• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.352-357
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• 2003

A new single stage power factor correction(PFC) AC/DC converter based on zero voltage switching(ZVS) full bridge topology is proposed. Since the series-connected two transformers act as both output inductor and main transformer by turns, the proposed converter has a wide ZVS range without additional devices for ZVS. Furthermore, since there is no need to use an output inductor, the proposed converter features high power density. The proposed converter gives the good power factor correction and low line current harmonics distortion. A mode analysis and experiment results are presented to verify the validity of the proposed converter.

• Journal of Advanced Marine Engineering and Technology
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• 제21권2호
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• pp.178-185
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• 1997

According to the wide - spread use of rectifier in electronic equipments, such problems as electronic components failures or equipment disorders have been occurred due to current harmonics. To overcome these problems, power factor correction circuits employing boost converter have been used. The high switching stress of boost converter can be reduced by snubber circuit. Recently, research activities in snubber circuits have been directed to energy recovery snubber for improving the efficiency of power converter. In this study, a new passive snubber circuit which can recover trapped snubber energy without added control is proposed for boost converter. The control of boost converter with proposed snubber is the same as the conventional one. In addition, the energy recovery circuit can be implemented with a few passive components. The circuit operation is confirmed through simulation.

• Nuclear Engineering and Technology
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• 제47권1호
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• pp.135-138
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• 2015

A new correlation predicting the idealized critical mass-flow rates of water for subcooled and saturated liquid water including two-phase water flow was developed for a wide range of upstream stagnation pressures (e.g., 0.5-20.0 MPa). A choking correction factor dependent on the upstream stagnation pressure and subcooled temperature was introduced into a new correlation, and its values were suggested to satisfy the idealized nozzle data within 10% error ranges. The suggested correlation will be instructive and helpful for related studies and/or engineering works.

• 한국산학기술학회논문지
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• 제12권6호
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• pp.2707-2712
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• 2011

본 논문에서는 400V, 120W 급 LED 구동을 위한 1단 전류 경계모드(Boundary Condition Mode) 제어방식의 역률 개선 제어회로를 설계하였다. 제안하는 제어회로는 역률 개선 및 고조파 발생을 감소시키는 기능을 가지고 있으며, 또한 PFC(Power Factor Correction)회로 내에서 상대적으로 많은 면적을 차지하는 기존의 바이폴라 트랜지스터 구조 대신 새로운 CMOS 회로로 설계하였다. 기존대비, 약 30% 정도의 레이아웃 면적을 줄이게 되었고, 상용화 시 칩의 가격 경쟁력이 클 것으로 사료된다.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3488-3493
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• 2022

Accelerator driven subcritical systems have long been discussed as facilities which can be used for solving the nuclear waste problem. The physics of these systems is very different from conventional reactors and new techniques had to be developed for reactivity monitoring. One such technique is the Area Ratio Method which studies the response of a subcritical system upon insertion of a large number of neutron pulses. An issue associated with this technique is the spatial dependence of measured reactivity which is intrinsic to the sub criticality of the system since the reactor does not operate on the fundamental mode and measured reactivity depends on the detector position. This is generally addressed by defining Bell-Glasstone spatial correction factor. This factor upon multiplication with measured reactivity gives the correct reactivity which is independent of detector location. Monte Carlo Methods are used for evaluating these factors. This paper presents a complete three dimensional map of spatial correction factors for BRAHMMA subcritical system. In addition, the dataset obtained also helps in identifying detector locations where the correction factor is close to unity, thereby implying no correction if the detector is used at those locations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.348-350
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• 1996

A new reset winding clamped forward converter with transformer voltage feedback technique for power factor correction with a single-switch/single-stage is proposed. The proposed converter gives the good power factor correction, low current harmonic distortions, and tight output voltage regulation. The prototype shows the IEC555-2 requirements are met satisfactorily with nearly unity power factor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1175-1177
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• 2003

In this paper, an application of the ZVT-PWM(zero-voltage-transition) boost converter, which has great advantage on miniaturization and high power density, to the power factor correction circuit of the EFL(electrodeless fluorescent lamp) inverter is studied. The operation principles of the converter are described to identify the power factor correction characteristic of the inverter. Experimentally obtaining the high power factor above 0.99, it is verified that the power factor correction of the EFL inverter successfully achieved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2240-2242
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• 1997

A new group of magnetic coupled high power factor converter with a single-switch /single-stage is proposed. The proposed converter gives the good power factor correction, low current harmonic distortions, and tight output voltage regulation. The prototype shows the IEC555-2 requirements are met satisfactorily with nearly unity power factor.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1539-1548
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• 2018

This paper introduces a new soft switched AC-DC boost converter with power factor correction (PFC). In the introduced converter, all devices are turned on and off under soft switching (SS). The main switch is turned on under zero voltage transition (ZVT) and turned off under zero current transition (ZCT). The main diode is turned on under zero voltage switching (ZVS) and turned off under zero current switching (ZCS). Meanwhile, there is not any current or voltage stress on the main devices. Besides, the auxiliary switch is turned on under ZCS and turned off under ZVS. The detailed theoretical analysis of the converter is presented, and also theoretical analysis is verified by a prototype with 100 kHz and 500 W. Also, the proposed converter has 99.8% power factor and 97.5% total efficiency at soft switching operation.

• Journal of Power Electronics
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• 제15권2호
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• pp.356-365
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• 2015

This paper presents a new single phase front-end ac-dc bridgeless power factor correction (PFC) rectifier topology. The proposed converter achieves a high efficiency over a wide range of input and output voltages, a high power factor, low line current harmonics and both step up and step down voltage conversions. This topology is based on a non-inverting buck-boost (Zeta) converter. In this approach, the input diode bridge is removed and a maximum of one diode conducts in a complete switching period. This reduces the conduction losses and the thermal stresses on the switches when compare to existing PFC topologies. Inherent power factor correction is achieved by operating the converter in the discontinuous conduction mode (DCM) which leads to a simplified control circuit. The characteristics of the proposed design, principles of operation, steady state operation analysis, and control structure are described in this paper. An experimental prototype has been built to demonstrate the feasibility of the new converter. Simulation and experimental results are provided to verify the improved power quality at the AC mains and the lower conduction losses of the converter.