• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.626-628
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• 2004

This paper describes an 8-bit CMOS folding A/D converter for set-top box. Modular low-power, high-speed CMOS A/D converter for embedded systems aims at design techniques for low-power, high-speed A/D converter processed by the standard CMOS technology. The time-interleaved A/D converter or flash A/D converter are not suitable for the low-power applications. The two-step or multi-step flash A/D converters need a high-speed SHA, which represents a tough task in high-speed analog circuit design. On the other hand, the folding A/D converter is suitable for the low-power, high-speed applications(Embedded system). The simulation results illustrate a conversion rate of 40MSamples/s and a Power dissipation of 80mW(only analog block) at 2.5V supply voltage.

• Journal of electromagnetic engineering and science
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• v.11 no.3
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• pp.161-165
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• 2011

In this paper, a high-efficiency DC-AC converter is used for wireless energy transmission. The DC-AC convertter is implemented by combining the oscillator and power amplifier. Given that the conversion efficiency of a DC-AC converter is strongly affected by the efficiency of the power amplifier, a high-efficiency power amplifier is implemented using a class-E amplifier structure. Also, because of the low output power of the oscillator connected to the input stage of the power amplifier, a high-gain two-stage power amplifier using a drive amplifier is used to realize a high-output power DC-AC converter. The high-efficiency DC-AC converter is realized by connecting the oscillator to the input stage of the high-gain high-efficiency two-stage class-E power amplifier. The output power and the conversion efficiency of the DC-AC converter are 40.83 dBm and 87.32 %, respectively, at an operation frequency of 13.56 MHz.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.120-124
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• 2001

A new technique for improving the efficiency of single-phase high-frequency boost converter is proposed. This converter includes an additional low-frequency boost converter which is connected to the main high-frequency switching device in parallel. The additional converter is controlled at lower frequency. Most of the current flows in the low-frequency switch and so, high-frequency switching loss is greatly reduced accordingly Both switching device are controlled by a simple method; each controller consists of a one-shot multivibrator, a comparator and an AND gate. The converter works cooperatively in high efficiency and acts as if it were a conventional high-frequency boost converter with one switching device. The proposed method is verified by simulation. This paper describes the converter configuration and design, and discusses the steady-state performance concerning the switching loss reduction and efficiency improvement.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.6
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• pp.77-84
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• 1997

buck type converter doesn't appear when an input voltag eis lower than an output voltage. This is the main reason the buck converter has not been used for high power factor converters. In this paper, soft switching high power factor buck converter is proposed. This converter is composed of diode rectifier, input capacitor can be small enough to filter input current, buck converter with loss less snubber circuit. Converter is operated in discontinous conduction mode, turn on of the switching device is a zero current switching (ZCS) and high powr factor input is obtianed. In addition, zero voltage switching (ZVS) at trun off is achieved and switching loss is reduced using loss less snubber circuit. The capacitor used in the snubber circuit raised output voltage. Therefore, proposed converter has higher output voltage and higher efficiency than conventional buck type converter at same duty factor in discontinous conduction mode operation. High power factro, efficiency, soft switching operation of proposed converter is veified by simulation using Pspice and experimental results.

• Journal of the Semiconductor & Display Technology
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• v.7 no.2
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• pp.7-12
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• 2008

This paper proposed DC-DC converter for fuel cell that have high voltage and high current output characteristics. It is required step-up converter to use by general power supply, because the general rated voltage of fuel cell is low about 20$\sim$50V. The miniaturization of converter and DC link voltage can be controlled and high quality of output voltage uses mainly DC-DC converter. The boost converter and buck-boost converter do not get high boosting ratio. It is that proposed boost-flyback converter. Through simulation and an experiment, it could get high boosting ratio and efficiency more than 90%.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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• pp.342-348
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• 2013

In this paper, an improved non-isolated 3-level high step-up boost converter is proposed. By using the well known duality principle, the proposed converter is derived from two-phase buck converter. Compared with the traditional boost converter and 3-level boost converter, the proposed converter can obtain very high voltage conversion ratio and the voltage stress of switching devices and diodes is only 1/4 of the output voltage. A 1 kW prototype converter is built and tested to verify performances of the proposed converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.5
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• pp.464-470
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• 2015

In this paper, a non-isolated three-level high step-up boost converter with output voltage balancing is proposed. By adding one extra inductor to the conventional three-level boost converter, the proposed converter is derived. Compared with the traditional boost converter and the three-level boost converter, the proposed converter can obtain very high voltage conversion ratio, and the voltage and current stress of switching devices and diodes are reduced. A 2.7 kW prototype converter is built and tested to verify performances of the proposed converter.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.216-222
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• 2003

Today we have excellent motor drive system using high frequency carrier PWM control voltage source inverter in the other hand, we have met serious problems caused by high frequency switching. PWM Cyclo-converter called Matrix converter is expected as the new strategy Possible to improve these problems and add some more convenient features suitable for new drive system. in this Paper, we will introduce the background, features and outline of this converter, and additionally introduce some remarkable activity on this converter

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.1
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• pp.66-69
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• 2019

This study proposes a high-efficiency phase-shifted full-bridge (PSFB) converter with a wide input voltage range. The conventional PSFB converter is a useful topology in high-power applications. This converter not only achieves the zero-voltage switching of the primary switches, but also has small RMS current in the primary side. However, because the conventional PSFB converter has large freewheeling current in the primary side when it is designed considering the hold-up time of the converter, such a converter has high conduction loss at the primary switches. To solve this problem, a new PSFB converter is proposed in this study. The experiment is implemented with an input voltage ranging from a 320 V-400 V and an output power specification of 715 W.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.492-500
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• 2013

A balanced forward-flyback converter for high efficiency and high power factor using a foward and flyback converter topologies is proposed in this paper. The conventional AC/DC flyback converter can achieve a good power factor but it has the high offset current through the transformer magnetizing inductor, which results in a large core loss and low power conversion efficiency. And, the conventional forward converter can achieve the good power conversion efficiency with the aid of the low core loss but the input current dead zone near zero cross AC input voltage deteriorates the power factor. On the other hand, since the proposed converter can operate as the forward and flyback converters during switch turn-on and turn-off periods, respectively, it cannot only perform the power transfer during an entire switching period but also achieve the high power factor due to the flyback operation. Moreover, since the current balanced capacitor can minimize the offset current through the transformer magnetizing inductor regardless of the AC input voltage, the core loss and volume of the transformer can be minimized. Therefore, the proposed converter features a high efficiency and high power factor. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a prototype of 24W LED driver are presented.