• Journal of IKEEE
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• v.24 no.3
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• pp.677-684
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• 2020

In this paper, the energy efficiency of a 4H-SiC UMOSFET with a local floating superjunction (LFS UMOSFET) was compared with a conventional P-shielding UMOSFET. For analysis, P-shielding UMOSFET and LFS UMOSFET were modeled for energy loss and junction temperature. As a result, LFS UMOSFET showed switching loss reduction of 20.6%. In addition, it was confirmed that LFS UMOSFET is applied to a 3-phase inverter, resulting in 33.2% lower power efficiency and 28.1% lower junction temperature than P-shielding UMOSFET. Electrical characteristics were simulated using Sentaurus TCAD, and the power circuit was simulated with the modelled UMOSFET using PSIM, a power circuit simulator.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.5
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• pp.394-399
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• 2007

In this paper, we study on a novel Buck-Boost converter of high efficiency by soft switching method. The proposed Buck-Boost converter is applied to new soft switching method in restraint of increment of switching power loss in the conventional Buck-Boost converter. The soft switching circuit is designed to modification of a energy storage inductor and a snubber circuit used by the conventional converter, and then the proposed converter is simplified. The controlling switches of the proposed converter is operated with soft switching by a partial resonance behavior. The output voltage of the converter is regulated by PWM control technique. The discontinuous mode action of current flowing into inductor makes to simplify control method and control components. The proposed Buck-Boost converter is compared with the conventional converter. Some computer simulative results and experimental results are confirmed to the validity of the analytical results.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.342-345
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• 1999

This paper describes a current regulated PWM boost type rectifier based on modified trapezoidal PWM. Each switch of a converter has no switching for one third period of a fundamental line current. Therefore, the switching loss of the proposed scheme is less than that of the hysteresis current controller. Operating principle is described and controller. Operating principle is described and simulations and experiments are carried out.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.159-160
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• 2015

Recently, it is increased to use the portable device with small size. It is also increasing for demand of a small size adapter. To reduce the size of components, switching frequency has to be increased. But it causes higher switching loss and temperature of components. Especially, the temperature of adapter must be limited because adapter can be easily touched when portable device is being charged. To reduce temperature of adapter, high efficiency is essential. To solve this problem, this paper proposes design of resonance frequency optimization for LLC converter with high efficiency and low temperature of passive components.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.2
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• pp.31-41
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• 2014

This paper proposes the configuration of photovoltaic(PV) module considering the environment conditions of the PV system. The PV system is consisted of the series-parallel connection of the PV module. When shadows or changes of the radiation or an electrical characteristic in the solar cell are happened to PV system, the serious power loss will occur. If the PV module connected in series has the shadows, the output current is restricted to current of shaded PV module. Also if shadow is occurred to the parallel connection PV module, the output voltage is limited to voltage of shaded PV module. These problems are caused power loss. Therefore, this paper proposes the method that makes the output power of the PV module equalize by reconfiguration of PV module using the switching considering these environment conditions. A validity of the method proposed in this paper proves through comparing with performance of conventional PV module.

• Journal of Power Electronics
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• v.11 no.4
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• pp.499-506
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• 2011

This paper presents an interleaved active-clamping zero-voltage-switching (ZVS) forward-flyback converter without an output choke. The presented topology has two active-clamping circuits with two separated transformers. Because of the interleaved operation of the converter, the output current ripple will be reduced. The proposed converter can approximately share the total load current between the two secondaries. Therefore, the transformer copper loss and the rectifier diodes conduction loss can be decreased. The output capacitor is made of two series capacitors which reduces the peak reverse voltage of the rectifier diodes. The circuit has no output inductor and few semiconductor elements, such that the adopted circuit has a simpler structure, a lower cost and is suitable for high power density applications. A detailed analysis and the design of this new converter are described. A prototype converter has been implemented and experimental results have been recorded with an ac input voltage of 85-135Vrms, an output voltage of 12V and an output current of 16A.

• Proceedings of the KIPE Conference
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• 2018.11a
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• pp.86-88
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• 2018

The three level(3L) neutral point clamped (NPC) voltage source converter (VSC) topology is widely used for grid interface in high power wind energy due to its superior performance as compared to the two level(2L) VS. However, one of the major drawbacks of this topology is the unequal dispersion of loss and therefore the junction temperature among the power devices. The 3L ANPC topology derived from the NPC topology was proposed to resolve this drawback of unequal loss profile of 3L NPC. The 3L ANPC can work under various switching strategies. In this paper a comparative study of the various switching strategies of 3L ANPC using the recently developed 10kV IGCTs which has the capability to raise the current and voltage rating of the wind turbines is carried out. The comparison is performed using ABB make 10kV IGCT 5SHY17L9000 and PLECs simulations.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.103-106
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• 2000

In this paper a communication system that is not using the communication line but power line is presented. It will be very useful for an information-oriented society with tele-metering and home automation. Conventional system has a difficulty in transmitting information due to decreasing communication voltage and increasing carrier, current. Proposed idea is a special type switching amplifier system which has a low inner resistance. It can provide reactive power and dose not have low impedance between the transceivers. This new system is proposed to overcome the loss of conductor load in a PLC system.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.27-30
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• 2003

This paper describes two novel current fed high frequency resonant inverter can be used as the power supp]y for wax-sealing. This two topology can be obtained higher output frequency than switching frequency by composing modified unit inverter based on conventional half-bridge serial resonant inverter in parallel with input power source. also, By using time-sharing gate control method, this proposed inverter can not only realize the output control of dependence irrespective of the switching frequency using phase-shift but also reduce switching loss because it has ZVS function. Simulation results through the Pspice have demonstrated the feasibility of the proposed inverter. This proposed inverter will be able to be practically used as a power supply in various fields as induction heating applications, DC-DC converter etc.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.19-22
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• 2004

The resonant planar transformer, which had power capacity of 300 W, input voltage of 220 V, output voltage of 15 V, and switching frequency of 500 kHz, was designed and manufactured by using the planar core with large effective area and the flat copper lead frames for miniaturization and high efficiency of the switching mode power supply (SMPS). As well as, a resonant converter equipped with the above mentioned planar transformer was manufactured and electromagnetic characteristics were investigated. The numerical value of turns for 1st and 2nd winding were 12 and 2 respectively. The self inductance of 1st winding was 33.2 ${\mu}H$, very low leakage inductance of 1.27 ${\mu}H$, and the coupling factor of 0.98 were obtained at switching frequency of 300 kHz. The high efficiency of 88.21 % for the SMPS equipped with planar transformer was obtained at power capacity of 300 W.