• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.392-393
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• 2017

본 연구에서는 에너지 저장시스템인 ESS 에너지 분배에 관한 시스템을 설계 및 제작하고 성능을 평가하였다. ESS에 충전하는 방법은 현재 기존의 상용전원을 전지에 충전하는 방식과(연계형) 태양광 에너지를 이용한 방법(독립형)으로 나누어져 있다. 본 연구에서는 어느 한쪽을 선택해야하는 번거로움을 줄여 상용전원과 태양광을 동시에 충전할 수 있는 시스템으로 설계하였다. 이러한 방법은 날씨 및 기타 외부적 환경이 좋지 않을 경우 일반 상용전원(AC 220V)를 이용하며 외부적 환경이 좋을 때는 태양전지로 충전이 가능하도록 연계형과 독립형이 동시에 가능하도록 구성하였다. 또한 출력에서 기존의 AC 220V 출력뿐만 아니라 DC12V, 24V의 전압과 USB(5V)도 동시에 출력이 가능하게 설계하므로 필요한 전압을 외부의 인버터나 컨버터가 필요 없이 바로 사용할 수 있도록 배분하였다. 따라서 본 연구에서는 ESS의 전력을 효율적으로 배분하므로 효율성을 증가시키고 내부의 배터리를 보호하는 시스템을 구성하여 그 성능평가를 실시하였으며 실험결과 효율적으로 배분된 전력을 얻을 수 있음을 검증하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.6
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• pp.122-128
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• 2011

This paper proposes a new control scheme of lithium ion battery units based on single phase multi-level converter. In the DC/AC converter applications using battery storage system, it is necessary to control the balancing voltage of individual battery units for high efficiency utilization. Using the proposed control scheme, the DC/AC single phase converter system is applied. To verify the effectiveness of the proposed control scheme, computer simulation is accomplished. In the computer simulation, lithium-ion battery units and single phase multi-level converter system are modeled and carried out using Psim simulation program. It will be helpful for design and applications of energy storage system with lithium-ion battery.

• Journal of Power Electronics
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• v.14 no.5
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• pp.918-925
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• 2014

This study presents an extended boost single-phase qZ-source DC-AC inverter for a single-phase photovoltaic system. Unlike the previously proposed single-phase qZ-source and semi-qZ-source inverters that achieve the same output voltage as that of the traditional voltage-fed full-bridge inverter, the proposed inverter can obtain higher output than input voltage. The proposed inverter also shares a common ground between DC input voltage and AC output voltage. Thus, possible ground leakage current problem in non-isolated grid-tied inverters can be eliminated with the proposed inverter. A 120 W prototype inverter is built and tested to verify the performance of the proposed inverter.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.168-171
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• 2005

The conception of the passive lossless snubber with the simpler is presented. Thus a necessity condition of the passive lossless soft switching converter with the simplest topology is directed. A novel passive regenerative snubber called soft snubber applied to a hard switching converter is proposed. The passive snubber consists of a snubber inductor, two snubber rectifiers, and a snubber capacitor. The losses are reduced by inserting a snubber inductor in the series path of the rectifier during it's turn off. It is so simple that can make energy reset or capacitor discharged directly without producing any current circulation. To show the superiority of this converter is verified through the experiment with a 640W, 100kHz prototype converter.

• Journal of the Korean Solar Energy Society
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• v.23 no.2
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• pp.91-98
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• 2003

Experimental study for a porous aluminum heat dissipator/or heat sink made by casting method is conducted to evaluate the performance of the porous aluminum heat sinks. The parameters applied for the present study are the manufacturing method. various bonding materials for the bottom plate of heat sink, and their different material, pore size, etc.. The casting method for porous aluminum heat sink is suggested for the best performance of heat dissipation in this experiment. The bottom plate applied by melting aluminum is introduced and proved their excellent characteristics compared with brazing, soldering, and bonding methods. In the present experiment, aluminum with different conductivities, such as AC8A and pure aluminum, are tested and the pure aluminums with the higher conductivity than AC8A shows their improvement of the performance. And the proper dimensions related to the pore size and the height of porous aluminum heat sinks are proposed in the present study.

• Transactions of the Korean hydrogen and new energy society
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• v.11 no.4
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• pp.179-188
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• 2000

The anodic reaction of hydrogen/oxygen gas mixture at platinum or palladium electrode interfacing with a solid polymer electrolyte was investigated using AC impedance method. The impedance spectrum of the electrode reactions of the mixture depends on the gas composition, electrode roughness, the mode of electrochemical operation and the cell potential. For electrolysis mode of operation, the spectrum taken for the reaction on a rough platinum electrode for the gas mixture revealed clearly that the local anodic reduction of oxygen gas takes place concurrently with the anodic oxidation of hydrogen gas.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.103-107
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• 2002

A contact-less power supply system (CPS) allows electrical energy to supply to mobile consumers without any electrical or mechanical contact. CPS works in the same principle as a transformer, with the track litz cable forming the primary circuit and the pickup as the secondary. The track power supply generates the high frequency alternating current in the track cable. The captured AC magnetic field generated by the track conductors produces electrical energy in the pickup coil and the pickup rectifier converts the high frequency AC power to DC while regulating the power to the load. This paper presents the theoretical analysis, simulation and experiment리 results of the series-parallel resonant converter working as contact-less power supply system.

• Journal of Power Electronics
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• v.5 no.4
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• pp.247-256
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• 2005

In order to harvest power in an efficient manner from a micro piezoelectric (PZT) device for charging the battery of a remote system, a new AC/DC resonant pulse power converter is proposed. The proposed power converter has two stages in the power conversion process. The first stage includes N-type MOSFET full bridge rectifier. The second stage includes a boost converter having an N-type MOSFET and a P-type MOSFET. MOSFETs work in the $1^{st}$ or $3^{rd}$ quadrant region. A small inductor for the boost converter is assigned in order to make the size of the power converter as small as possible, which makes the on-interval of the MOSFET switch of the boost converter ultimately short. Due to this short on-interval, the parasitic junction capacitances of MOSFETs affect the performance of the power converter system. In this paper, the performance of the new converter is analytically and experimentally evaluated with consideration of the parasitic capacitance of switching devices.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1746-1752
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• 2014

This paper presents an application of proportional-resonant (PR) current controllers in modular multilevel converter-high voltage direct current (MMC-HVDC) system under unbalanced voltage conditions. The ac currents are transformed and controlled in the stationary reference frame (${\alpha}{\beta}$-frame). Thus, the complex analysis of the positive and negative sequence components in the synchronous rotating reference frame (dq-frame) is not necessary. With this control method, the ac currents are kept balanced and the dc-link voltage is constant under the unbalanced voltage fault conditions. The simulation results based on a detailed PSCAD/EMTDC model confirm the effectiveness of the proposed control method.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.486-487
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• 2012

In this paper, novel three-port active power decoupling (APD) method for applying 250[W] micro-inverter. This type using third port for active power decoupling stores the surplus energy and supplies sufficient energy to grid. Conventional decoupling circuit is applied in single phase grid connected micro-inverter especially single-stage configuration like flyback-type DC-AC inverter. In this passive power decoupling method, electrolytic capacitor with large capacitance is needed for decoupling from constant DC power and instantaneous AC power. However the decoupling capacitor is replaced with film capacitor by using APD, thus the overall system can achieve smaller size and long lifespan. Proposed three-port flyback inverter is verified by design and simulation.