• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.125-126
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• 2008

전력계통에서 고장, 선로가압 등으로 인하여 개폐서지가 발생할 수 있다. 따라서, 본 논문에서는 한전의 실 배전계통에서 고장으로 인한 개폐서지를 분석하였다. EMTP를 이용하여 계통을 모델링하고, 고장위치를 다양하게 변경시키면서 개폐서지에 대한 분석을 수행하였다. 개폐서지 발생 시 상하단의 상호간의 영향에 대하여 분석하였다. 분석결과 상호간의 영향은 미비함을 확인하였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1952-1953
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• 2007

회로 구성 방법에 따라 등가 회로의 파형이 다르게 나타나는 경우가 있는데 본 논문에서 분석한 500kV 시스템에서 J.R. Marti가 제안한 주파수 의존 모델과 II-등가회로를 각각 이용했을 경우를 예로 들 수 있다. 본 논문에서는 각각의 파형을 비교 분석하고 500kV 시스템에서 스위치 개폐에 따른 전압, 전류 파형을 분석하므로서 JMarti line의 특성을 제시하였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1940-1941
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• 2007

양질의 전력을 요구하는 경향으로 인해 과도현상이 높은 관심의 대상이 되고 있다. 스위치를 개방 후 반 사이클 후에는 스위치 양극간 전압은 발전기 전압 첨두치의 2배가 된다. 본 논문에서는 EMTP에서 제공하는 선로모델 중 비연가 선로와 연가선로를 이용하여 개폐서지와 선로모델과의 관계를 모델링 하였다. 송전단 측에서는 스위치 개폐 후 두 선로모델 사이의 전압 파형에는 큰 차이가 없었으나 수전단 측에서는 두 선로모델 간에 현저한 차이를 보여주었다.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1187-1189
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• 2002

In the case of an existing high frequency inverter is became forced extinction by quick load change, due to be connected with series inductor on switch, it is destroyed or is generated conduction loss by resistance component in reactor. And, In the operation of high current with a soft switching, conduction loss can not neglect. In this paper, for the high current power source, we make sure of soft swtching operation and reducing surge when the forced extinction by using a connected switch with series inductor. Also, we poropos a topology of the half bridge type high frequency inverter that can be realized high amplitude operation of the load current. And, analyze the circuit to decide an opmtial circuit parameter.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.319-322
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• 1999

This paper presents a novel single-stage Power Factor Corrected(PFC) AC/DC forward converter with semi-automatic current shaping in order to achieve the unity power factor and an isolated output. Since the proposed circuit is combined a boost converter used for PFCs with a forward converter used for DC to DC conversion, the over-all size of system could be reduced. And thanks to the zero voltage switching(ZVS) in both switches, the voltage stress can be reduced considerably. A simple auxiliary circuit adopted into the secondary of transformer is composed of lossless components for reducing surge voltage. A prototype which has tow IGBT(Insulated Gate Bypolar Transistor) modules as switching device is manufactured to evaluate the proposed topology. The characteristics of the proposed circuit are tested, and the validity is verified by experimental results.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1704-1706
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• 2002

With increasement of use in electricity energy, quality of electric apparatus has been recognized as important factor in distribution and transmission line. Especially In laboratories, lightning and switching impulse performances of electric apparatus have been carrying out by impulse voltage generator (IVG), simulated into lightning and switching surge circuit. In this paper, we describe triggering system of impulse voltage generator(IVG) for extra high voltage, which has been newly designed.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.292-294
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• 2005

A new zero voltage switching (ZVS) 2-transformer boost converter is proposed in this paper. The proposed converter has the advantage that the magnetizing inductor of the transformer acts for the boost inductor without additional inductor. Moreover, ZVS of main switches and auxiliary switches can be achieved, and the switch turn-off surge problem of conventional isolated boost converter is effectively solved. The operational principle, DC voltage gain, and ZVS characteristics are analyzed. To confirm the validity of the proposed converter, simulation results with 200w, 24Vdc/200Vdc specification are presented.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.459-463
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• 2001

Since recent inverters are formed IGBT VVVF inverter its switching speed has been increased relative to the conventional inverters and the motor design based on the switching surge voltage at the inverter output is very important factor. Therefore, motor and inverter should be designed to have the optimal characteristics by considering the mutually limited conditions. On this research the design technology characteristics for inverter driving traction moor is compared to the products in Korea and the analysis is performed. Thus, it is intend to re-estimate the technology level and introduce the products by HHI, which is driving on Seoul subway line 6 since December, 2000.

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.56-61
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• 2018

In this paper, a new type of active snubber was proposed to lower the excessive rated voltage of the clamp capacitor which was a problem in the conventional circuit by applying auxiliary winding into the active snubber. A simplified equivalent circuit of the proposed snubber was derived by applying it to QR flyback converter, and the equivalent circuits for each switch state was shown under the steady-state condition. In addition, the maximum voltage of the clamp capacitor as well as the main switch was found by using the steady-state equations. In particular, it was found that the clamp capacitor voltage could be controlled by the auxiliary winding ratio. In order to verify the utility and practicality of the proposed converter with auxiliary winding type active snubber circuit, a prototype with an output voltage of 19V and a maximum load current of 6A was produced and the results were reported.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.4
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• pp.322-329
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• 2012

This paper proposes a non-isolated bidirectional soft-switching converter with high voltage for high step-up/down and high power applications. Compared to the conventional boost converter the proposed converter can achieve approximately doubled voltage gain using the same duty cycle. The voltage ratings of the switch and diode are reduced to half, which result in the use of devices with lower $R_{DS(ON)}$ and on drop leading to reduced conduction losses. Also, voltage ratings of the passive components are reduced, and therefore the total energy volume is reduced to half. Further, the switch is turned on with ZVS in the CCM operation which results in negligible surge caused leading to reduced switching losses. The validity of the proposed converter is proved through a 10kW prototype.