• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.457-458
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• 2020

본 논문은 저전압 직류배전 (LVDC)이 도입된 공장 및 물류센터 등 에서 다수의 전동 지게차를 운용할 때, 효과적으로 충전할 수 있는 지게차 배터리 충전기를 제안하였다. 제안하는 충전기는 SiC 반도체 및 의도적으로 비대칭으로 설계한 공진 인덕터를 사용한 두 개의 위상천이 풀브릿지 컨버터로 구성된다. 이를 통하여 최대 200A급 고속 충전 및 다종의 배터리 규격 (48V, 80V) 대응과 함께 고효율, 고전력밀도를 달성 하였다.

• 전기학회논문지
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• 제62권6호
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• pp.762-766
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• 2013

Interest in Wireless Power Transmission (WPT) technology has been increasing worldwide recently. This trend is proved by commercialized products such as electric toothbrush, wireless razor, and wireless charger for mobile phone battery. Studies for enhancing the applicability of the technology have been continuously conducted. Currently the WPT technology is based on the technologies using microwave, inductively coupling, and magnetic resonance. In the meantime, development of the microwave-based WPT faces difficulty due to health hazards involved in the technology, and application of the WPT technology using inductively coupling is restricted by area due to the problem of transmission length. In comparison, the WPT technology using magnetic resonance draws attention in terms of efficiency and transmission length. In this study, the sending coil based on the WPT technology using magnetic resonance system was replaced with an HTS coil to enhance transmission efficiency. Since the HTS coil has a zero resistance, power transmission loss can be minimized. At the same time, size of the current density could be increased to 100 times or more than typical coils. In addition, through impedance matching of LC device, maximal resonance properties were induced and consequently, frequency selection quality characteristics or Q was enhanced. As a result, the WPT type using the HTS coil showed a longer transmission length and better transmission efficiency compared with the WPT type using typical coils.

• 전력전자학회논문지
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• 제20권4호
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• pp.375-387
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• 2015

This study investigates an economic and highly efficient power-converter topology and its modulation scheme for 60 kW rapid EV charger system. The target system is a three-phase three-switch buck-type rectifier topology. A new carrier-based PWM scheme, which is characterized by simple implementation using logic gates, is introduced in this paper. This PWM scheme replaces the diode rectifier equivalent switching state with an active switching state to produce the same effective current flowing path. As a result, the distortion of input current during the polarity reversal of capacitor line voltage can be mitigated. The proposed modulation technique is confirmed through simulation verification. The proposed modulation technique and its implementation scheme can expand the operation range of the three-phase three-switch buck-type rectifier with high-quality AC input and capacitor ripple current.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.280-282
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• 2005

This paper proposes a simple MPPT control scheme of a Current-Control-Loop Error system Based that can be obtains a lot of advantage to compare with another digital control method, P&O and IncCond algorithm, that is applied mostly a PV system. An existent method is needed an expensive processor such as DSP that calculated to change the measure power of a using current and voltage sensor at the once. Therefore, it is applied a small home power generation system that required many expenses. But, a proposed method is easy to solve the cost reduction and power unbalance problems that it is used by control scheme to limit error of a current control of common sensor. This proposed algorithm had verified through a simulation and an experiment on battery charger using PIC that is the microprocessor of a low price.

• 한국산업정보학회논문지
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• 제23권1호
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• pp.23-29
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• 2018

독립형 태양광(PV) 시스템은 몽골 유목민 목축업자들에게 가장 중요한 에너지발전 시스템 중 하나이다. 기본적으로 독립형 PV 시스템은 두 개의 DC-DC 컨버터를 사용한다. 이 시스템은 비용이 많이 들고, 사이즈가 커지기 때문에 다른 장소로 이동 할 때 큰 어려움이 있다. 본 논문에서는 배터리의 SOC 제어 와 최대전력추종제어가(MPPT) 결합된 제어 알고리즘을 제안한다. 배터리는 3단계(Bulk, Absorption, Float Charge)로 충 방전된다. 본 논문에서는 Bulk단계에서 MPPT제어 기반으로 충전되는 제어 알고리즘을 제안한다. 제안된 제어 알고리즘을 다양한 날씨 조건에 대해서 적용하였으며, PSIM 소프트웨어를 이용한 시뮬레이션을 통하여 그 효용성을 검증하였다. 본 논문에서 제안한 알고리즘은 몽골 유목민들의 농촌 생활에 필수적인 독립형 태양광 발전 시스템을 설계하는데 유용하게 사용될 것이다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.631-631
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• 2013

Battery has major drawbacks including its size and life expectancy, and environmental problem. As an alternative, energy harvesting is emerging as a potential solution to replace battery along with more energy-efficient IT devices. The idea of harnessing energy from our living environment is sustainable, semi-permanent, and eco-friendly. Also, unlike battery, energy harvester does not require much space to store energy. Therefore, energy harvesting can provide a better source of power for small, portable, and wireless devices. Among various ways of harvesting energy from our surroundings, triboelectricity is chosen due to its potential to be miniaturized, and efficient. Triboelectric effect occurs as two different materials with different polarity of charge separation come into contact through friction, and then become separated so that electric potential difference is achieved. In this research, such characteristic of triboelectricity is used as a way to convert ambient mechanical energy into electric energy.Series of recent researches have shown promising results that the triboelectric energy harvester can be simple and cost effective. However, sufficient electricity level required to operate mobile devices has not yet been achieved.In this research, our group focuses on the design and optimization of triboelectric energy harvesting device to enhance its output. By using maskless lithography to pattern Kapton film and silicon substrate, which is used as a mold for PDMS thin layer, and sputtering metal electrodes on each side, we fabricate and demonstrate different designs of triboelectric energy harvester that utilizes the contact electrification between a polymer thin film and a metal thin foil. In order to achieve optimized result, the output voltage and current are measured under diverse conditions, which include different surface structure and pattern, material, and the gap between layers.

• 전력전자학회논문지
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• 제23권4호
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• pp.256-264
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• 2018

This paper proposes a three-bridge LLC resonant converter with auxiliary switches for a wide output voltage control range. This converter can be controlled in two ways to achieve a wide controllable output voltage control range of $V_o$ to $3V_o$. The first control mechanism is achieved through the pulse width modulation (PM) of the auxiliary switches and primary switching devices, while the second control mechanism is achieved through the frequency modulation (FM) of the primary switching devices that are configured to operate in the full-bridge switching mode when the auxiliary switches are turned off. The feasibility of using the proposed converter is verified by the results of an experiment with a 2kW prototype.

• 한국산학기술학회논문지
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• 제11권8호
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• pp.2999-3004
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• 2010

LED는 다른 광원에 비해 동작수명이 길고, 친환경적이며, 에너지 효율이 높은 장점을 가지고 있다. 최근 LED 기술의 발전으로 인해 고휘도, 고용량의 LED가 개발됨에 따라, 표시장치에만 적용되던 LED를 조명장치에도 적용하는 기술이 확산되고 있다. 조명장치에 적용되는 파워 LED는 발열문제로 인한 소손을 막기 위해 구동전류를 일정한 전류값 이하로 제어할 필요성이 있다. 본 논문은 파워 LED의 구동전류를 설정된 값 이하로 제어하는 전류제 한 기능을 갖는 파워 LED 태양광 보안등 개발에 관한 연구이다. 태양광 발전에 의해 생산된 전력을 DC12[V] 축전지에 저장한 후, 야간에 승압형 DC-DC 컨버터를 통해 DC24[V]로 승압시켜 파워 LED로 공급한다. 태양광 보안등 제어기, 승압형 DC-DC 컨버터, 72[W]급 파워 LED 램프를 개발하여 동작을 확인하고 관련 데이터를 도출함으로써 제안된 시스템의 타당성을 입증하였다.

• 한국전자통신학회논문지
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• 제8권3호
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• pp.439-445
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• 2013

본 연구는 발전기와 충전기를 통합하여 필요에 따라서 용접기 또는 발전기로 사용할 수 있는 시스템에 관한 것이다. 구체적으로는, 발전기를 제어하는 제어장치와 다기능 용접기를 사용할 수 있도록 하는 선택 스위치로 구성된 하이브리드 용접기로써 그 기능은 발전기 전원을 충전지에 충전이 완료되면, 발전기는 자동 정지하도록 구성하는 부분과 Co2 MMA TIG MIG MAG 용접기를 모제와 용제에 따라서 공급하는 가스를 제어하도록 제안하였다. 이는 한 번에 한 가지 또는 두 가지 정도만을 선택하는 기존 용접기의 성능과 편리성을 개선하기 위해 전압, 고주파, 모터 그리고 가스 밸브를 제어하는 시스템을 구현하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.323-324
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• 2016

In this paper a high efficiency bidirectional resonant converterfor Vehicle-to-Grid applications (V2G) is proposed.The proposed converter has adopted an LC auxiliary circuit in the third winding of the transformer. With the proposed method full softswitching can be ensured in all switches over a wide range of loadsand the secondary ringing can be removed with no additional snubber or clamp circuitry.In addition, since the proposed resonant converter is able to operate at an almost constant resonant frequencyregardless of the load, CC/CV charge of the battery can be simply implemented with high efficiency. A 3.3 kW bidirectional converter for On-Board Charger of Electric Vehicle is implemented to verify the validity of the proposed method. The experimental results show the high efficiency characteristics of the proposed converter over the wide range of load in both charge and discharge mode. The maximum efficiency of the proposed system was 98.13 % at 2.3 kW during the constant voltage mode charge operation.