• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.525-528
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• 2002

A Novel Zero Current Switching(ZCS) Pulse Width Modulation(PWM) boost converter for reducing two rectifiers reverse recovery related losses Is proposed. The switches of the proposed converter are operating to work alternatively turn-on and turn-off with soft switching(ZVS, ZCS) condition. The reverse recovery related switching losses and EMI problems of the proposed converter eliminates the reverse recovery current of the freewheeling diode(D, Dl) by adding the resonant inductor Lr, in series with the switch S2. The voltage and current stresses of the components are similar to those in its conventional hard switching counterpats. As mentioned above, the characteristics are verified through experimental results.

• Journal of Semiconductor Engineering
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• 제3권1호
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• pp.154-160
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• 2022

In this paper, we design a DC-DC boost converter with RF noise immunity to supply a stable positive output voltage for OLED displays. For RF noise immunity, an input voltage variation reduction circuit (IVVRC) is adopted to ensure display quality by reducing the undershoot and overshoot of output voltage. The boost converter for a positive voltage Vpos operates in the SPWM-PWM dual mode and has a dead-time controller using a dead-time detector, resulting in increased power efficiency. A chip was fabricated using a 0.18 um BCDMOS process. Measurement results show that power efficiency is 30% ~ 76% for load current range from 1 mA to 100 mA. The boost converter with the IVVRC has an overshoot of 6 mV and undershoot of 4 mV compared to a boost converter without that circuit with 18 mV and 20 mV, respectively.

• 전력전자학회논문지
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• 제21권5호
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• pp.434-441
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• 2016

This paper deals with transformer turns ratio design with the consideration of loss minimization in isolated bidirectional DC-DC converter. Generally, the rms value of current, magnitude of current at switching instance, and duty ratio of a converter vary according to the turns ratio of an isolation transformer in the converter under the same voltages and output power level. Therefore, the transformer turns ratio has an effect on the total loss in a converter. The switching and conduction losses of IGBTs and MOSFETs consisting of dual-active bridge converter are analyzed, and iron and copper losses in an isolation transformer and inductor are calculated. Total losses are calculated and measured in cases of four different transformer turns ratios through simulation and experiment with 3-kW converter, and an optimum turns ratio that provides minimum losses is found. The usefulness of the proposed transformer turns ratio design approach is verified through simulation and experimental results.

• Journal of Power Electronics
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• 제15권2호
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• pp.309-318
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• 2015

This study proposes a dual-output single-stage bridgeless single-ended primary-inductor converter (DOSSBS) that can completely remove the front-end full-bridge alternating current-direct current rectifier to accomplish power factor correction for universal line input. Without the need for bridge diodes, the proposed converter has the advantages of low component count and simple structure, and can thus significantly reduce power loss. DOSSBS has two uncommon output ports to provide different voltage levels to loads, instead of using two separate power factor correctors or multi-stage configurations in a single stage. Therefore, this proposed converter is cost-effective and compact. A magnetically coupled inductor is introduced in DOSSBS to replace two separate inductors to decrease volume and cost. Energy stored in the leakage inductance of the coupled inductor can be completely recycled. In each line cycle, the two active switches in DOSSBS are operated in either high-frequency pulse-width modulation pattern or low-frequency rectifying mode for switching loss reduction. A prototype for dealing with an $85-265V_{rms}$ universal line is designed, analyzed, and built. Practical measurements demonstrate the feasibility and functionality of the proposed converter.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권4호
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• pp.739-749
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• 2015

A new conceptual dual-buoy Wave Energy Converter (WEC) for the enhancement of energy extraction efficiency is suggested. Based on actual wave data, the design process for the suggested WEC is conducted in such a way as to ensure that it is suitable in real sea. Actual wave data measured in Korea's East Sea (position: $36.404N^{\circ}$ and $129.274E^{\circ}$) from May 1, 2002 to March 29, 2005 were used as the input wave spectrum for the performance estimation of the dual-buoy WEC. The suggested WEC, a point absorber type, consists of two concentric floating circular cylinders (an inner and a hollow outer buoy). Multiple resonant frequencies in proposed WEC affect the Power Ttake-off (PTO) performance of the WEC. Based on the numerical results, several design strategies are proposed to further enhance the extraction efficiency, including intentional mismatching among the heave natural frequencies of dual buoys, the natural frequency of the internal fluid, and the peak frequency of the input wave spectrum.

• 전력전자학회논문지
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• 제7권5호
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• pp.419-426
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• 2002

전류원 하프브릿지 듀얼 컨버터(이하 '듀얼 컨버터')를 위한 새로운 능동형 무손실 스너버가 제안된다. 제안된 능동형 무손실 스너버는 주 스위치의 턴 오프 시 변압기 누설 인덕터로 인해 발생되는 스위치 양단 전압 서지를 흡수해줄 뿐만 아니라 주 스위치 및 부가된 보조스위치의 턴 온 시 영전압 스위칭까지 보장해 주기 때문에 스위칭손실을 거의 무시할 수 있으며, 고 효율 및 고속 스위칭에 매우 유리한 장점을 가져 높은 전력밀도를 가진 고성능승압형 컨버터의 구현을 가능하게 한다. 또한 영전압 스위칭을 위해 별도의 인덕터 없이 변압기의 누설 인덕터만으로 그 구현이 가능하며 보조 스위치의 구동신호가 주 스위치와 교대로(complementary) 온 오프 되므로 별도의 PWM IC가 필요 없는 간단한 구조를 가지며, 제작 시 단가 절감 효과를 얻을 수 있다. 본 논문에서는 기존에 제안된 바 있는 듀얼 컨버터에 제안된 능동형 무손실 스너버를 적용하여 그 동작 원리, 영전압스위칭 조건, 그리고 설계방법 등에 대해 살펴보고 최종적으로 제시된 이론적인 분석결과 및 동작의 유효성 검증을 위해 24V/DC 입력에 200V/DC 출력을 갖는 200W급 축소모델을 제작하여 100kHz로 구동한 실험 결과를 제시한다.

• 한국정보통신학회논문지
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• 제23권7호
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• pp.816-821
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• 2019

듀얼에지 T 플립플롭을 사용하여 카운터 타입의 시간-디지털 변환기를 설계하였다. 시간-디지털 변환기는 공급 전압 1.5volts에서 $0.18{\mu}mCMOS$ 공정으로 설계하였다. 일반적인 시간-디지털 변환기에서 클록의 주기가 T일 때, 입력신호와 클록의 비동기로 인하여 클록의 주기에 해당하는 변환 에러가 발생한다. 그러나 본 논문에서 제안한 시간-디지털 변환기의 클록은 입력신호인 시작신호와 동기화되어 생성된다. 그 결과 시작신호와 클록의 비동기로 인해 발생할 수 있는 변환 에러는 발생하지 않는다. 그리고 카운터를 구성하는 플립플롭은 분해능 향상을 위해 클록의 상승에지와 하강에지에서 동작하는 듀얼에지 플립플롭으로 구성하였다.

• 한국철도학회논문집
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• 제19권6호
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• pp.727-735
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• 2016

철도차량용 구동 시스템의 주 변압기를 지능형 변압기로 대체하는 것은 철도차량의 효율을 높이기 위한 효과적인 방법이다. 지능형 변압기는 고전압 입력단을 저전압 직류단으로 변환하는 정류단 모듈과, 변환된 복수의 저전압 직류단 전압을 직/병렬로 연결하여 저전압 직류 출력 전압을 제어하는 Dual Active Bridge (DAB) 컨버터 모듈로 구성된다. DAB 컨버터는 고주파 변압기를 사이에 두고 양 측 Full-Bridge 컨버터의 전압 합성 방법에 따라 전력이 양방향으로 전달될 수 있다. 이 때, 양 측 Full-Bridge 컨버터의 전압 합성 방법에 따라 고주파 변압기로 흐르는 전류의 형태가 달라지게 되며, 이는 효율에 직접적인 영향을 미치게 된다. 본 논문은 중/저 전력 조건에서 DAB 컨버터의 효율을 개선하기 위한 새로운 modulation 방법을 제안한다. 제안하는 modulation 방법은 DAB 컨버터 내에 발생할 수 있는 무효 전력을 0으로 제어하도록 하며, 출력단 컨버터를 다이오드 정류기와 유사한 동작을 하도록 함으로써, 스위칭 손실을 최소화하도록 하였다. 제안된 modulation 방법을 통한 손실 저감은 900Vdc의 직류단 전압을 갖는 DAB 컨버터에 대한 시뮬레이션 결과를 통해 검증하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.708-712
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• 2001

A new phase-shifted parallel-input/series-output (PI SO) dual inductor-fed push-pull converter for high-power step­up applications is proposed. This converter is operated at a constant duty cycle and employs an auxiliary circuit to control the output voltage with a phase-shift between the two modules. It features a voltage conversion characteristic which is linear to changes in the control input, and high step-up ratio with a greatly reduced switch turn-off stress resulting in a significant increase in the converter efficiency. It also shows a low ripple content and low root-mean-square (RMS) current in the output capacitor. The operational principle is analyzed and a comparative analysis with the conventional pulse-width-modulated (PWM) PISO dual inductor-fed push-pull converter is presented. A 50kHz, 800W, 350Vdc prototype with an input of 20-32Vdc has also been constructed to validate the proposed converter. The proposed converter compares favorably with the conventional counterpart and is considered well suited to high-power step-up applications.

• Journal of Power Electronics
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• 제1권2호
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• pp.78-87
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• 2001

A new high-power step-up based on the two-module parallel-input (PISO) modular dual inductor-fed push-pull converter is proposed. The proposed converter is operated at a constant duty cycle and employs and auxiliary circuit to control the output voltage with a phase-shift between two modules. It shows a high efficiency due to the greatly reduced switch turn-off stress. It also shows a high and linear voltage conversion ratio, low current stress in the output capacitor, and fast control-to-output dynamics. The operation principles and the mathematical models of the proposed converter are presented. Features of the proposed converter are discussed in comparison with the two-module PISO modular dual inductor-fed push-pull converter. Also, experimental results from a 50kHz, 800W, 350 Vdc prototype with an input voltage range of 20-32 Vdc are provided to confirm the validity of the proposed converter. The new converter compares favorably with the conventional counterpart, and is considered well siuted to high-power step-up applications.