• 전력전자학회논문지
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• 제14권1호
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• pp.38-45
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• 2009

일정 출력을 얻기 위해 동기발전기 계자 여자는 AVR에 의해 제어된다. 대부분의 선박용 동기발전기 AVR은 사이리스터 위상제어 방식을 사용한다. 하지만 이 방식은 제어 주기가 MOSFET이나 IGBT로 구성된 컨버터에 비해 느리므로 속응 제어를 구현하는데 어려움이 있다. 따라서 본 논문에서는 선박용 동기발전기에 MOSFET을 사용한 PMG형 디지털 AVR을 구현하였다. PMG형 디지털 AVR 회로 구성은 간단하고 단락 시 발전기 출력전압이 영으로 되어 AVR이 동작하지 못하므로 출력전류를 여자회로로 흐르도록 하는 CBC가 요구된다. 본 논문에서 연구된 여자 시스템은 실제 선박용 발전기를 대신하여 10[kVA]급 프로토타입의 실험을 통하여 시스템의 타당성을 검증하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.227-230
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• 2003

In this paper, a full bridge edge-resonant zero voltage mode based soft-switching PWM DC-DC power converter with a high frequency center tapped transformer link stage is presented from a practical point of view. The power MOSFETS operating as synchronous rectifier devices are implemented in the rectifier center tapped stage to reduce conduction power losses and also to extend the transformer primary side power MOSFETS ZVS commutation area from the rated to zero-load without a requirement of a magnetizing current. The steady-state operation of this phase-shift PWM controlled power converter is described in comparison with a conventional ZVS phase-shift PWM DC-DC converter using the diodes rectifier. Moreover, the experimental results of the switching power losses analysis are evaluated and discussed in this paper. The practical effectiveness of the ZVS phase-shift PWM DC-DC power converter treated here is actually proved by using 2.5kW-32kHz breadboard circuit. An actual efficiency of this converter is estimated in experiment and is achieved as 97$\%$ at maximum.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2441-2446
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• 2018

This paper presents a radio frequency-to-direct current (RF-to-DC) converter for special RF power harvesting application at 915 MHz. The major featured components of the proposed RF-to-DC converter is the combination of a cross-coupled rectifier and an active diode: first, the cross-coupled rectifier boosts the input voltage to desired level, and an active diode blocks the reverse current, respectively. A prototype was implemented using $0.18{\mu}m$ CMOS technology, and the performance was proven from the fact that the targeted RF harvesting system's full-operation with higher power efficiency; even if the system's input power gets lower (e.g., from nominal 0 to min. -12 dBm), the proposed RF-to-DC converter constantly provides 1.47 V, which is exactly the voltage level to drive follow up system components like DC-to-DC converter and so on. And, maximum power conversion efficiency is 82 % calculated from the 0 dBm input power, 2.3 mA load current.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(1)
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• pp.341-345
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• 2004

A high efficiency and low device stress voltage and current clamping BVS PWM asymmetrical half bridge converter is proposed in this paper. To achieve the ZVS of power switches along the wide load range, the transformer leakage inductor $L_{Ikg}$ is increased. Then, to solve the problem related to ringing in the secondary rectifier caused by the resonance between $L_{Ikg}$ and rectifier junction capacitors, the proposed converter employs a voltage and current clamping cell, which helps voltages and currents of rectifier diodes to be clamped at the output voltage and output current, respectively. Therefore, no RC-snubber for rectifier diodes is needed and a high efficiency as well as low noise output voltage can be realized. In addition, since all energy stored in $L_{Ikg}$ is transferred to the output side, the circulating energy problem can be effectively solved and duty loss does net exist. The operational principle, theoretical analysis, and design considerations are presented. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 425W, 385-170Vdc prototype are presented.

• 조명전기설비학회논문지
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• 제29권2호
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• pp.19-26
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• 2015

This paper presents design, fabrication, and performance evaluation of a high voltage power supply for Carbon Nano Tube-based planar light sources. The proposed power supply employs an LLC resonant half-bridge converter and a sixfold voltage-multiplying rectifier. Steady-state characteristics of the voltage-multiplying rectifier are analyzed and used to derive the input-to-output voltage conversion ratio of the power supply. The input-to-output frequency response characteristics of the LLC tank circuit are analyzed and utilized in designing a proto-type power supply which produces a 15 KV output using a 400 V input source. The high-voltage transformer is fabricated using a sectional bobbin structure with an epoxy impregnation, in order to provide sufficient insulation for high voltage operations. The performance of the proposed power supply is confirmed with stable and reliable operations at the 15 KV output from no load to nominal load conditions. The proposed power supply is well suited as an electric ballast required stable operations of Carbon Nano Tube-based planar light sources.

• 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.

• 전기학회논문지
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• 제58권10호
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• pp.1947-1953
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• 2009

Metal halide (MH) lamps have been largely used due to high luminous efficiency, good color rendering, and long life. Since the metal halide lamps have problems of high ignition voltage and acoustic resonance. Thus, the design of ballast is very difficult for engineers. This paper proposes prototype of electric ballast in order to solve above two problems. The proposed electric ballast is consisted of EMI filter, full wave rectifier circuit, active PFC, DBI(Dual Buck Inverter), dimming circuit and ignitor circuit. The DBI supplies both rectangular voltage and current to the lamp. As the result of the experiment, the acoustic resonance was eliminated and the ignitor circuit was designed to generate high ignition voltage than 5kV. It makes the dimming circuit possible to control the lamp power in range between 230W and 350W.

• 한국정보통신학회논문지
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• 제4권4호
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• pp.817-824
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• 2000

본 논문은 절연변압기를 사용하지 않는 하이브리드 멀티레벨 PWM 정류기(특히 5-레벨)의 회로 DQ 모델링 및 동작특성 해석에 대한 연구이다. 회로 DQ 변환은 동기속도로 회전하는 변환 행렬을 사용함으로써 3상 시변 회로를 정지된 등가회로로 변환한다. 이러한 회로 DQ 변환을 통해 얻은 등가회로를 사용하여 시스템의 동작 특성 및 유용한 설계식들을 보다 쉽게 얻을 수 있다. 즉, 각 DC 커패시터 전압 및 전원이 공급하는 유효전력, 무효전력과 제어변수의 해석적인 식들을 보이고, 나아가 멀티레벨 출력을 얻기 위한 각 DC 전압들을 AC 전원으로부터 직접 build-up 할 수 있음을 제시한다. 또한 5-레벨 출력전압을 보장하기 위한 제어식을 유도한다. 끝으로, 이러한 모델링 및 해석의 타당성을 검증하기 위하여 MATLAB을 사용한 모의 실험을 행하고, 해석적인 예측과 모의실험으로 얻어진 파형의 일치성을 확인하였다.

• Journal of Power Electronics
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• 제3권4호
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• pp.249-258
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• 2003

This paper presents a high-efficient and cost effective three-phase AC/DC-DC/AC power conversion system with a single two-switch type active Auxiliary Resonant DC Link (ARDCL) snubber circuit, which can minimize the total power dissipation. The active ARDCL snubber circuit is proposed in this paper and its unique features are described. Its operation principle in steady-state is discussed for the three phase AC/DC-DC/AC converter, which is composed of PWM rectifier as power factor correction (PFC) converter, sinewave PWM inverter. In the presented power converter system not only three-phase AC/DC PWM rectifier but also three-phase DC/AC inverter can achieve the stable ZVS commutation for all the power semiconductor devices. It is proved that the proposed three-phase AC/DC-DC/AC converter system is more effective and acceptable than the previous from the cost viewpoint and high efficient consideration. In addition, the proposed two-switch type active auxiliary ARDCL snubber circuit can reduce the peak value of the resonant inductor injection current in order to maximize total system actual efficiency by using the improved DSP based control scheme. Moreover the proposed active auxiliary two-switch ARDCL snubber circuit has the merit so that there is no need to use any sensing devices to detect the voltage and current in the ARDCL sunbber circuit for realizing soft-switching operation. This three-phase AC/DC-DC/AC converter system developed for UPS can achieve the 1.8% higher efficiency and 20dB lower conduction noise than those of the conventional three-phase hard-switching PWM AC/DC-DC/AC converter system. It is proved that actual efficiency of the proposed three-phase AC/DC-DC/AC converter system operating under a condition of soft switching is 88.7% under 10kw output power.

• 전기전자학회논문지
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• 제25권3호
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• pp.517-527
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• 2021

본 논문에서는 단일칩 마이컴을 이용한 위상변위 방식 직류-직류 전력변환기를 제안한다. 제안한 전력변환기의 1차측은 위상변위 방식에 의하여 단극성 펄스폭변조(unipolar PWM)로 동작하는 풀브리지 전력구조이며, 2차측은 4개의 다이오드로 구성된 풀브리지 전파정류기이다. 제안한 전력변환기의 제어는 단일칩 마이컴에 의해 수행되고, 그 MOSFET 스위치들은 부트스트랩 회로에 의해 구동된다. 그래서 전력변환기의 전체 시스템은 간단하다. 제안한 전력변환기는 공진회로와 저지커패시터를 이용하여 고효율을 달성한다. 본 논문에서는 먼저, 제안한 전력변환기의 전력회로의 동작을 각 동작모드를 따라 설명한다. 그리고 제안한 전력변환기의 전력회로 설계방식을 보이고 제안한 전력변환기를 동작시키는 마이컴 상의 소프트웨어 제어 알고리즘과 피드백 및 스위치 구동 회로에 관하여 간략히 설명한다. 그 후, 본 논문에서 제시한 설계와 구현방식에 의하여 설계하고 제작된 시제품 전력변환기의 실험결과를 통하여 제안한 전력변환기의 동작 특성을 입증한다. 실험결과에서 약 92% 정도의 최고 효율을 얻었다.