• 전기학회논문지
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• 제67권12호
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• pp.1602-1610
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• 2018

Induction heating can convert electrical energy to thermal energy with high conversion efficiency and quick heating. Currently, a current source rectifier/inverter-fed parallel resonant circuit is widely used as an induction heating power supply for forging applications. However, the conventional induction heating power supplies composed of phase-controlled rectifier and SCR inverter have low efficiency and low power factor at input side, and require additional starting circuitry. So this paper proposes new induction heating power supply topologies for forging applications which have high power factor, high efficiency, and large output power. It also suggests detailed design guideline.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.413-415
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• 1997

The solar cell has an optimum operating point to be able to get maximum power. To obtain maximum power from Photovoltaic array, potovolt aic power syste usually requres maximum power point tracking controller. The output characteristics of solar cell are nonlinear, and these characteristics vary with load solar insolation, solar cell temperature. Therefore the tracking control of maximum power point is the complicated problem. This paper presents power characteristics of residential Photovoltaic system applying a quck-boost conversion system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 추계학술대회 논문집
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• pp.115-117
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• 2007

This paper is analyzed for DC-DC chopper performance of high efficiency added in electric isolation. The general converters of high efficiency are made that the power loss of the used 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 for a 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 chopper is high. And the proposed chopper is added in a electric isolation. When the power conversion system is required to electric isolation, the proposed chopper is adopted with system development of high efficiency. The soft switching operation and the system efficiency of the proposed chopper is verified by digital simulation and experimental results.

• 전력전자학회논문지
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• 제23권3호
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• pp.182-189
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• 2018

LLC resonant converters or phase-shift full-bridge converters have been widely used as DC - DC converters for rapid charging of electric vehicles (EVs). However, these converters present critical disadvantages, including a large circulating current, which can hinder efficiency and miniaturization in EV battery charger applications. In this paper, a new DC - DC converter topology is proposed for EV rapid chargers. The proposed converter can operate at high frequency despite a high rated power capacity of over 20kW, and the problem of circulating current can be minimized during the entire battery charging time. Owing to these advantages, the proposed converter can achieve a high conversion efficiency of over 97% for EV rapid charger applications. The performance of the proposed converter is verified with 20kW prototypes in this study.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.15-16
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• 2010

This paper is study on a high efficiency DC-DC converter of discontinuous conduction mode (DCM) added electric isolation. The converters of high efficiency are generally made that the power losses of the used semiconductor switching devices is minimized. To achieve high efficiency system, the proposed converter is constructed by using a quasi resonant circuit. The control switches using in the converter are operated with soft switching by quasi 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 system is high. The proposed converter is also added electric isolation which is used a pulse transformer. When the power conversion system is required electric isolation, the proposed converter is adopted with the converter system development of high efficiency. The soft switching operation and the system efficiency of the proposed converter are verified by digital simulation and experimental results.

• 조명전기설비학회논문지
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• 제12권1호
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• pp.51-57
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• 1998

본 논문은 구동신호 위상제어 기능을 갖는 SIT고주파공진 인버터를 제안하였다. SIT를 이용한 위상제어형인버터는 낮은 스위칭 손실로서 높은 스위칭 주파수의 전력변환을 실현시킬 수 있다. 특히 2단위 인버터의 출력전압을 직렬로 연결하여 높은 출력을 얻을 수 있다. 과전류에 대해서 보호회로를 이용한 시스템의 안정성과 그리고 PLL에 의해 부하변화에 따른 자동추종제어를 실현하였다. 특히 제안된 인버터는 고주파에서도 거의 정현파에 가까우며, 스위칭 주파수 범위는 180∼220〔kHz〕이고, 2〔kW〕의 유도가열에 응용하였다. 본 인버터의 동작 특성에 대해서 이론과 실험결과를 비교 검토하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.40-41
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• 2016

The inverter resistance welder requires AC/DC converter of high efficiency because the converter changes a commercial ac power source to low voltage dc power source. Harmonic components that occur in the conversion process of converter decrease system power factor and deal great damage in electric power system. To improve such problems, this paper proposes a high efficiency AC/DC converter for inverter resistance welder. The switching devices in the proposed converter are operated by soft switching technique using a new quasi-resonant circuit. As a result, the proposed AC/DC converter obtains low switching power loss and high efficiency.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.413-417
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• 1998

In order to obtain better performance for a SRM(switched reluctance motor) drive, the commutation from one phase to another must be as fast as possible. In this paper a novel converter for SRM drive is proposed, which can accelerate the turn-off and turn-on time by using two capacitors to form a resonant circuit with the motor inductance. Two capacitors recover rapidly stored energy in the off going phase and establish rapidly the current rising in the on going phase. As a result, the current tail can be shortened and the dwell angle in the positive torque region can be extended. And comparing with the asymmetric converter, this converter has higher energy availability in energy conversion process and less number of switches.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.348-350
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• 2008

A link voltage adjustment converter employing load power estimator for notebook computer adaptor is proposed. It is consisted of the boost converter as a power factor correction stage and the LLC resonant converter as a DC/DC conversion stage with a newly introduced link voltage adjustment method employing load power estimator, which helps to reduce the transformer size and peak of output voltage ripple, maintaining high efficiency over all the load condition. Experimental results with 85W converter are given to verify the validity of the proposed circuit.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.382-384
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• 2008

Hold-up time is a special requirement for the front end DC/DC converter in a server power supply. It forces the converter with the variable switching frequency to operate in a wide switching frequency range, which makes the regulation difficult and reduces the power density. In this paper a novel frequency controlled half bridge converter with the hold-up time extension circuit is proposed. During the hold-up time, the auxiliary switches are turned on, thus the resonant inductance is reduced and the voltage conversion ratio is increased. Therefore, the output capacitor of the power factor correction (PFC) circuit can be decreased, and the converter can have high power density. The proposed converter is verified by experimental results from a prototype with 700W, 400V input, and 12V output.