• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.56-61
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• 1998

A soft-switching three-level chopper-inverter system was built for high-power applications like Power Conditioning System (PCS) for Superconductive Magnetic Energy Storage (SMES). The system can handle 1800-VDC, 200-A peak, and 250-kW output power. The system was designed to operate with 20-KHz PWM operation with the aid of state-of-the-art zero-current transition type soft-switching. The system is based on the Power Electronics Building Block (PEBB) concept.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1669-1677
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• 2016

A new auxiliary circuit for boost, buck, buck-boost, Cuk, SEPIC, and zeta converters is introduced to provide soft switching for pulse-width modulation converters. In the aforementioned family of DC-DC converters, the main and auxiliary switches turn on under zero current transition (ZCT) and turn off with zero voltage and current transition (ZVZCT). All diodes commutate under soft switching conditions. On the basis of the proposed converter family, the boost topology is analyzed, and its operating modes are presented. The validity of the theoretical analysis is justified by the experimental results of a 100W, 100 kHz prototype. The conducted electromagnetic emissions of the proposed boost converter are measured and found to be lower than those of another ZCT boost converter.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.371-376
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• 2005

In this paper, a new a new full-bridge soft-switching phase shift PWM DC-DC Converter has been proposed, which is suitable for fuel cell based power generation system. The proposed converter has outstanding advantage over the conventional DC-DC converter with respect to high efficiency, high power density, and hish component utilization. In special. the proposed converter has predominant high boosting output voltage and high efficiency characteristics under the inherently severs low output voltage of the fuel cell through the overall load conditions. Moreover, the developed converter has been experimentally tested with the help of a fuel cell simulator, and can generate the V-I characteristics of proton exchange membrane(PEM) fuel cell, so that the performance of the proposed converter could be effectively examined and the validity of the converter could be verified.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.1047-1050
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• 1998

This paper describes an advanced prototype of voltage-fed zero voltage soft-switching PWM resonant inverter with an active voltage clamped capacitor, which is put into practice for high-frequency high-power induction-heated appliances. This application-specific quasi-resonant inverter using the latest generation IGBTs for soft-switching can regulate its output power under a principle of a fixed frequency ZVS-PWM strategy. Its operating principle and unique features are presented as compared with a conventional quasi-resonant ZVS inverter for induction-heated cooker, together with its power regulation characteristics on the basis of its simulation and experimental results. The steady-state performances of this inverter developed for multi-burner type induction-heated food cooking appliance are evaluated and discussed from a practical point of view.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.3
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• pp.146-152
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• 2015

In this paper, we propose a boost DC-DC converter using a modification of the passive auxiliary resonant snubber circuit with a DC-DC converter in a typical active auxiliary resonant snubber-bridge inverter. The proposed boost DC-DC converter is small compared to the DC-DC converter according to the soft-switching scheme that requires a general auxiliary switch by realizing the soft switching operation as a DC-DC converter which does not require an auxiliary switch. It is light-weight, switch the turn-on and turn-off switching loss at the time of the superposition of the voltage and current is extremely small, so small. And the reduction of the surge voltage and current of the switch. In addition, the proposed boost DC-DC converter has a high efficiency over a wide load characteristics change area than conventional hard switching PWM boost converter using an RC snubber loss.

• Journal of Power Electronics
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• v.15 no.3
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• pp.652-659
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• 2015

This paper presents a new hybrid soft switching dc-dc converter with a low circulating current and high circuit efficiency. The proposed hybrid converter includes two sub-converters sharing two power switches. One is a three-level PWM converter and the other is a LLC converter. The LLC converter and the three-level converter share the lagging-leg switches and extend the zero-voltage switching (ZVS) range of the lagging-leg switches from nearly zero to full load since the LLC converter can be operated at f_sw (switching frequency) $\approx$ f_r (series resonant frequency). A passive snubber is used on the secondary side of the three-level converter to decrease the circulating current on the primary side, especially at high input voltage and full load conditions. Thus, the conduction losses due to the circulating current are reduced. The output sides of the two converters are connected in series. Energy can be transferred from the input voltage to the output load within the whole switching period. Finally, the effectiveness of the proposed converter is verified by experiments with a 1.44kW prototype circuit.

• Journal of Power Electronics
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• v.15 no.2
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• pp.299-308
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• 2015

This study proposes four novel pulse width modulation (PWM) shoot-through control methods for impedance source (IS) galvanically isolated DC-DC converters. These methods are derived from a PWM control method with shifted shoot-through introduced by the authors in 2012. In contrast to the baseline solution, where the shoot-through states are generated by the simultaneous conduction of all transistors in the inverter bridge, our new approach is based on the shoot-through generation by one inverter leg. The idea is to increase the number of soft-switched transients and, therefore, decrease the dynamic losses of the front-end inverter. All the proposed approaches are experimentally verified through an insulated-gate bipolar transistor-based IS DC-DC converter. Conclusions are drawn in accordance with the results of the switching loss analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.458-465
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• 2013

This paper proposes a novel soft-switched auxiliary resonant circuit to provide a Zero-Voltage-Transition at turn-on for a conventional PWM boost converter in a PFC application. The proposed auxiliary circuit enables a main switch of the boost converter to turn on under a zero voltage switching condition and simultaneously achieves both soft-switched turn-on and turn-off. Moreover, for the purpose of an intelligent multi-chip power module fabrication, the proposed circuit is designed to satisfy several design constraints including space saving, low cost, and easy fabrication. As a result, the circuit is easily realized by a low rated MOSFET and a small inductor. Detail operation and the circuit waveform are theoretically explained and then simulation and experimental results are provided based on a 1.8 kW prototype PFC converter in order to verify the effectiveness of the proposed circuit.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.643-645
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• 1999

The conventional high frequency phase-shifted full bridge dc/dc converter has a disadvantage that a circulating current flows through transformer and switching devices during the freewheeling interval. Due to this circulating current, RMS current stress, conduction losses of transformer and switching devices are increased. To alleviate this problem, this paper provides a circulating current free type high frequency soft switching phase-shifted full bridge (FB) dc/dc converter with the modified energy recovery snubber (ERS) attached at the secondary side of transforemr.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.385-387
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• 1996

A novel two stage soft-switching ac-to-dc convener with power factor correction is proposed. The proposed convener provides zero-voltage-switching (ZVS) condition to main switch of boost pre-regulator without auxiliary switch. Comparing to the conventional two stage approach(ZVS-PWM boost rectifier followed by off-line ZVS dc-dc step down converter), the proposed approach is simple and reducing EMI noise problem. A new simple DC-linked energy feedback circuit provides zero-voltage-switching condition to boost pre-regulator without imposing additional voltage and current stresses and loss of PWM capability. Operational principle, analysis, control of the proposed converter together with the simulation results of 1KW prototype are presented.