• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.169-172
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• 2006

This paper presents the single-stage High Power Factor AC/DC Two-Switch Forward Converter (TSFC). Recently, due to growing concern about the harmonic pollution of power distribution systems and the adoption of standards such as ICE 61000-3-2 and IEEE 519, There is a need to reduce the harmonic contents of AC line currents of power supplies. This research proposed the single-stage two switch forward circuit for low voltage and high current output. The principle of operation, feature and design considerations are illustrated and verified through the simulation with a 200W(5V, 40A) 200kHz MOSFET based experimental circuit.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.644-652
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• 2016

This paper presents an improved single-stage ac-dc LED-drive flyback converter using the transformer-coupled lossless (TCL) snubber. The proposed converter is derived from the integration of a full-bridge diode rectifier and a conventional flyback converter with a simple TCL snubber. The TCL snubber circuit is composed of only two diodes, a capacitor, and a transformer-coupled auxiliary winding. The TCL snubber limits the surge voltage of the switch and regenerates the energy stored in the leakage inductance of the transformer. Also, the switch of the proposed converter is turned on at a minimum voltage using a formed resonant circuit. Thus, the proposed converter achieves high efficiency. The proposed converter utilizes only one general power factor correction (PFC) control IC as its controller and performs both PFC and output power regulation, simultaneously. Therefore, the proposed converter provides a simple structure and an economic implementation and achieves a high power factor without the need for any separate PFC circuit. In this paper, the operational principle of the proposed converter is explained in detail and the design guideline of the proposed converter is briefly shown. Experimental results for a 40-W prototype are shown to validate the performance of the proposed converter.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.103-111
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• 2024

We address the problematic issue of blinking in residential LED lighting systems-a phenomenon that has recently become a significant concern due to voltage sags caused by high-power household appliances. To combat this, we developed a two-stage LED converter with integrated anti-blinking circuitry, specifically designed for T5 LED indirect lighting fixtures. The first stage employs a Power Factor Correction (PFC) boost circuit to enhance voltage stability by aligning the voltage and current phases, thereby minimizing power losses. The second stage, a meticulously engineered DC-DC buck converter, ensures stable lighting despite electrical fluctuations. Rigorous testing has confirmed our converter's efficacy in maintaining consistent light output without blinking, thereby substantially improving user comfort and adhering to strict standards for harmonic distortion and electromagnetic compatibility. Our breakthrough provides a robust solution to a pressing issue, marking a significant advancement in LED lighting technology.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.2
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• pp.65-72
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• 2004

Switching power supply systems are widely used in many industrial fields. Power factor correction (PFC) circuits have a tendency to be applied in new power supply designs. The input active power factor correction (APFC) circuits can be implemented in either the two-stage approach or the single-stage approach. The two-stage approach can be classified into boost type PFC circuit and dc/dc converter. The power factor correction circuit with a boost converter used as an input power source is studied in this paper. In a boost power factor correction circuit there are two feedback control loops, which are a current feedback loop and a voltage feedback loop. In this paper, the regulation performance of output voltage and compensator to improve the transient response presented at the continuous conduction mode (CCM) of the boost PFC circuit is analyzed. The validity of designed boost PFC circuit is confirmed by MATLAB simulation and experimental results.

• Journal of Power Electronics
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• v.4 no.4
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• pp.246-255
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• 2004

Ac-dc PWM single-stage converters that integrate the PFC and dc-dc conversion functions in a single switching converter have been proposed to try to minimize the cost and complexity associated with implementing two separate and independent switch-mode converters. In this paper, two simple ac-dc single-stage PWM full-bridge converters are considered - one current-fed, the other voltage-fed. The operation of both converters is explained and their properties are noted. Experimental results obtained from simple lab prototypes of both converters are presented, then compared and discussed.

• Journal of Power Electronics
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• v.11 no.2
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• pp.188-193
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• 2011

A highly efficient AC-DC converter for small wind power generation systems using a brushless DC generator (BLDCG) is presented in this paper. The market standard AC-DC converter for a BLDCG consists of a three-phase diode rectifier and a boost DC-DC converter, which has an IGBT and a fast recovery diode (FRD). This kind of two-stage solution basically suffers from a large amount of conduction loss and the efficiency greatly decreases under a light load, or at a low current, because of the switching devices with a P-N junction. In order to overcome this low efficiency, especially at a low current, a three-phase bridgcless converter consisting of three upper side FRDs and three lower side Super Junction FETs is presented. In the overall operating speed region, including the cut-in speed, the efficiency of the proposed converter is improved by up to 99%. Such a remarkable result is validated and compared with conventional solutions by calculating the power loss based on I-V curves and the switching loss data of the adopted commercial switches and the current waveforms obtained through PSIM simulations.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.1
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• pp.31-37
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• 2015

This paper proposes a 3.3-kW bi-directional EV charger with V2G and V2H functions. The bi-directional EV charger consists of a DC-DC converter and a DC-AC inverter. The proposed EV charger is suitable for wide battery voltage control due to the two-stage configuration of the DC-DC converter. By employing a fixed-frequency series loaded resonant converter as the isolated DC-DC converter, zero-current-switching can be achieved regardless of battery voltage variation, load variation, and power flow. A 3.3-kW prototype of the proposed EV charger has been built and verified with experiments, and indicates a maximum efficiency of 94.39% and rated efficiency of 94.23%.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.153-155
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• 2019

This paper proposes a two-phase interleaved bridgeless single-stage ac-dc converter with magnetic integration that can achieve CCM power factor correction without input current sensing. All switches achieve ZVS turn-on and all diodes achieve ZCS turn-on for the whole grid cycle. SDAB-based modulation strategy is applied which results in simple power control and wide range output voltage. A flux cancellation method to integrate the interleaved transformer is firstly proposed in this paper to reduce the core size and loss. Experimental results on a 1.7-kW, 50kHz prototype are given to verify the principle and advantages of the proposed ac-dc converter.

• Journal of the Semiconductor & Display Technology
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• v.7 no.2
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• pp.23-27
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• 2008

Recently, regulation for THD (Total Harmonic Distortion) such as IEC 61000-3-2, IEEE 519 is being reinforced about a product which directly connects to AC line in order to prevent distortion of common power source in electronic equipment and electrical machinery. In order to satisfy these regulations, conventional circuits were used two-stage structure attached power factor correction circuit at ahead of converter but this method complicate the circuit and then a number of element increases thereupon the cost of production rises. in this paper, we propose a high efficiency single-stage 300W PFC fly-back converter that improved power factor and efficiency than conventional two-stage power module.

• 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.