• Journal of the Korean Society of Industry Convergence
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• v.21 no.6
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• pp.361-368
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• 2018

This paper proposes a grid - connected CTTS system that can be soft switched to meet the government's effective resource allocation policy for emergency generator. In order to eliminate the system instability caused by the large inrush current generation in the system switching, a new virtual rotation coordinate method for the dissimilar power source is proposed. The proposed virtual rotation coordinate method improves the voltage detection accuracy of the voltage difference of the dissimilar power supply, and it is proved that the synchronous switching characteristic is excellent. In addition, zero current and system stabilization can be achieved by realizing zero current when blocking CTTS with instantaneous reactive power control. Simulation was carried out to verify the validity of the proposed method, and the 500[kVA] system was fabricated and verified to demonstrate the superiority of the proposed method.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.1
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• pp.59-64
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• 2008

Recently, DC-DC choppers must be increased switching frequency in order to achieve a small size, a light weight and a low noise. However, the switches of chopper are subjected to high switching power losses and switching stresses. As a result of these, the chopper system bring on a low power efficiency. To improved these, this paper is studied on a new DC-DC chopper of high efficiency operated with soft switching(that is, zero current switching and zero voltage switching, ZVCS), of semiconductor switches using in chopper. The soft switching operation is applied to a partial resonant method that the switches operate at zero current of inductor and zero voltage of capacitor in resonant circuit. And the partial resonant circuit makes use of a inductor using step-up and a snubber capacitor, the circuit topology of chopper is simple. Some simulative results on computer and experimental results confirm the validity of analytical results of the DC-DC chopper.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2553-2560
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• 2018

In Korea, there are no instances where a hydrogen fuel cell power generation system has been used in a railway vehicle. Only the basic topology has been studied. In the previous study, conventional converters using a single switch were applied to the fuel cell power generation system. Therefore, current stress on the switch at converter on-off transitions would be large when controlling a large-capacity railway vehicle. In addition, since the input side ripple is also large, there is a problem with a shortening of the lifetime of both the fuel cell power generation system and the inductor. In this paper, a soft-switching transformer inductor boost converter for fuel cell powered railway vehicles was proposed. A technique to reduce both the switching current stress generated during on-off transitions, and the input ripple current flowing in the inductor were studied. The soft-switching TIB converter uses a transformer-type inductor to configure the entire circuit in an interleaved method, and reduces both input current ripple and the current ripple of the inductor and switch.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.45-48
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• 2003

Recently the PDP is the most remarkable media for a next generation display device. In this paper, we proposed the PDP dedicated DC-DC converter using a new soft switching method because the PDP has a lot of power dissipation so we need to develope. The proposed converter using one transformer has soft switching and a advantage to lower voltage stress in switch and also is predicted to have high power efficiency. we proposed the principles and theory using the zero voltage switching and verified the validity through a simulation.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.29-30
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• 2010

This paper proposed bidirectional DC-DC converter applying soft switching technique. Compared with conventional bidirectional converter, the main switches of proposed converter are operated without switching losses, and auxiliary switches were run under soft switching condition using quasi-resonant current mode. To verify the validity of the proposed converter, mode analysis and simulation results are presented.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.5
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• pp.477-483
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• 2011

Existing switching system that is one of the ways which are used for DC/DC power converter is classified to hard-switching system and resonant-soft-switching system, generally. Hard-switching system is inefficient because the power loss of the switching element is large when it is been to trun on or turn off. And resonant-soft-switching system have the defect that need to add the another reactor and capacitor that make it expensive and huge. This paper suggest the ZVS Full-Bridge power converter contrcution of novel switching system for the overcoming these shortcomings. In Suggested soft-switching system, the front of buck converter at diode current, switch is changing on and off at the part of full-bridge converter's zero voltage part. as the result that is possible to be ZVS excepting the reactor and capacitor. also to verify the reasonability of the isolated ZVS full-bridge DC/DC converter as previously suggested, we produced the 500[W] level DC/DC converter and enforced the simulation for Psim, and then it able to conform the superiority of the DC/DC converter's efficient.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.4
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• pp.298-305
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• 2012

This paper proposes a soft switching boost converter with an auxiliary resonant circuit. The auxiliary resonant circuit is added to a general boost converter and that is composed of one switch, one diode, one inductor and two capacitors. The resonant network helps the main switch to operate with a zero voltage switching(ZVS) and auxiliary switch also operates under the zero voltage and zero current conditions. The soft switching range is extended by the auxiliary switch and it is possible to control the proposed converter with a pulse width modulation(PWM). The ZVS and ZCS techniques make switching losses decreased and efficiency of the system improved. A theoretical analysis is verified through the simulation and experiment.

• Journal of IKEEE
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• v.13 no.4
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• pp.82-88
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• 2009

This paper is analyzed for a step up-down DC/DC chopper of high efficiency added electric isolation. The converters of high efficiency are generally made that the power loss of the used semiconductor switching devices is minimized. To achieve high efficiency system, the proposed chopper is constructed by using a partial resonant circuit. The control switches using in the chopper are operated with soft switching by partial resonant method. The control switches are operated without increasing their voltage and current stresses by the soft switching technology. The result is that the switching loss is very low and the efficiency of the chopper is high. The proposed chopper is also added electric isolation which is used a pulse transformer. When the power conversion system is required electric isolation, the proposed chopper is adopted with the converter system development of high efficiency. The soft switching operation and the system efficiency of the proposed chopper are verified by digital simulation and experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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• pp.312-321
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• 2013

In this paper, high efficiency control method for flyback inverter with synchronous rectifier(SR) based on photovoltaic AC modules is proposed. In this control method, the operation of SR is classified according to the voltage spike across main switch SP. When the voltage spike across SP is lower than the rating voltage of SP, the operation of active clamp circuit is interrupted for reducing the switching loss of auxiliary switch. In this time, the SR is operated for soft-switching of SP. When the voltage spike across Sp is higher than the rating voltage of SP, the operation of active circuit is activated for reducing the voltage spike. The SR is operated for reducing the conduction loss of secondary output diode. Thus, a switching loss of the main switch can be reduced in low power region, and weighted-efficiency can be improved. A theoretical analysis and the design principle of the proposed method are provided. And validity is confirmed through simulation and experimental results.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.9
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• pp.118-125
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• 1997

This paper proposed a new partial resonant 3.PHI. AC-DC boost converter of high efficiency using lossless snubber. The proposed converter, DCM (Discontinuous Current Mode) has a merit of simple controlled circuit because the input current control discontinuously. But turned off switching loss and stress of the switching device increase when the switch turned off at the peak of current. Therefore, the paper improves efficiency by adopting the PRS$^{2}$(Partial Resonant Soft Switching) in 3.PHI. AC-DC boost converter and makes the unity power factor. The PRS$^{2}$ is reduced a current/voltage stresses of switching devices. Also, a DCMPRS$^{2}$M(Discontinuous Conduction Mode Partial Resonant Soft Switching Method) appear the current and voltage equation of this circuit. The paepr examine in a 3.PHI. AC-DC boost converter and show the result of that.