• Smart Structures and Systems
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• v.26 no.4
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• pp.521-531
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• 2020

In this paper, a new interleaved high step-up converter with low voltage stress on the switches is proposed. In the proposed converter, soft switching is provided for all switches by just one auxiliary switch, which decreases the conduction loss of auxiliary circuit. Also, the auxiliary circuit is expanded on the converter with more input branches. In the converter all main switches operate under zero voltage switching condition and auxiliary switch operate under zero current switching condition. Because of the interleaved structure, the reliability of converter increases and input current ripples decreases. The clamp capacitor in the converter not only absorb the voltage spikes across the switch due to leakage inductance, but also improve voltage gain. The proposed converter is fully analyzed and to verify the theoretical analysis, a 100 W prototype was implemented. Also, to show the effectiveness of auxiliary circuit on conduction EMI, EMI of the proposed converter comprised with hard switching counterpart.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2039-2041
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• 1998

In this paper, Operation characteristics of the active clamp(ACL) zero-voltage-switching(ZVS) forward converter(FC) and active clamp hard- switching(HS) forward converter are compared with respect to loss analysis. The losses of semiconductor (including conduction losses and switching losses), transformer(containing the core loss and copper loss) and parasitic element of passive element (capacitor, inductor) are measured and compared for each type. For an experiment we have built 50W ACL ZVS-FC and ACL HS-FC, in which the switching frequency is 200kHz, and test it. The experimental results show that both types of operation have nearly same characteristics.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.3-5
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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.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.1
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• pp.10-17
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• 2002

Due to the development of information communication field, the interest of the SMPS(Switched Mode Power Supply) is increased. The size and weight of SMPS are decided by inductor, capacitor and transformer. Thus, the low loss converter which is operated in high speed switching is required. The resonant FB DC-DC converter is able to operate in high speed switching and apply to high power field because the switching loss is low. In this thesis, it is proposed to control strategy for constant output power of resonant FB DC-DC converter in variable input voltage. The proposed control system is a digital I-PD type control and apply to phase-shift resonant type controller. The output voltage tracks reference without steady state error in variable input voltage. The validity of proposed control strategy is verified from results of simulation and experiment.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1998.11a
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• pp.120-124
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• 1998

In this paper, new zero voltage and zero current switched PWM(Pulse Width Modulated) converters are suggested. The main and auxiliary switch of the converters satisfy soft switching conditions, which are zero voltage or zero current switching of the switches. The switching characteristics of the proposed converters are experimentally verified by boost typed converter, which has 250 kHz switching frequency. For the 250 kHz operation, turn on period of auxiliary switch is about 1/40 for switching period of 4 ${\mu}\textrm{s}$. Therefore, the conduction loss of auxiliary switch is reduced.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.713-718
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• 1998

Due to high power ratings and low conduction loss, the IGBT has become more attractive in high power applications. However, its slower characteristics than those of MOSFET cause severe switching losses and switching frequency limitation. This paper proposes the IGBT's soft switching concept with the help of MOSFET, where each of the IGBT and MOSFET plays its role during on-periods and switching instants. Also, the switching losses are analyzed by using the linearized modeling and the modeling and the operations of a converter are investigated to confirm the soft switching of IGBT's.

• Journal of Power Electronics
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• v.15 no.3
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• pp.685-694
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• 2015

The power loss of the controllable switches in modular multilevel converter (MMC) HVDC transmission systems is an important factor, which can determine the design of the operating junction temperatures. Due to the dc current component, the approximate calculation tool provided by the manufacturer of the switches cannot be used for the losses of the switches in the MMC. Based on the enabled probabilities of each SM in an arm, the current analytical models of the switches can be determined. The average and RMS currents can be obtained from the corresponding current analytical model. Then, the conduction losses can be calculated, and the switching losses of the switches can be estimated according to the upper limit of the switching frequency. Finally, the thermal resistance model of the switches can be utilized, and the junction temperatures can be estimated. A comparison between the calculation and PSCAD simulation results shows that the proposed method is effective for estimating the junction temperatures of the switches in the MMC.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.143-146
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• 2002

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-ed 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.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1187-1189
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• 2002

In the case of an existing high frequency inverter is became forced extinction by quick load change, due to be connected with series inductor on switch, it is destroyed or is generated conduction loss by resistance component in reactor. And, In the operation of high current with a soft switching, conduction loss can not neglect. In this paper, for the high current power source, we make sure of soft swtching operation and reducing surge when the forced extinction by using a connected switch with series inductor. Also, we poropos a topology of the half bridge type high frequency inverter that can be realized high amplitude operation of the load current. And, analyze the circuit to decide an opmtial circuit parameter.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.6
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• pp.406-410
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• 2019

Three-level (3L) DC-DC converters are appropriate for high-input-voltage applications. Although the voltage stress of TL converter switches can be reduced to half of the input voltage, the primary side has a large circulating current, which degrades efficiency. In this study, a dual half-bridge cascaded TL converter is presented to reduce this circulating current and thus decrease the conduction loss of the primary circuit. Moreover, the proposed converter can reduce the voltage stress of rectifier diodes, thereby reducing their conduction loss. Therefore, efficiency can be improved by reducing the conduction loss of the primary circuit and rectifier diodes.