• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.2
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• pp.131-137
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• 1999

New zero voltage switched(ZVS) converter in which main switch is switched at zero voltage is proposed. A resonant inductor of conventional ZVS PW converter is replaced to two small saturable inductors in order to reduce conduction loss of auxiliary switch. Therefore, the switching loss of main switch is very low, and conduction losses of the main and auxiliary switch are lowered. The ZVS and above characteristics are verified by experimental results for a 200 kHz operation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.361-364
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• 2013

Since the non-overlapping gate driver used in conventional DC-DC boost converters generates fixed dead-times, the converters suffer from the body-diode conduction loss or the charge-sharing loss. A adaptive control method has been proposed to reduce these loses. In this method, however, occurrence of and overlapping time of two power transistors in CCM results in reduction of efficiency. In this paper, to overcome this problem a new adaptive control method in proposed, and a DC-DC boost converter with the proposed adaptive control and power switching has been designed in a 0.35um CMOS process. The designed converter outputs 3.3V from a input voltage of 2.5V. The switching frequency is 500kHz and the maximum power efficiency is 95.3% at a load current 150mA. The designed chip area is $1720um{\times}1280um$.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1064-1066
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• 2002

This paper proposes a new prototype auxiliary resonant DC link(ARDCL)snubber circuit and deals with its power loss on the basis of actually measured conduction loss characteristic of switching device module. Voltage type soft switching three phase inverter using proposed ARDCL snubber circuit is presented along with its performance evaluations. And, the power loss analysis of three phase hard and soft switching inverter are carried out from the point of simulation and experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.4
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• pp.100-105
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• 2003

This paper proposes a new auxiliary resonant DC link(ARDCL)snubber circuit and deals with its power loss on the basis of actually-measured conduction loss characteristic of switching device module. Voltage-fed soft switching three-phase inverter using proposed ARDCL snubber circuit is presented along with its performance evaluations. And, the power loss analysis of three-phase hard and soft switching inverter are carried out from the point of simulation and experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.2
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• pp.152-158
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• 1999

Due to high power ratings and low conduction loss, the TGBT has become more attractive in switching power supplies. However, its lower turn-on and turn-off characteristics than those of MOSFET cause severe switching loss and s switching frequency limitation. This paper proposes 2.4kW. 48V. high efficiency half-bridge DC-DC converter using p paralleled TGBT-MOSFET switch concept to use the merits of TGBTs and MOSFETs. Tn parallel switches. each of I TGBT and MOSFET plays its part during on-periods and switching instants. The switching loss is analyzed by l linearized modelling and the operation of the converter are investigated by simulation results.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.477-483
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• 2010

This paper is studied on a novel buck-boost isolated converter for high efficiency and high power factor. The switching devices in the proposed converter are operated by soft switching technique using a new quasi-resonant circuit, and are driven with discontinuous conduction mode (DCM) according to pulse width modulation (PWM). The quasi-resonant circuit makes use of a step up-down inductor and a loss-less snubber capacitor. The proposed converter with DCM also simplifies the requirement of control circuit and reduces a number of control components. The input ac current waveform in the proposed converter becomes a quasi sinusoidal waveform in proportion to the magnitude of input ac voltage under constant switching frequency. As a result, it is obtained by the proposed converter that the switching power losses are low, the efficiency of the converter is high, and the input power factor is nearly unity. The validity of analytical results is confirmed by some simulation results on computer and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.9
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• pp.467-472
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• 2001

In conventional zero-current-switching(ZCS) PWM converters, zero-current turn-off for main switch without increasing voltage/current stresses is achieved at a fixed frequency. The switching loss, stress, and noise, however, can\`t be minimized because they adopt auxiliary switches turned off and main switches turned on under hard-switching condition. In this paper, new ZCS-PWM converters of which all switches are always operating with soft-switching condition are proposed. Therefore, the proposed ZCS-PWM converters are most suitable for systems requiring high-power density Breadboarded ZCS-PWM boost converters using power MOSFET are constructed to verify theoretical analysis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.1
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• pp.36-44
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• 2014

The conventional central photo voltaic inverters have several problems. First, shadow problem in each solar panel, and high DC voltage problem from each panel because of concentration to one central inverter. Therefore, module integrated inverter is proposed to solve these problems. The inverter should be small and cost effective. The cost and size in the inverter depend on the inductor. So the switching frequency should be increased to reduce the inductor and total size, but there is a problem in efficiency because of the losses in turn-on and turn-off. In the paper, the critical conduction mode(CRM) switching method is adopted to reduce the switching loss and interleaving method is proposed to increase the efficiency in Flyback converter. Finally, the validity of the proposed scheme is investigated with simulated and experimental results for a prototype system rated at 200W.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.946-949
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• 2001

This paper proposes a new zero-current switching (ZCS) pulse-width modulation (PWM) switch cell that has no additional conduction loss of the main switch. In this cell, the main switch and the auxiliary switch turn on and turn off under zero current condition. The diodes commutate softly and the reverse recovery problems are alleviated. The conduction loss and the current stress of the main switch are minimized, since the resonating current for the soft switching does not flow through the main switch. Based on the proposed ZCS PWM switch cell, a new family of dc to dc PWM converters is derived. The new family of ZCS PWM converters is suitable for the high power applications employing IGBTs. Among the new family of dc to dc PWM converters, a boost converter was taken as an example and has been analyzed. Design guidelines with a design example are described and verified by experimental results from the 2.5 kW prototype boost converter operating at 40kHz.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.520-524
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• 2001

Recently, the demand of large capacity SMPS for industrial area is increasing. Full-bridge dc-dc converter with IGBT is most widely used for large capacity SMPS because IGBT has a low-conduction loss and large current capacity, But most large capacity Full-bridge do-dc converter using IGBT has low operating frequency because of switching loss at IGBT especially at turn-off by current tail and it's cause of relatively big converter size. MOSFET has low switching losses has been widely used for high frequency SMPS but it has a problem to apply to large capacity SMPS because it has large conduction resistance causing large on-time losses. In this paper, for reduction losses at switching device, MOSFET is applied at parallel with IGBT in full-bridge dc/dc converter.