• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.4
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• pp.250-254
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• 2016

Currently, power conversion system which converts AC to DC Power is applied in domestic urban railway. The diode rectifier is used in most of them. However the diode rectifier can not control the output voltage and can not regenerate power as well. On the other hand, PWM (pulse width modulation) converter using IGBT (isolated gate bipolar transistor) can control output voltage, allowing it to reduce the output voltage drop. Moreover the Bi-directional conduction regenerates power which does not require additional device for power regeneration control. This paper compared the simulation results for the DC power supply system on both the diode rectifier and the PWM converter. Under the same load condition, simulation circuit for each power supply system was constructed with the PSIM (performance simulation and modeling tool) software. The load condition was set according to the resistance value of the currently operating impedance of light rail line, and the line impedance was set according to the distance of each substations. The train was set using a passive resistor. PI (proportional integral) controller was applied to regulate the output voltage. PSIM simulation was conducted to verify that the PWM Converter was more efficient than the diode rectifier in DC Traction power supply system.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.243-245
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• 1994

A PWM forced-commutated converter with DC voltage source is studied in this paper. This PWM-VSC using spacs vector modulation permits to control bi-directional power exchange between the AC mains and the DC source. The principle of the active and reactive power control is presented. In transient operation, the analysis of reactive component current is performed. Finally, the simulation results are also presented and discussed.

• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.44-45
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• 2016

본 논문에서는 DC Nano-grid를 위한 25kW급 고효율 양방향 컨버터를 개발하였다. 제안하는 양방향 컨버터는 넓은 입력전압 범위를 만족하기 위하여 Cascade 부스트-벅 컨버터의 구조로 하였으며 상용화된 SiC MosFET기반 3레그 IPM을 최적으로 사용하기 위해 2상 인터리빙 부스트 컨버터와 단상 벅 컨버터로 하였다. 또한 승 강압 모드에 따라 스위칭하는 스위치 개수를 감소시켜 스위칭 손실을 최소화 하였다. 25kW 시작품을 통해 14kW에서 효율 98.9%를 달성하였다.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.5-6
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• 2011

최근 환경 문제와 에너지 자원 고갈 등의 이유로 전력 사용에 있어서 효율이 매우 중요시 되고 있다. 이와 맞물려 기존의 교류배전에 비해 직류배전이 가지는 효율적 이점이 주목받으면서 직류 배전에 대한 연구가 활발히 이루어 지고 있다. 본 연구에서는 직류배전 적용시 이용 가능한 양방향 AC/DC 전력 변환기의 경부하 효율 향상을 위해 새로운 skip-cycle mode를 개발하고 이를 디지털 제어를 이용하여 구현하였다. 풀브릿지 타입의 3.3kW 양방향 전력변환기를 이용하였다.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.259-260
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• 2014

본 논문에서는 모듈화된 두 직류 마이크로그리드를 직류 버스 레벨에서 양방향 DC-DC 컨버터로 연계한 새로운 시스템을 제안한다. 연계 컨버터로 인해 모듈 간 직접적인 전력 전송이 가능하므로 전체 시스템의 효율이 향상되고 한 모듈의 교류 전원 연결 사고 시 빠른 대처 및 복구가 가능하다. 이로 인해 제안하는 시스템은 다수의 모듈화된 직류 배전 시스템으로 구성되는 데이터 센터 등에 적용할 수 있다. 제안하는 시스템 모델과 운영 방안은 시뮬레이션을 통해 검증하였다.

• Journal of Korea Multimedia Society
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• v.9 no.12
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• pp.1669-1680
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• 2006

This paper explains that the RF systems for hi-directional wireless capsule endoscopes were designed and implemented. The designed RF systems for a capsule endoscope can transmit the images of intestines from the inside to the outside of a body and the behavior of the capsules can be controlled by an external controller simultaneously. The hi-directional wireless capsule endoscope consists of a CMOS image sensor, FPGA, LED, battery, DC to DC Converter, transmitter, receiver, and antennas. The transmitter and receiver which were used in the hi-directional capsule endoscope, were designed and fabricated with $10mm(diameter){\times}3.2mm(thickness)$ dimensions taking into the MPE, power consumption, system size, signal to noise ratio and modulation method. The RF systems designed and implemented for the hi-directional wireless capsule endoscopes system were verified by in-vivo experiments. As a result, the RF systems for the hi-directional wireless capsule endoscopes satisfied the design specifications.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.323-324
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• 2013

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charge mode, constant-current mode, and constant-voltage mode. The pre-charge mode employs the stair-case shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is specified to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 78A. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.6-8
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• 2010

HEV(Hybrid Electrical Vehicle)의 배터리와 전동기/발전기용 인버터 사이에 전력의 흐름에 따라 바뀌어 동작하는 양방향 컨버터가 장착된다. 이 컨버터는 낮은 배터리의 전압을 승압해 DC-Link 전압을 높혀줌으로써 전동기의 전류용량을 낮춰 줄 수 있으며 그에 따른 전동기의 부피를 감소시키고 손실을 줄이는 역할을 한다. 본 논문에서는 HEV에서 사용되는 양방향 컨버터의 모드 절환을 포함한 디지털 제어 방법을 소개하고, 시뮬레이션을 통해 검증하였다.

• Journal of Power Electronics
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• v.7 no.4
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• pp.343-352
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• 2007

This paper proposes a modularized charge equalization converter for hybrid electric vehicle (HEV) lithium-ion battery cells, in which the intra-module and the inter-module equalizer are Implemented. Considering the high voltage HEV battery pack, over approximately 300V, the proposed equalization circuit modularizes the entire $M^*N$ cells; in other words, M modules in the string and N cells in each module. With this modularization, low voltage stress on all the electronic devices, below roughly 64V, can be obtained. In the intra-module equalization, a current-fed DC/DC converter with cell selection switches is employed. By conducting these selection switches, concentrated charging of the specific under charged cells can be performed. On the other hand, the inter-module equalizer makes use of a voltage-fed DC/DC converter for bi-directional equalization. In the proposed circuit, these two converters can share the MOSFET switch so that low cost and small size can be achieved. In addition, the absence of any additional reset circuitry in the inter-module equalizer allows for further size reduction, concurrently conducting the multiple cell selection switches allows for shorter equalization time, and employing the optimal power rating design rule allows fur high power density to be obtained. Experimental results of an implemented prototype show that the proposed equalization scheme has the promised cell balancing performance for the 7Ah HEV lithium-ion battery string while maintaining low voltage stress, low cost, small size, and short equalization time.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.63-73
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• 2022

The differential power processor (DPP) system is used to prevent a decrease in the total power generation due to the partial shading of photovoltaic modules. Compared with traditional series strings and full power processing (FPP) converter solutions, the DPP converter system shows advantages in terms of modularization process, volume, and transformation losses. However, the system has a limitation in that the power generation process of differential power processors produces lower power under certain irradiation conditions. This paper proposes a structure and operating algorithm for differential power processing modules that can use a single power converter for multiple strings. The operational algorithm for the differential power regulators allows the maximum power generation to be maintained in comparison with conventional series-connected and differential power processing methods even under various partial shading conditions. The operation algorithm of the proposed DPP is verified by Matlab/Simulink simulations.