• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.4
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• pp.361-370
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• 2006

A single-stage single-switch flyback converter with synchronous rectifier is proposed. The proposed single-stage single-switch technique meets the IEC 61000-3-2 harmonic requirements. The proposed SR is the voltage driven synchronous rectifier (VDSR) which operates depending on the voltage drop across the drain and source of the MOSFET. Experimental results for the 85W (12V /7.1A) proposed converter are shown.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.986-989
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• 2002

This paper proposes a new single stage power factor correction (PFC) full bridge converter which operates at continuous conduction mode(CCM). The proposed single stage PFC consists of typical zero voltage switching(ZVS) full bridge DC/DC converter, two transformer auxiliary windings, and two small inductors, and two diodes. Neither additional active switch nor any control circuit are added for PFC resulting in very low cost. The proposed converter provides input power factor correction with CCM control and tight output voltage regulation. All switching devices are operated under ZVS with minimum voltage stress. Operation principle and analysis are explained and verified with computer simulation and experimental results on a 1.2kW, 100kHz prototype.

• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2288-2296
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• 2015

This paper proposes a novel systematic modeling approach for an integrated single-stage power converter in order to predict its dynamic characteristics. The basic strategy of the proposed modeling is substituting the internal converters with an equivalent current source, and then deriving the dynamic equations under a standalone operation using the state-space averaging technique. The proposed approach provides an intuitive modeling solution and simplified mathematical process with accurate dynamic prediction. The simulation and experimental results by using an integrated boost-flyback converter prototype provide verification consistent with theoretical expectations.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.238-241
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• 1999

Analog-to-digital converter has attracted a lot of interests as one of the most prospective area of an application of Josephson Junction technology. Recently, the development of a digital-to-analog converter has been pursued to achieved the high performance. One of the main advantage in using single flux quantum logic in a digital-to-analog converter is the low voltage drop in a single Josephson Junction and hence the resolution of the output voltage of this digital-to-analog converter can be very high. In this work, we have used a software, called WRspice, to study a voltage multiplier circuit which is the basic block in building a digital-to-analog circuit. In simulation, we operated a voltage multiplier with .4 Josephson Junctions per stage and studied the dependence on the circuit bias currents and the circuit inductors of the voltage multiplier. Our simulation results showed a fast operation and reasonable circuit margins.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.351-354
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• 1996

A zero-voltage-transition(ZVT) full bridge (FB) boost converter for single stage power factor correction (PFC) in distributed power system is proposed. A simple auxiliary circuit provides zero-voltage-switching(ZVS) condition to all semiconductor devices without imposing additional voltage and current stresses and loss of PWM capability. The proposed boost converter provides both input power factor correction and direct conversion from $110{\sim}220VAC$ line to 300VDC bus with single power stage. Operational principle, analysis of the proposed converter are described and verified by computer simulation and experimental results from a 1.5 kW, 80 kHz laboratory prototype.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.2
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• pp.84-94
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• 2013

In case when the existing TRIAC phase controlled dimmer is drove for the LED lighting equipments, there are many problems such as the LED flicker in low phase-angles, the acoustic noise and elements damage by increase of the peak voltage in the input filter capacitor, mulfunction by insufficiency of the TRIAC holding current, and the abnormal oscillation by LC resonant. In this paper, we proposes the single-stage quasi-resonant PSR(Primary Side Regulation) PWM converter, and the design, the simulation and experiment are performed. As a result, it could confirm that the proposed PWM converter is the lighting equipments for LED drive which can alternate the existing 60W class incandescent bulbs and it has the high drive performance of the efficiency 80% and over, the power factor 0.95 and over under the normal voltage 220V. Finally, total harmonic distortion(THD) is gratified with a standard[1] of the lighting equipments and the durability is evaluated as the high reliablilty of 150,000 hours and over.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.88-90
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• 2012

A study on an integrated single stage AC/DC converter is presented in this paper. The input current can be controlled by the auxiliary winding($L_{aux}$), auxiliary primary winding($N_3$), and the boost inductor($L_B$) which are designed to operate in discontinuous conduction mode(DCM) to reduced the total harmonic distortion(THD) of input current. The auxiliary primary winding($N_3$) is critically selected in order to compress the input capacitor voltage($V_{in}$) as well as to reduce the current stress of the switch(Q). Low total harmonic distortion(THD), low input voltage($V_{in}$) in universal input voltage($V_{AC}$), low current stress at the switching device and high efficiency are the main consideration keys in this design to achieve high performance system with low cost of single stage AC/DC converter. A 30W single stage AC/DC prototype converter is under study.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.538-541
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• 2001

This paper analyzed PFC of active clamp ZVS flyback converter by adding two method PFC (Power Factor Correction) circuit - Two-Stage and Single-Stage. It improves on Flyback converter's disadvantage - loss increasing by switching, noise increasing, high voltage stress of switch - by adding active clamp circuit. Simulation results show to improve the input PF of 300W ZVS flyback converter by adding Single-Stage, Two-Stage PFC circuit.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.187-189
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• 2003

Conventional Switched Mode Power Supplies(SMPS) with diode-capacitor rectifier have distorted input current waveform with high harmonic content. Typically, these SMPS have a power factor lower than 0,65. To improve with this problem the power factor correction(PFC) circuit of power supplies has to be introduced. Specially. to the reduce size and manufacture cost of power conversion device, the single-stage PFC converter is increased to demand as necessary of study. in this paper, The comparative analysis of power factor correction circuit using Feedforward control with average current mode flyback converter(single-stage) and boost converter(two-stage). Also, the validity of designed and manufactured high power factor flyback converter and boost converter is confirmed by simulation and experimental results.

• Journal of Power Electronics
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• v.13 no.4
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• pp.592-599
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• 2013

This paper investigates a new isolated single-phase AC-DC converter, which integrates a modified AC-DC buck-boost converter with a DC-DC forward converter. The front semi-stage is operated in discontinuous conduction mode (DCM) to achieve an almost unity power factor and a low total harmonic distortion of the input current. The rear semi-stage is used for step-down voltage conversion and electrical isolation. The front semi-stage uses a coupled inductor with the same winding-turn in the primary and secondary sides, which is charged in series during the switch-on period and is discharged in parallel during the switch-off period. The discharging time can be shortened. In other words, the duty ratio can be extended. This semi-stage can be operated in a larger duty-ratio range than the conventional AC-DC buck-boost converter for DCM operation. Therefore, the proposed converter is suitable for universal input voltage (90~264 $V_{rms}$) and a wide output-power range. Moreover, the voltage stress on the DC-link capacitor is low. Finally, a prototype circuit is implemented to verify the performance of the proposed converter.