• Journal of the Korean Society for Railway
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• v.14 no.5
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• pp.411-415
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• 2011

DC/DC switching power converters are commonly used to generate a regulated DC output voltages with high efficiencies from different DC input sources. The voltage mode DC/DC converter utilizes MOSFET (metal-oxide semiconductor field effect transistor), inductor, and a PWM (pulse-width modulation) controller with oscillator, amplifier, and comparator, etc. to efficiently transfer energy from the input to the output at periodic intervals. The fundamental boost converter and a buck converter containing a switched-mode power supply are studied. In this paper, the electrical characteristics of DC/DC power converters are simulated by program of SPICE, and the PWM controller is implemented to check the operation. In addition, power efficiency is analyzed based on the specification of each component.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.1
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• pp.1-10
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• 2016

Drivers for LED MR16 retrofit lamps need to be compatible with the dimmers and electronic transformers which originally operated with the halogen lamps to be replaced. We present a two-stage MR16 LED driver consisting of a boost converter in the first stage and a buck converter in the second stage. Our design has been analyzed in the frequency domain using simulations to demonstrate that it effectively suppresses the high-frequency components of the AC output of the electronic transformer. Experiment results with a driver prototype verify the simulation results as well as dimmability.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.109-112
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• 1988

All parasitics such as switch conduction voltages, conduction resistances, switching times and ESR''s of capacitors are counted in the new state-space modeling based on non-ideal switching functions. An equivalent simplified model is derived from the complex circuit with parasitics. Hence the results are very simple and exact, which are very important features of modelings. The pole frequency, dc voltage gain, and efficiency of the general converter, the buck-boost converter are analyzed and verified by the experiments with good agreements with the theories. This may be a good summary for the previous works concerned with parasitics.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.2
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• pp.134-139
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• 2017

In this study, an inductive power transfer (IPT) charger for electric vehicles is proposed to improve the entire system efficiency and power density by eliminating the DC-DC converter in the secondary side. In the proposed IPT charger, the DC-link voltage is adjusted according to the coupling coefficient through cascade buck-boost converter in the front-end side, and the bridgeless rectifier performs the charging of battery. The control algorithm for the proposed IPT system is theoretically explained, and the validity of the proposed system is verified by informative simulation.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.423-424
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• 2014

본 논문에서는 배터리 충 방전을 위한 새로운 고승압 양방향 DC-DC 컨버터를 제안한다. 제안 회로는 하나의 회로로 양방향 스위치가 가능하게 하였다. 기존 DC-DC 컨버터는 고주파 스위칭 동작 시 손실분 저항의 증가로 승압이 어려운 문제점이 있다. 이를 위해 기존 Boost converter 회로 방식보다 승압비가 높은 회로를 제안하였다. 그리고 기존 충전회로는 10배 이상의 입 출력 강압변환 시, 낮은 duty cycle로 소자 스트레스가 높아 고 사양의 소자를 사용해야 했다. 제안회로는 충전 시, Buck converter 동작을 하면서 기존 duty cycle 보다 3배가량 높아 소자 스트레스를 줄였다. 이를 모의실험 및 실험을 통해 타당성을 검증하였다.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.850-852
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• 1993

A buck-boost zero current switched(ZCS) series resonant AC to DC converter for the DC output voltage regulation together with high power factor is proposed. A dynamic model for this AC to DC converter is developed and an analysis for the internal operational characteristics is explored. With the proposed control technique, the unity power factor and the DC output voltage regulation without a current overshoot can be obtained.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1543-1544
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• 2005

고효율과 경량의 전자식 단권변압기를 적력전자 기술을 적용하여 구성하여 보았다. 이 system은 양 방향으로 전력, 전류변환이 가능한 4사분면의 어느 동작도 가능하도록 하기위하여 양방향으로 도통이 가능한 스위치를 이용하여 구성하였다. 이 전체적 구성은 Buck Converter와 Boost Converter를 동시에 응용한 회로로 구성 하였다. 이 컨버터는 전류의 진상과 지상이 심한 유도성 부하와 용량성의 부하에도 잘 적응할 수 있고, 더 나아가 에너지 반환하는 교류시스템에도 적용할 수 있다. 본 연구에서 제시하는 시스템은 자기회로를 자화시키는 여자전류와 전류가 흐르는 도체가 가지는 동손을 감소킬 수 있다. 이에 반하여 반도체 스위치가 가지는 스위칭 손실과 반도체 회로를 구동하는데 필요한 구동회오의 유지에 필요한 전력이 필요하다. 이러한 여러 요인의 증가하여도 전체 손실은 자장결합 변압기보다 작은 것 을 보여주고 있다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.356-357
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• 2019

본 논문에서는 넓은 충전 전압 범위와 V2G 기능을 갖는 급속 충전기용 DC-DC 컨버터를 제안한다. 제안한 컨버터는 SRC(Series Resonant Converter)와 2상 Buck/Boost 컨버터로 구성된 2-stage 구조로써 넓은 충전 전압 범위에 적합하며, 배터리 충전뿐만 아닌 V2G(Vehicle to Grid) 동작이 가능하다. 또한 2상 인터리빙 방식을 사용함으로써 전류 분담을 통해 소자의 전류 정격 및 출력 필터 사이즈를 낮출 수 있다. 제안하는 컨버터의 시작품 실험을 통해 타당성을 검증하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.111-121
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• 2014

A bi-directional DC-DC converter has been developed for a wireless power transceiver which enables a device to receive and transmit power wireless. Generally, the wireless power transceiver requires two DC-DC covnerter and two external inductors. However, the proposed wireless power transceiver requires only one DC-DC converter and one inductor, allowing small form-factor. The bi-directional DC-DC converter implemented in $0.35{\mu}m$ BCDMOS process operates as a buck converter at the wireless power receiving mode and the power efficiency is 91% when the ouput power is 3W. In the wireless power transmitter mode, the DC-DC converter operates as a boost converter. With the bi-directional DC-DC converter and the proposed efficiency maximizing techniques, the power efficiency of wireless power transceiver is 81.7% in receiver mode and 76.5% in transmitter mode.

• Journal of Power Electronics
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• v.17 no.2
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• pp.334-345
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• 2017

In order to meet the increasing needs of the hybrid energy source system for electric vehicles, which demand bidirectional power flow capability with a wide-voltage-conversion range, a bidirectional three-level DC-DC converter and some control strategies for hybrid energy source electric vehicles are proposed. The proposed topology is synthesized from Buck and Boost three-level DC-DC topologies with a high voltage-gain and non-extreme duty cycles, and the bidirectional operation principle is analyzed. In addition, the inductor current ripple can be effectively reduced within the permitted duty cycle range by the coordinated control between the current fluctuation reduction and the non-extreme duty cycles. Furthermore, benefitting from duty cycle disturbance control, series-connected capacitor voltages can also be well balanced, even with the discrepant rise and fall time of power switches and the somewhat unequal capacitances of series-connected capacitors. Finally, experiment results of the bidirectional operations are given to verify the validity and feasibility of the proposed converter and control strategies. It is shown to be suitable for hybrid energy source electric vehicles.