• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.3
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• pp.211-219
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• 2014

This paper proposes a low voltage high current LLC resonant converter for Green PC. Green PC is composed of a lot of blade PCs, and it is a centralized system to manage them in computer center. Green PC should require that its power supplies have several characteristics such as low output voltage, high output current, and high power conversion efficiency. Conventional PSFB (Phase Shift Full Bridge) converter is usually used as DC/DC converter for computer power supply because it has high power conversion efficiency thanks to ZVS (Zero Voltage Switching) operation under middle and high load conditions. However, this converter has some problems such as large switching noise and limitation of ZVS operation under light load condition. In order to improve the performance of power supply for Green PC, a new power supply using popular high efficiency LLC resonant converter for low voltage and high current application is proposed in this paper. The proposed power supply has ZVS capability over the entire load range, thus resulting in good efficiency and high switching frequency. Experimental results verify the performance of the proposed power supply for Green PC using 2[kW] (19[V], 105[A]) rated prototype converter.

• Journal of IKEEE
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• v.23 no.3
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• pp.962-970
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• 2019

In this paper, the non-isolation, high-efficiency and high-voltage-output DC-DC converter using the self-driven synchronous switch is proposed. The proposed converter achieves high-voltage-output by applying a tapped inductor to the conventional boost DC-DC converter structure, and it reduces the voltage stress of main switch applying the lossless capacitor-diode (LCD) snubber to the switch. And the proposed converter applies the synchronous switch instead of the diode to the output part, and thus it resolves the reverse recovery problem and achieves high-efficiency. The synchronous switch of proposed converter uses the self-driven method and has a simple structure. In this paper, the operation principle of proposed converter is explained, and then, a design example of the converter prototype is presented. And the characteristics of the proposed converter are shown through experimental results of the prototype made with the designed circuit parameters.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.314-317
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• 1997

The purpose of this study is developing a converter which is able to convert a 300[KW] power, and is a DC power supply output a 1500[V] DC voltage for inverter driving. The power converter is driven by two converter serisely and keep a high power factor of power source. This system is haven all the characteristic of voltage source converter by having a processing ability of regenerating power. The two converters controls a PWM modulation and output voltage using a only one 16 bit DSP processor.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.145-149
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• 2000

A single-stage power factor correction AC/DC converter with a simple link voltage suppressing circuit (LVSC) for the universal line application is proposed. Using this simple circuit a low link voltage can be realized without deadbands at line zero-crossings. The proposed converter is analyzed and a prototype converter with 5C, 12V output is implemented to verify the performance. The experimental results show that the link voltage stress and efficiency are about 447V and 81%, respectively.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.160-164
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• 2000

Digital to analog converters based on the Josephson effect are promising for voltage standard, because they produce voltage steps with high precision and good stability. In this paper, we made a simulation study on RSFQ D/A converter. RSFQ D/A converter was composed of NDRO cells, T(toggle) flip-flops, D flip-flops, Splitters and Confluence Buffers. Confluence Buffer was used to reset the D/A converter. We also obtained operating margins of the important circuit values by simulational experiments.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.144-146
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• 1998

In this study Dead time equivalent resistance of Voltage source power converter is very important in current controller design. And Non-linear Modeling method can be applied in Power converter analysis. Using Describing Function method and Non-linear Resistance Modeling. Voltage Source Power Converter Bode diagram and Current controller analysis method are more reality.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.4
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• pp.315-322
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• 2009

In the conventional boost converter, the actual duty cycle is limited as the output voltage increases due to increased voltage and current stress of the switch and diode and voltage surge caused by diode reverse recovery. In this paper a new non-isolated boost converter suitable for high gain applications is proposed. The proposed converter has voltage gain of around 6 when the duty cycle is 0.5. Since ZVS is achieved under CCM, the proposed converter has wide ZVS range. Also, voltage ratings of switch and diode are the same as one third of output voltage, and ratings of input and output passive components are reduced due to the interleaving. In addition voltage surge caused by diode reverse recovery is negligible due to ZCS turn-off of diodes. Operating principle of the proposed converter is described and validated through theoretical analysis, simulation and experiment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.4
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• pp.891-896
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• 2011

This paper describes the differential voltage-to-frequency converter which is realized current conveyor circuits. The output frequency of the differential voltage-to-frequency converter is proportional to the difference of two input voltages. The designed circuit is simulated by HSPICE. The range of input voltage difference is from several volts to several milli-volts. From the simulation results the error is less than from -1.9% to +1.8% compared to the calculated values.

• Journal of Power Electronics
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• v.7 no.4
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• pp.328-335
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• 2007

A conventional Single-Stage Power-Factor-Correction (PFC) AC/DC converter has a link capacitor voltage problem under high line input and low load conditions. In this paper, this problem is analyzed by using the voltage conversion ratio of the DC/DC conversion cell. By applying this analysis, a new Single-Stage PFC AC/DC converter with a boost PFC cell integrated with a Voltage-Doubler Rectified Asymmetrical Half-Bridge (VDRAHB) is proposed. The proposed converter features good power factor correction, low current harmonic distortions, tight output regulations and low voltage of the link capacitor. An 85W prototype was implemented to show that it meets harmonic requirements and standards satisfactorily with near unity power factor and high efficiency over universal input.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.11
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• pp.1737-1742
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• 2012

The scott transformer is used to supply single-phase power to the AC railway system. Since the scott transformer is a passive facility, it cannot regulate load-side voltage according to load change. Meanwhile, the Voltage Source Converter (VSC) is able to convert the voltage and control active and reactive power. In this paper, the feasibility of a AC railway system based on Back-to-Back (BTB) VSC which is composed of a rectifier, a DC-DC converter, a inverter, has been proposed. A three-phase to single-phase BTB VSC is modeled. The proposed AC railway system based on BTB VSC is tested on Matlab/Simulink.