• 한국산업융합학회 논문집
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• 제20권2호
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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.

• Journal of Power Electronics
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• 제19권2호
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• pp.431-442
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• 2019

This paper proposes a unified high-frequency bipolar buck-boost (UHFBB) control strategy for a dual-active-bridge (DAB), which is derived from the classical buck and boost DC/DC converter. It can achieve optimized current stress of the switches and soft switching in wider range. The UHFBB control strategy includes multi-control-variables, which can be achieved according to an algorithm derived from an accurate mathematical model. The design method for the parameters, such as the transformer turns ratio and the inductance, are shown. The current stress of the switches is analyzed for selecting an optimal inductor. The analysis is verified by the experimental results within a 500W prototype.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권3호
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• pp.300-312
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• 2014

A single-inductor multiple-output (SIMO) DC-DC converter providing buck and boost outputs with a new switching sequence is presented. In the proposed switching sequence, which does not require any additional blocks, input energy is delivered to outputs continuously by flowing current through the inductor, which leads to high conversion efficiency regardless of the balance between the buck and boost output loads. Furthermore, instead of multiple output loop compensation, only the freewheeling current feedback loop is compensated, which minimizes the number of off-chip components and nullifies the need for the equivalent series resistance (ESR) of the output capacitor for loop compensation. Therefore, power conversion efficiency and output voltage ripples can be improved and minimized, respectively. Implemented in a 0.35-${\mu}m$ CMOS, the proposed SIMO DC-DC converter achieves high conversion efficiency regardless of the load balance between the two outputs with maximum efficiency reaching up to 82% under heavy loads.

• 전력전자학회논문지
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• 제9권5호
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• pp.478-484
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• 2004

본 논문에서는 두 개의 무손실 스너버 셀을 제안하여 고주파에서 동작할 수 있는 컨버터를 일반화하였다. 컨버터 구현 시 스너버 셀의 선택은 컨버터 구조에 따라서 결정된다. 스너버 셀의 구성은 한 개의 포화 인덕터와 LC 공진회로, 두 개의 다이오드로 구성된다. 인덕터는 컨버터 주 다이오드의 역회복 손실을 저감시키는 역할을 하는데 포화 인덕터를 사용하면 셀 내의 공진 에너지를 감소시켜 컨버터가 고주파에서 동작될 수 있는 특성을 갖는다. 컨버터의 일반화는 무손실 스너버 셀을 벅(Buck), 부스트(Boost), 벅-부스트(Busk-Boost), 척(Cuk), 제타(ZETA) 및 세픽(SEPIC)에 추가하여 실현하였다. 제안된 컨버터의 고주파 동작 및 고효율 특성은 400 kHz, 125 W 부하에서 실험하여 기존의 PWM 컨버터에 비하여 고효율로 동작함을 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.226-239
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• 2018

In this paper, design and control method ZVT Interleaved Bidirectional LDC(IB-LDC) for mild-hybrid electric vehicle is proposed. The IB-LDC is composed of interleaved buck and boost converters employing an auxiliary inductor and auxiliary capacitors to achieve zero-voltage-transition. Operating principle of IB-LDC according to operation mode is introduced and mathematically analyzed in buck and boost mode. Moreover, PFM and phase control are proposed to reduce circulating current for low power range. Passive components design such as main inductor, auxiliary inductor and capacitors is suggested, considering ZVT condition and maximizing efficiency. Furthermore, a 600W prototype of ZVT IB-LDC for MHEVs is built and tested to verify validity.

• Journal of Power Electronics
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• 제19권1호
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• pp.11-23
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• 2019

In this study, a novel zero voltage zero current transition (ZVZCT) bidirectional DC-DC converter is proposed by employing coupled inductors. This converter can turn the main switch on at ZVZCT and it can turn it off with zero voltage switching (ZVS) for both the boost and buck modes. These characteristics are obtained by using a simple auxiliary sub-circuit regardless of the power flow direction. In the boost mode, the auxiliary switch achieves zero current switching (ZCS) turn-on and ZVS turn off. Due to the coupling inductors, this converter can make further efficiency improvements because the resonant energy in the capacitor or inductor can be transferred to the load. The main diode operates with ZVT turn-on and ZCS turn-off in the boost mode. For the buck mode, there is a releasing circuit to conduct the currents generated by the magnetic flux leakage to the output. The auxiliary switch turns on with ZCS and it turns off with ZVT. The main diode also turns on with ZVT and turns off with ZCS. The design method and operation principles of the converter are discussed. A 500 W experimental prototype has been built and verified by experimental results.

• 전력전자학회논문지
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• 제12권6호
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• pp.465-471
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• 2007

본 논문에서는 새로운 소프트 스위칭형 PFC 벅-부스트 AC-DC 컨버터에 대해 연구된다. 제안된 컨버터에 사용된 제어스위치의 턴-온과 턴-오프는 부분공진 동작에 의해 소프트 스위칭으로 되어 스위칭 손실을 줄이고, 입력전류는 듀티율 일정제어에 의한 교류 입력전압의 크기에 비례된 불연속적 유사 펄스열의 정현파 형태를 가진다. 그 결과 컨버터는 효율이 증대되고 입력역률이 증대되는 효과를 가진다. 또한 제안된 컨버터의 출력전압은 제어스위치의 PWM 제어에 의해 조정되고 벅-부스트용 인덕터에 흐르는 전류는 불연속모드로 제어되어 제어회로와 제어기법이 간단한 장점이 주어진다. 제안된 PFC 벅-부스트 컨버터는 기존의 PFC 벅-부스트 컨버터와 비교되어 해석되고 컴퓨터 시뮬레이션과 실험을 통해 그 해석적 타당성이 입증된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.151-154
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• 1988

Quantum converters, a subset of resonant converters operating with optimal conditions are modeled. It is shown that series resonant converter(SRC) can be modeled as buck/boost converter with an equivalent inductor and parallel resonant converter(PRC) can be modeled as Cuk converter, with an equivalent capacitor. Also new resonant circuits with boost, buck-boost and Cuk converter characteristics are proposed. From these models, the quantum converters can be designed to be controlled with closed loop feedback, having many advantages such as low device switching stress, reliable high frequency operation and low EMI.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권6호
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• pp.291-297
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• 2003

This paper presents a current-source-inverter based on a buck-boost configuration and its application for residential photovoltaic system. The proposed circuit has five switches. Among them, only one switch acts as chopping, and the other determine the polarity of output; therefore, it can reduce the switching loss. Because the input inductor current is operated on the discontinuous conduction mode, high power factor can be achieved without additional input current controller. So the overall system shows a simple structure. The operational modes are analysed in depth, and then it was verified through the experimental results using a 150 [W] prototype equipped with digital signal processor TMS320F241.

• Journal of Electrical Engineering and Technology
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• 제5권3호
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• pp.477-483
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• 2010

This paper is studied on a novel buck-boost isolated converter for high efficiency and high power factor. The switching devices in the proposed converter are operated by soft switching technique using a new quasi-resonant circuit, and are driven with discontinuous conduction mode (DCM) according to pulse width modulation (PWM). The quasi-resonant circuit makes use of a step up-down inductor and a loss-less snubber capacitor. The proposed converter with DCM also simplifies the requirement of control circuit and reduces a number of control components. The input ac current waveform in the proposed converter becomes a quasi sinusoidal waveform in proportion to the magnitude of input ac voltage under constant switching frequency. As a result, it is obtained by the proposed converter that the switching power losses are low, the efficiency of the converter is high, and the input power factor is nearly unity. The validity of analytical results is confirmed by some simulation results on computer and experimental results.