• 조명전기설비학회논문지
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• 제19권4호
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• pp.71-78
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• 2005

본 연구는 AC PDP(Plasma Display Panel)용 멀티레벨 에너지 회수회로에 관한 연구로서, 기존 멀티레벨 구동회로의 문제점을 해결한 새로운 멀티레벨 구동회로를 제안한다. 기존 멀티레벨 구동회로는 Weber회로에서 나타나는 스위칭 소자의 전압 및 전류 스트레스를 개선하였지만 공진 인덕터와 기생 커패시턴스에 의한 기생공진전류가 존재하고 하드스위칭이 발생하며 또한 천이구간이 다소 긴 문제점이 있다. 제안 회로는 사용소자의 수를 줄여 회로를 간단히 하였으며, 기생공진전류를 제거하여 회로 동작의 안정성을 높였다. 또한 CIM(Current Injection Method) 을 사용하여 하드스위칭 문제를 해결하였으며 Vs/2 유지구간을 제거하여 동작주파수를 증가시킬 수 있도록 하였다. 제안 회로의 유용성을 입증하기 위해 모드별로 동작을 해석하였으며, PSpice프로그램을 이용하여 시뮬레이션하고 그 결과를 확인하였다.

• Journal of Power Electronics
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• 제9권1호
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• pp.18-25
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• 2009

Conventional series-resonant pulse frequency modulation controlled DC-DC high power converters with a high-frequency transformer link which is designed for driving the high power microwave generator has the problem of hard switching commutation at turn-on and turn-off of active power switching devices. This problem is due to the influence of the magnetizing current of the high-frequency transformer. This paper presents a novel prototype for a high-frequency transformer using parasitic parameters with a lossless inductive snubber and a series resonant capacitor assisted series-resonant zero current switching pulse frequency modulated DC-DC power converter, which is designed using a high power magnetron for microwave ovens. In order to implement a complete and efficient soft switching commutation, the performance of the new converter topology is practically confirmed and evaluated in the prototype of a power microwave generator.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.559-562
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• 2000

The problem of noise generation due to PWM switched-mode power converter has been widely noticed from the viewpoint of Electromagnetic Interference(EMI). Many kings of topologies for resonant converters have been developed both to overcome this noise problem and to attain high power efficiency. It is reported in references that resonant converters which are derived from PWM converter using resonant switch show much lower noise characteristics than PWM converter, and that current-mode resonant converter is more sensitive to stored charge in rectifying diode than voltage-mode counterpart concerning surge generation at diode’s turn-off. On the other hand, above mentioned resonant converters have defect of high-voltage stress on semiconductor switch and complicated circuit configuration. Hence, the simplified Forward-type resonant converter has been proposed and investigated due to its prominent features of simplicity of circuit configuration, low voltage stress and high stability. However, its noise characteristics still remain unknown. The purpose of this paper is to study quantitatively the noise characteristics of this simplified Forward-type resonant converter by experiment and analysis. The influence of parasitic elements and stored charge in rectifying diode on noise generation has been clarified.

• Journal of Power Electronics
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• 제4권1호
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• pp.46-55
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• 2004

This paper presents a high-frequency ZVS-PWM boost chopper-fed DC-DC converter with a single active auxiliary edge resonant snubber in the load-side which can be designed for power conditioners such as solar photovoltaic generation, fuel cell generation, battery and super capacitor energy storages. Its principle operation in steady-state is described in addition to a prototype setup. The experimental results of ZVS-PWM boost chopper-fed DC-DC converter proposed here, are evaluated and verified with a practical design model in terms of its switching voltage and current waveforms, the switching v-i trajectory, the temperature performance of IGBT module, the actual power conversion efficiency and the EMI of radiated and conducted emissions. And then discussed and compared with the hard switching scheme from an experimental point of view. Finally, this paper proposes a practical method to suppress parasitic oscillation due to the active auxiliary resonant switch at ZCS turn off mode transition with the aid of an additional lossless clamping diode loop, and reduced the EMI conducted emission in this paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1951-1953
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• 2004

In this study, we propose a small high voltage power supply which use a half-bridge ZCS resonant and Cockroft-Walton on circuit, for ESP (Electrostatic Precipitator). This power supply transfers energy from ZCS resonant inverter to step-up transformer and the transformer secondary is applied to the Cockroft-Walton circuit for generating high voltage as discharging source of electrodes. It is highly efficient because its amount of switching losses are reduced by virtue of the current resonant half-bridge inverter, and also due to the small size, low parasitic capacitance in the transformer stage owing to the low number of winding turns of the step up transformer secondary combined with the Cockroft-Walton circuit. From these results, the best operational condition is obtained at the switching frequency of 9 kHz and the duty ratio of 50 % in this ESP.

• 전력전자학회논문지
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• 제10권2호
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• pp.194-202
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• 2005

본 연구는 새로운 AC PDP(Plasma Display Panel)용 멀티레벨 에너지 회수회로에 관한 연구로서, 기존 멀티레벨 구동회로의 장점을 그대로 유지하면서 문제점을 해결한 새로운 멀티레벨 구동회로를 제안한다. 기존의 멀티레벨 구동회로는 Weber회로의 하드스위칭 문제를 개선하였지만 공진 인덕터에 기생공진전류가 존재하고 Vs/2유지구간이 존재한다. 제안한 회로는 기존 회로에 비해 인덕터의 수를 반으로 줄여 회로를 간단히 하고 공진 인덕터의 기생 공진전류와 Vs/2유지구간을 제거하였으며 CIM(Current Injection Method)을 사용하여 하드스위칭 문제를 해결하였다. 또한 풀브리지 구동회로에 직렬 연결된 스위칭 소자에 NPC(Neutral Point Clamping)기법을 적용하여 각 스위칭 소자에 전압이 균등하게 분배되도록 하였다. 그리고 제안회로의 동작을 모드별로 해석하였으며, PSpice 프로그램으로 시뮬레이션하고 회로를 구성하여 실험함으로써 제안한 회로의 유용성을 입증하였다.

• 전력전자학회논문지
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• 제10권3호
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• pp.274-281
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• 2005

압전소자를 에너지원으로 사용하여 자립형 전기전자시스템에 에너지를 공급하는 에너지 획득(Harvesting) 개념의 구현을 위하여, 새로운 AC/DC 공진형 펄스 컨버터를 제안한다. 컨버터는 정류기와 DC 컨버터의 2단계로 구성되었으며, AC/DC 변환을 위한 정류기는 MOSFET의 3상한 동작 특성을 이용하여 구현하고, N형 및 P형 MOSFETs을 사용하여 DC/DC 부스트 컨버터를 구현하였다. 제안된 컨버터 시스템의 동작원리 및 동작모드를 스위칭 소자의 기생캐패시턴스를 고려하여 해석하고, 시뮬레이션을 통하여 해석결과를 검증하였다. CMOS IC 칩으로 제작된 본 시스템의 실험 결과는 수십 uW 용량에서 에너지 획득 개념의 구현 가능성을 제시하였다.

• Journal of Magnetics
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• 제16권3호
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• pp.246-252
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• 2011

A high-voltage power supply has been built for activation of the brain via stimulation using a Full Wave Cockroft-Walton Circuit (FWCW). A resonant half-bridge inverter was applied (with half plus/half minus DC voltage) through a bidirectional power transistor to a magnetic stimulation device with the capability of producing a variety of pulse forms. The energy obtained from the previous stage runs the transformer and FW-CW, and the current pulse coming from the pulse-forming circuit is transmitted to a stimulation coil device. In addition, the residual energy in each circuit will again generate stimulation pulses through the transformer. In particular, the bidirectional device modifies the control mode of the stimulation coil to which the current that exceeds the rated current is applied, consequently controlling the output voltage as a constant current mode. Since a serial resonant half-bridge has less switching loss and is able to reduce parasitic capacitance, a device, which can simultaneously change the charging voltage of the energy-storage condenser and the pulse repetition rate, could be implemented. Image processing of the brain activity was implemented using a graphical user interface (GUI) through a data mining technique (data mining) after measuring the vital signs separated from the frequencies of EEG and ECG spectra obtained from the pulse stimulation using a 90S8535 chip (AMTEL Corporation).

• 한국전자파학회논문지
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• 제14권4호
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• pp.384-392
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• 2003

본 연구에서는 유전체 슬랩으로 덮힌 평행평판 도파관의 좁은 슬릿을 통한 유전체슬랩 위의 도체 스트립과의 전자기적인 결합을 고려하였다. 제안된 구조에서 관찰되는 두 가지의 대조적인 결합현상인 캐비티형 결합과 기생형 결합의 차이점을 도체 스트립의 길이 및 위치, 도체 스트립에 유기된 전류, 복사패턴, 대역폭, 결합슬릿 근처의 전자계분포 등을 비교하여 관찰하였다.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권4호
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• pp.123-129
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• 2003

We propose a high voltage dc-dc converter for a CW (continuous wave) $CO_2$ laser system using a current resonant half-bridge inverter and a Cockcroft-Walton circuit. This high voltage power supply includes a 2-stage voltage multiplier driven by a regulated half-bridge series resonant inverter. The inverter drives a step-up transformer and the secondary transformer is applied to the voltage multiplier. It is highly efficient because of the reduced amount of switching losses by virtue of the current resonant half-bridge inverter, and also due to the small size, low parasitic capacitance in the transformer stage owing to the low number of winding turns of the step up secondary transformer combined with the Cockroft-Walton circuit. We obtained a maximum laser output power of 44 W and a maximum system efficiency of over 16%.