• International journal of advanced smart convergence
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• v.9 no.2
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• pp.105-113
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• 2020

In this paper, we proposed a soft switched synchronous boost converter, which can perform discharging the battery, is proposed. The proposed converter has low switching loss even at high frequency operation due to its soft switching characteristics. The converter operates in synchronous mode to minimize conduction loss because of changing the rectified diode to MOSFET with a low on resistance. In this reason, the efficiency of the converter can be greatly improved in high frequency. In this paper, the battery discharger with a switching frequency of 100 kHz, has been designed. The designed converter also simulated to prove the converter's characteristics of synchronous operation as well as soft switching operation. The simulation shows that the proposed converter always meets the soft switching conditions of turning on and off switching in the zero voltage and zero current states. Therefore, simulation results have confirmed that the proposed battery discharge had soft switching characteristics. The simulation results have confirmed that the proposed battery discharger had soft switching and synchronous operation characteristics.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.577-595
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• 2017

${\bullet}$ Silicon Carbide (SiC) had excellent material properties as the base material for next generation of power semiconductor. In developing SiC MOSFET, gate oxide reliability issues had to be first overcome before commercial application. Besides, a high and stable gate-source voltage threshold $V_{GS(th)}$ is also an important parameter for operation robustness. SiC MOSFET with such characteristics can directly use existing high-speed IGBT gate driver IC's. ${\bullet}$ The linear voltage drop characteristics of SiC MOSFET will bring lower conduction loss averaged over full AC cycle compared to similarly rate IGBT. Lower switching loss enable higher switching frequency. Using package with auxiliary source terminal for gate driving will further reduce switching losses. Dynamic characteristics can fully controlled by simple gate resistors. ${\bullet}$ The low switching losses characteristics of SiC MOSFET can substantially reduce power losses in high switching frequency operation. Significant power loss reduction is also possible even at low switching frequency and low switching speed. in T-type 3-level topology, SiC MOSFET solution enable three times higher switching freqeuncy at same efficiency.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.460-465
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• 1998

Due to high power ratings and low conduction loss, the IGBT has become more attractive in switching power supplies. However, its turn-on and turn-off characteristics cause severe switching loss and switching frequency limitation. This paper proposes 2.4kW, 48V, high efficiency half-bridge DC-DC converter using paralleled IGBT-MOSFET switch concept, where each of IGBT and MOSFET plays its part during on-periods and switching instants. The switching loss is analyzed by using the linearized model and the opteration of the converter are investigated by simulation results.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.117-120
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• 1996

Power conversion system must be increased switching frequency in order to achieve a small size, a light weight and a low noise. However, the switches of converter are subjected to high switching power losses and switching stresses. As a result of those, the power system brings on a low efficiency. In this paper, the authors propose a DC-DC boost converter of high power by partial resonant switch method (PRSM). The switching devices in a proposed circuit are operated with soft switching and the control technique of those is simplified for switch to drive in constant duty cycle. The partial resonant circuit makes use of a inductor using step up and a condenser of loss-less snubber. Also the circuit has a merit which is taken to increase of efficiency, as it makes to a regeneration at input source of accumulated energy in snubber condenser without loss of snubber in conventional circuit. The result is that the switching loss is very low and the efficiency of system is high. The proposed converter is deemed the most suitable for high power applications where the power switching devices are used.

• International journal of advanced smart convergence
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• v.8 no.4
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• pp.138-146
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• 2019

In this paper, we proposed a soft-switched synchronous buck converter, which can perform charging the battery. The proposed converter has low switching loss even at high frequency operation due to its soft switching characteristics. The converter operates in synchronous mode to minimize conduction loss, resulting in small conduction loss, also. In this reason, the efficiency of the converter can be greatly improved even in high frequency. The size and weight of the converter can be reduced by high frequency operation of the converter. In this paper, we designed a battery charger with a switching frequency of 100 kHz. The designed converter also simulated to prove the converter's characteristics of synchronous operation as well as soft switching operation. The simulation shows that the proposed converter always meets the soft switching conditions of turning on and off switching in the zero voltage and zero current states. Therefore, simulation results have confirmed that the proposed battery charger had soft switching characteristics. The simulation results for transient response to charge current for the designed converter show that the converter responds to charge current commands quickly within 0.05 ms.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1148-1150
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• 2003

Power conversion system must be increased switching frequency in order to achieve a small size, a light weight and a low noise. However, the switches of converter are subjected to high switching power losses and switching stresses. As a result of those, the power system brings on a low efficiency. To improved these, a large number of soft switching topologies included a resonant circuit has been prosed. But these circuits increase number of switch in circuit and complicate sequence of switching operation. In this paper, the authors propose a high power factor and high efficiency DC-DC converter using single-pulse soft switching by partial resonant switching node. The switching devices in a prosed circuit are operated with soft switching by the partial resonant method, that is, Partial Resonant Switch Mode Power Converter. The partial resonant circuit makes use of a inductor using step up and a condenser of loss-less snubber. The result is that the switching loss is very low and the efficiency of system is high. Also the proposed converter is deemed the most suitable for high power applications where the power switching devices are used. Some simulative results on computer results are included to confirm the validity of the analytical results.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1049-1050
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• 2006

This paper is proposed to a novel DC-DC converter operated high efficiency for loss-less snubber capacitor. The general converters of high efficiency is made that the power loss of the used switching devices is minimized. To achieve the soft switching operation of the used control switches, the proposed converter is constructed by using a loss-less snubber capacitor. The proposed converter achieves the soft-switching for all switching devices without increasing their voltage and current stresses. The result is that the switching loss is very low and the efficiency of converter is high. The soft switching operation of the proposed converter is verified by digital 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 KIEE Conference
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• 2000.07b
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• pp.1193-1195
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• 2000

In conventional zero-current-switching(ZCS) PWM converters, the switching loss, stress and noise can't be minimized because they adopt auxiliary switches operated in hard-switching. In this paper, new ZCS-PWM converters of which auxiliary switches always operate with soft-switching are proposed. Therefore, the proposed ZCS-PWM converters are most suitable for systems requiring high-power density. The characteristics of these converters are verified by results of simulation.

• Journal of Power Electronics
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• v.9 no.2
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• pp.259-266
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• 2009

In order to increase the power density of power converters, reduction of the switching losses at high-frequency switching conditions is one of the most important issues. This paper presents a new gate drive circuit that enables the reduction of switching losses in both the Power MOSFET and the IGBT. A distinctive feature of this method is that both the turn-on loss and the turn-off loss are decreased simultaneously without using a conventional ZVS circuit, such as the quasi-resonant adjunctive circuit. Experimental results of the switching loss of both the Power MOSFET and the IGBT are shown. In addition, an energy recovery circuit suitable for use in IGBTs that can be realized by modifying the proposed gate drive circuit is also proposed. The effectiveness of both the proposed circuits was confirmed experimentally by the buck-chopper circuit.