• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.257-260
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• 2002

In this paper, the circuit of AC Choppers for $CO_2$laser Power Supply are proposed and investigated. IGBT-controlled ac voltage regulators, operating at high frequency chopping mode. Chopping-to-supply duty ratio plays an important role in terms of laser output. Laser input energy is varied by controlling the leakage transfomer used with the proposed system. This improved circuit employs a 3 electrode-type and Ring Blower. This improved circuit system has many advantages compared with the conventional SMPS such as simple design requirment, easy implementation, high reliability, low switching loss, and consequently high efficiency. As a result, the maximun output was 16W at duty-ratio of 92%, total gas mixture of $CO_2$: $N_2$: He = 1 : 9 : 15, total pressure of 15torr.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.993-997
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• 1998

This paper presents a two-switch boost chopper with a sinewave current shaping and power factor correction scheme, which is applied for driving electronic ballast using high frequency resonant inverter. A working principle of the proposed one-converter type electronic ballast with power factor correction and active filtering schemes is described on the bases of the equivalent circuit of each operation mode, together with operation analysis. The steady-state performance evaluations of this electronic ballast are illustrated and discussed in experiment.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.593-597
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• 2002

The power conversion system for Fuel Cell Electric Vehicle(FCEV), technical trend, and a various type of Fuel Cell and its characteristics are presented. Especially, this paper is focused on the control methods of power conversion devices applied for the Fuel Cell Electric Vehicle, configuration of power system and operation mode of the bidirectional DC/DC converter. The prevalent topology for the power conversion systems, simulation results and development a tendency of FCEV and it's market investigations are introduced.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.750-753
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• 2002

A novel single-stage half-bridge high frequency resonant inverter using ZVS(Zero Voltage Switching) with high input power factor suitable for induction heating applications is presented in this paper. The proposed high frequency resonant Inverter integrates half-bridge boost rectifier as power factor corrector(PFC) and half-bridge resonant inverter into a single stage. The input stage of the half-bridge boost rectifier is working in discontinuous conduction mode (DCM) with constant duty cycle and variable switching frequency. Simulation results through the Pspice have demonstrated the feasibility of the proposed inverter. This proposed inverter will be able to be practically used as a power supply in various fields as induction heating applications, DC-DC converter etc.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.639-643
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• 2003

We are interested in this paper on the control of an electromechanical system consisting of a doubly-fed induction generator(DFIG), driven by a prime mover that can supply or extract mechanical power, e.g., a flywheel inertia, and an induction motor(IM). The stator of the Induction machine is connected to the stator of the generator whose rotor voltage is regulated by a bidirectional converter. The main interest of this configuration is that it permits a bidirectional power flow between the motor, which may operate in regenerative mode, and the generator We propose a passivity-based controller to regulate the motor mechanical speed. Since this kind of controllers achieve stabilization via energy balancing, regulation of the power flow in the system is naturally incorporated. Simulation results are presented to illustrate the main points of our paper.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.410-411
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• 2010

풀 브릿지 컨버터는 1차 측과 2차 측이 트랜스포머를 통하여 절연되어 있으며, 이 트랜스포머에 교번으로 전압을 걸어주어 1주기에 2번의 전력을 전달한다. 이러한 전력 전달 과정에서 트랜스포머에 흐르는 자화 전류에 오프셋이 발생할 수 있으며, 이는 효율 감소 및 소자의 파괴를 야기할 수 있으므로 제거하는 것이 바람직하다. 디지털 개발 환경에서 트랜스포머의 자화 전류 오프셋을 줄이고 동특성의 개선을 위하여 예측 제어 방식을 사용한 최대 전류 제어 방식을 제안하고 실험을 통하여 동작을 검증한다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.3
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• pp.109-114
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• 2002

This paper analysis the transient performance of the modified excitation system using 4-quadrant chopper for a synchronous machine connected to HVDC system. Conventionally, capacitors are used to supply reactive power requirement at a strong converter bus. And the installation of a synchronous machine is essential in an isolated weak network to re-start after a shutdown of HVDC and to increase the system strength. However, a conventional static excitation system has some problems which are harmonic instability and the system stress due to overvoltage. To reduce these problems, the new excitation system, which has 4-quadrant chopper, is proposed. As the proposed system provides the capability to allow reverse current and isolate between AC network and excitation power, problems of overvoltage and harmonic instability can be solved. The investigation is performed and confirmed by the time domain digital simulation using PSCAD/EMTDC program.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.271-273
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• 2002

Switching power supply are widely used in many industrial field. Power factor correction(PFC) has become an increasingly necessary feature in new power supply designs. The power factor correction circuit using boost converter used in input of power source is studied in this paper. In a boost power factor correction circuit there are two feedback control loops, which are a current feedback loop and a voltage feedback loop. In this paper, it is analyzed regulation performance of output voltage and compensator to improve of transient response that presented at continuous conduction mode(CCM) of boost PFC circuit. The validity of designed boost PFC circuit is confirmed by simulation and experimental results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.502-507
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• 2004

The forward planar transformer, which had power capacity of 300 W, input voltage of 220 V, output voltage of 15 V, and switching frequency of 300 KHz, was designed and manufactured by using the planar core with large effective area and the flat copper leadframes for miniaturization and high efficiency of the switching mode power supply (SMPS). As well as, a forward converter equipped with the above mentioned planar transformer was manufactured and electromagnetic characteristics were investigated. The numerical value of turns for 1st and 2nd winding were 15 and 2 respectively The self inductance of 1st winding was 1.592 mH, very low leakage inductance of 2.7 $\mu$H, and the coupling factor of 0.928 were obtained at switching frequency of 300 KHz. The high efficiency of 88.62 % for the SMPS equipped with planar transformer was obtained at power capacity of 300 W.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.378-380
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• 1999

Interleaved dual boost 컨버터는 전력분배 시스템에서 입력 전류 리플을 줄이고 스위칭 손실을 줄일 수 있고, 필터 없이 입력라인 고조파 성분을 줄일 수 있으며, 더불어 역률 개선의 효과를 이룰 수 있다. 본 논문에서는 Interleaved Dual Boost(IDB) 컨버터를 운전하는 경우에 있어서 상태 공간 평균화법을 사용하여 소 신호 해석을 수행하였다. 그 해석 결과로 얻진 제어 전달 함수를 바탕으로 IDB 컨버터에 적합한 수 개의 제어기를 설계하였다. 시뮬레이션을 행한 결과로 얻어진 여러 가지 제어기 타입의 각 특성을 분석하고 그 중 IDB 컨버터로 가장 적절한 제어기를 제안하였다.