• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1845-1849
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• 2010

We have proposed and fabricated a Buck-Boost DC to DC Converter for Thermoelectric generator (TEG) with constant output voltage suitable for battery chargers or constant voltage supplies in the range of several watt. The experimental and simulation results have shown that the proposed method allows stable operation with maximum 86% power transfer efficiency. The proposed circuit has a merit in cost and miniaturization of a system compared to conventional MPPT algorithms, because the proposed method adopts only analog circuit without DSP or micro controller unit for calculating peak power point by iterative methods.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.311-313
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• 2008

본 논문에서는 연료전지를 위한 독립형 3kW급 인버터 시스템을 제안한다. 논문에 사용된 연료전지는 26V에서 46V의 가변적인 출력을 가지므로 220V의 교류전압으로 변환하기 위해서 높은 변압비를 가지는 DC/DC 컨버터로에서 400V의 DC링크 전압으로 승압되고 최종적으로 DC/AC 인버터를 통해서 220V의 교류전압으로 변환된다. 또한 DC/DC 컨버터의 직류출력전압을 저장하여 연료전지 초기구동과 제어기 전원에 공급함으로써 독립적인 시스템으로써 동작할 수 있다. 본 논문에서 제안한 시스템은 각 부분별 시뮬레이션을 통해서 검증하였다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.529-530
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• 2006

An efficient sensing scheme adoptable in DC-DC converter is described. The output voltage of the whole DC-DC converter is fed back to the input voltage of the sensor. The comparison in the sensor is accomplished by a current push-pull action. With a fixed reference, the comparator can be embodied based on (W/L) ratios. The current-mode scheme benefits the system better than a conventional voltage-mode one in terms of small area, low power consumption.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.116-121
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• 2012

DC/DC switching power converters produce DC output voltages from different DC input sources. The converter is used in regenerative braking of DC motors to return energy back in the supply, resulting in energy savings for the systems containing frequent stops. The DC/DC converter is composed of a PWM-IC (pulse width modulation integrated circuit) controller, a MOSFET (metal-oxide semi-conductor field-effect transistor), an inductor, capacitors, and resistors, etc. PWM is applied to control and regulate the total output voltage. In this paper, radiation shows the main influence on the changes in the electrical characteristics of comparator, operational amplifier, etc. in PWM-IC. In the PWM-IC operation, the missing pulses, the changes in pulse width, and the changes of the output waveform are studied by the simulation program with integrated circuit emphasis (SPICE) and compared with experiments.

• Journal of IKEEE
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• v.24 no.2
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• pp.586-591
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• 2020

An interleaved current-fed high step-up DC-DC converter is proposed. Besides high voltage gain, a low ripple input current is achieved by adopting interleaving operation. Moreover, soft-switching characteristic of the proposed converter reduces switching losses of active power switches and raise the conversion efficiency. The reverse-recovery problem of output rectifiers is also alleviated by controlling the current changing rates of diodes by utilizing the leakage inductances of transformers. Experimental results obtained on a 200W prototype are discussed.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.337-338
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• 2012

본 논문에서는 전 영역 ZVS가 가능한 양방향 3상 절연형 인터리브드 DC-DC 컨버터의 제어방법에 대해 서술한다. 3상 절연형 인터리브드 DC-DC 컨버터는 모든 스위치가 ZVS동작을 하여 높은 효율을 갖고 3상 구조를 채택하여 전류경로의 분산을 통한 전력전달 능력의 증대 효과 및 입력전류 리플 크기를 줄여주는 인터리브드 효과를 갖는다. 승압/강압 능력이 있는 부스트/벅 컨버터의 구조는 낮은 권선비의 변압기로 높은 승압/강압 전력변환, 에너지원과 부하 사이에 절연이 가능한 구조이며, 인터리브 동작이 이루어짐에도 불구하고 3상을 각각 제어하지 않고 배터리의 전압전류와 출력전압만을 입력받아 벅모드와 부스트 모드 모두 전압, 전류제어를 수행함으로서 시스템의 간략화가 가능하였다. 따라서 본 논문에서는 제안된 DC-DC컨버터의 제어기를 구성하고 실험을 통해 확인하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.665-667
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• 2010

In this paper, the method to detect the IM(Inter Modulation) components of power amplifier is proposed by using frequency down-convertor. Output signals of power amplifier which is coupled by 20dB coupler and divided by power divider are applied to RF and LO of the frequency converter. It could be found the magnitude of IM components of power amplifier as a converted DC voltage which is come from the difference between 3th and 5th IM component. The detected DC voltage values are changed from 0.72V to 0.9V when 3rd IM component level changed from -26.4dBm to +2.15dBm and 5th IM component level changed from -34.2dBm to -12.89dBm as the Vgs of 3W power amplifier is changed.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.477-483
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• 2011

Existing switching system that is one of the ways which are used for DC/DC power converter is classified to hard-switching system and resonant-soft-switching system, generally. Hard-switching system is inefficient because the power loss of the switching element is large when it is been to trun on or turn off. And resonant-soft-switching system have the defect that need to add the another reactor and capacitor that make it expensive and huge. This paper suggest the ZVS Full-Bridge power converter contrcution of novel switching system for the overcoming these shortcomings. In Suggested soft-switching system, the front of buck converter at diode current, switch is changing on and off at the part of full-bridge converter's zero voltage part. as the result that is possible to be ZVS excepting the reactor and capacitor. also to verify the reasonability of the isolated ZVS full-bridge DC/DC converter as previously suggested, we produced the 500[W] level DC/DC converter and enforced the simulation for Psim, and then it able to conform the superiority of the DC/DC converter's efficient.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.777-783
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• 2009

In this paper, we implemented a wireless power transmission system at 2.45 GHz. The transmission power is limited within 20 dBm according to the ISM frequency regulations. We used two zero-bias Schottky diode and optimized the RF-DC converter for working a clock at 80 cm distance using a receiver with a single antenna and an Rf-DC converter to reduce parts and cost compared to previously reported literatures.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.2
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• pp.235-240
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• 2010

In order to substitute incandescent lamps, a power supply device for 7W class LED lamps which are environmentally friendly and energy saving is designed LED lamps consist of a multitude of chip LED connected in parallel and series. 11ms it is necessary to supply LED lamps with DC voltage and current. However, when LED lamps are in use, they are connected directly to AC 220V. This is why we need to have AC/DC, DC/DC power converters including a control system of voltage and current. For this, a transformerless and simple LED lamp driver is designed 조ich can control the current and output voltage for LED string of LED lamp.