• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2033-2035
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• 1998

This paper describes a DC-DC converter connected two unites inverters, a half-bridge type of high frequency resonance inverter, at the input with parallel. The proposed paper certified that theorem waveforms are equal to experiment waveforms, in addition, it estimated characteristics such as characteristic of average power, characteristic of average output voltage, characterisic of output voltage ripple etc., for designing the device with normalized parameter value.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1318-1320
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• 2000

In this paper, DC/DC converter has been composed of a capacitor which has not only a source division function but a resonant function instead of a previous source division capacitor. In addition to the proposed circuit is introduced a soft switching technique (ZVS). The proposed paper certified that theoretical waveforms are equal to experiment waveforms of power, output voltage, voltage ripple etc. and to be possible to control using division ratio.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.2
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• pp.31-37
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• 2001

This paper propose ZVS-HB type resonant DC/DC converter have earth different output characteristics using division ratio, not only a source division function but a resonant function and soft switching technique(ZVS, ZCS) instead of conventional source division capacitor. Circuit analysis generally described using normalized parameters most of characteristics with division ratio of source division capacitor. Also, this paper citified a rightfulness of characteristic analysis in comparison with a theoretical values and a experimental values obtain from experiment using Power-MOSFET.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.104-107
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• 2007

Among the alternative energy sources, the solar energy is recognized as an important energy source and its application is increasing. Especially in future, the hybrid solar energy generation system with battery will be widely used as an independent distributed power generation system. In this paper, a solar power hybrid home generation system using a contact-less power supply (CPS) that can transfer an electric power without any mechanical contact by using magnetic coupling instead of the power transfer by directly supplying the DC power to the home electric system is proposed. The proposed system consists of a ZVS boost converter, a half bridge LLC resonant converter and contact-less transformer.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1401-1403
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• 2005

This paper presents generalized small-signal models for asymmetrically-driven double-ended dc-to-dc converters. The proposed small-signal models include the effects of the parasitic resistances, which have dominant influence on the damping of the secondary power stage double-pole. To confirm the validity of new models, an asymmetrical half-bridge converter with center-taped rectifier and a forward-flyback converter with current doubler rectifier were built, and their performances were compared with the theoretical predictions.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.317-322
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• 2003

A novel three-level DC/DC converter (TLC)for high power applications operating from high input voltage Is proposed. Its switch voltage stress can be ensured to be only one-half of the Input voltage. Nevertheless, since all input voltage is applied to the transformer primary side, it has good turns ratio. The driving method of each module is same as those of the conventional phase-shifted ZVS full bridge PWM converter (PSFB) and the zero-voltage-switching (ZVS) of the leading leg are achieved exactly in the same manner as that of the PSFB. Moreover, its three-level operation can considerably reduce the current ripple through the output inductor and it has no problems of the DC-link voltage unbalance. Therefore, it features a low voltage stress, high efficiency, low EMI, high power density, and small sized filter. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 200W, 600V/DC-48V/DC prototype are presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.1
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• pp.20-26
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• 2002

HID(high intensity discharge)lamps include high pressure mercury lamp, high pressure sodium lamp and metal halide lamp. Metal halide lamps have been considered to be one of the most erective light sources. These lamps have good efficiency, good color rendering and good focusing capability. The objective of this research is to alum on the metal halide lamp(MH70W) by the developed electronic ballast with free voltage input(AC 100∼277V). The developed electronic ballast consists of a free voltage input converter, a flyback converter ＆ half-bridge inverter, ignitor ＆ protector and control1er. Experimental results show that developed electronic ballast turns on the metal halide lamp(MH70W) with free voltage input(AC 100∼277V) very well.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.3
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• pp.248-256
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• 2005

This paper presents the design method of the DC/DC converter using flat transformer which is suitable for midium or large capacity and high density power supply. Flat transformer module is composed and manufactured of multi-transformers in parallel and has a number of parallel single turn secondary windings. Therefore, its leakage inductance is highly decreased and it is more suitable for high frequency operation than conventional one. In this paper, we manufactured and tested 750W AC/DC converter with variable output powers to verify the performance of the flat transformer.

• Proceedings of the KIPE Conference
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• 2004.11a
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• pp.71-75
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• 2004

In this paper, in order to develop a simple and high efficient ballast without an external igniter, a half-bridge type ballast with a coupled inductor and a frequency controlled synchronous rectifier is proposed. The internal LC resonance of the buck converter is used In generate a high voltage pulse for the ignition, and the coupled inductor filter is used for steady state ripple cancellation. Also, a synchronous buck converter is applied for the DC/DC converter stage. In order to improve the efficiency of the ballast, a frequency control method is proposed. This scheme reduces a circulation current and turn off loss of the MOSFET switch on the constant power operation, which results in increase of the efficiency of the ballast system about $4\%$, compared to a fixed frequency control. It consists a 2-stage version ballast with a PFC circuit. The results are verified with hardware experiments.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.1-9
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• 2003

In this paper, prototype of high-power-factor single-stage electronic ballast for fluorescent lamp is designed and implemented. A new low cost single stage high power factor electronic ballast for fluorescent lamps is based on integration of two-boost converter and LC type high frequency resonant inverter. The proposed ballast is combined by simple construction, because full bridge rectifier diode is eliminated and simple control circuit is applied. Boost converter operate in the voltage of positive and negative half cycle respectively at line frequency (60㎐), operation in discontinuous conduction mode performs high power factor. The experimental results show the good performance as PF 0.99, THD 15.4%, and CF 1.65 at output 63.5〔W〕.