single-ended primary-inductor converter with an active-clamp circuit and a voltage doubler with series-resonant circuit. The active-clamp circuit clamps the surge voltage and provides zero-voltage switching of the main switch. The series-resonant circuit consists of leakage inductance $L_{lk}$ of the transformer and resonant capacitors $ C_{r1}$ and $ C_{r2}$. This circuit also provides zero-current switching of output diodes $D_1$ and $D_2$. Thus, the switching loss of switches and reverse-recovery loss of output diodes are considerably reduced. The proposed ac-dc converter also achieves high power factor using the proposed control algorithm without the addition of a power factor correction circuit and a dc-link electrolytic capacitor. A detailed theoretical analysis and the experimental results for a 1kW prototype are discussed.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.3
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• pp.205-210
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• 1986

A soil micromorphological study of clayey terrace soils in Yeongnam area was carried out to investigate the soil genetic features and to distinguish the soil parent materials. Dominant plasmic fabrics in the terrace soils were vosepic, mosepic, insepic, and masepic of sepic fabrics but the Geugrag and Upyeong in Yeongil sequence have an asepic fabrics. Embedded grain cutans in the terrace soils were characterized by having porphyroskelic related distribution. Among pedological features of the B horizons of the terrace soils, the argillic cutans of ferriargillans and glaebules of manganiferrous concretions were the dominant in mineralogical composition, and the papules are abundant in the most terrace soils indicating that the soils are generally old. The substrata of the Bancheon in Yeongcheon and Upyeong in Yeongil area were so different from the terrace deposits in plasmic fabrics that these soils were believed to be composed of bisequum profiles. Because of having the free grain cutans, it was considered that the substrata of Bancheon in Yeongcheon and Upyeong in Yeongil area might have a period of soil formation before deposition of the terrace materials.