• 한국멀티미디어학회논문지
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• 제11권10호
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• pp.1392-1402
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• 2008

홈 게이트웨이는 유비쿼터스 홈 서비스를 지속적으로 제공하기 위해 24시간 가동되므로 연간 소모하는 전력의 규모가 크다. 네트워크의 유휴 시간에 최소 전력을 사용하는 전력 절감 모드를 적용하면 이러한 전력 소모를 줄일 수 있다. 본 논문의 전력 절감 모드 결정 알고리즘은 유휴 시간이 시작되면 유휴 시간의 누적된 정보를 토대로 현재의 유휴 시간의 길이를 예측하고, 그 결과에 따라 전력 절감 모드로 전환한다. 전력 절감 모드에서 간단한 제어용 프로토콜 데이터는 활성 모드로의 전환 없이 프록시로 처리한다. 그리고 사용자 트래픽이 존재할 경우에만 활성 모드로 전환한다. 이러한 알고리즘을 검증하기 위해서는 흠 네트워크에서 트래픽 데이터를 수집하여, 시뮬레이션을 수행하였다. 그 결과 기존 방식에 비해 최소 14%에서 최대 49%의 전력 절감 효과를 보였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.838-841
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• 2012

본 논문에서는 온도변화에 따른 회로 손상이나 성능 저하를 피하기 위해서 회로 안에 내장할 수 있는 온도 센서 회로를 설계하였다. 일반적인 PTAT회로를 사용하여 온도감지를 하고, 스위치를 내장시켜 회로 동작이 불가능할 정도로 IC 내부 온도가 높을 때는 절전모드로 동작하게 하였다. 또한, 전류미러 및 캐스코드회로를 사용함으로서 전류 정합특성을 향상시켰다. 시뮬레이션 결과 $75^{\circ}C$일 경우 약 1V, $130^{\circ}C$일 경우 1.75V를 출력전압을 발생하였으며, 절전모드의 경우 0V~7uV까지 즉 거의 0V에 가까운 출력전압을 발생함을 확인 할 수 있었다.

• 전력전자학회논문지
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• 제2권3호
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• pp.37-43
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• 1997

2상 하이브리드 스텝모터를 미세스텝으로 제어하면 저속에서도 부드럽게 회전하고, 스텝 분해능을 높일 수 있으며, 공진으로 인한 바람직하지 못한 현상들을 제거할 수 있다. 본 논문에서는 고성능 미세스텝 구동회로를 개발하였다. 본 논문에서 개발한 미세스텝 구동회로는 2상 하이브리드 스텝모터의 1회전스텝(1.8도)을 128 미세스텝으로 구동할 수 있는 위치 분해능을 가지며 스텝모터를 장시간 구동할 때 발생되는 열로 인한 문제점을 줄이기 위한 전류 절약 동작모드를 지원한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.203-205
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• 2006

This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit incorporating boost-half-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switching mode and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft switching (ZVS) operation ranges and the power dissipation as compared with those of the previously developed high-frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation (PWM) and pulse density modulation (PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.387-390
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• 2006

This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit Incorporating boost-half-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switching mode and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft switching (ZVS) operation ranges and the power dissipation as compared with those of the previously developed high-frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation (PWM) and pulse density modulation (PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

• Journal of Power Electronics
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• 제10권1호
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• pp.27-33
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• 2010

This paper presents a bidirectional DC-DC converter suitable for low-voltage super capacitor-based electric energy storage systems. The DC-DC converter presented here consists of a full-bridge circuit and a current-fed push-pull circuit with a high frequency (HF) transformer-link. In order to reduce the device-conduction losses due to the large current of the super capacitor as well as unnecessary ringing, synchronous rectification is employed in the super capacitor-charging mode. A wide range of voltage regulation between the battery and the super capacitor can be realized by employing a Phase-Shifting (PS) Pulse Width Modulation (PWM) scheme in the full-bridge circuit for the super capacitor charging mode as well as the overlapping PWM scheme of the gate signals to the active power devices in the push-pull circuit for the super capacitor discharging mode. Essential performance of the bidirectional DC-DC converter is demonstrated with simulation and experiment results, and the practical effectiveness of the DC-DC converter is discussed.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.137-143
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• 2013

This paper presents development of variable speed generation (VSG) system with energy saving function. The rubber tyred gantry crane (RTGC) requires the power from diesel-engine. Significant fuel savings by reducing the engine speed can be achieved, because all of operation modes except hoisting are required lower power than rated value of engine. When low speed operation output voltage of generator is decrease until acceptable range of motor driver inverters and auxiliary load supplier. According to power demand engine speed is varying from 20 to 60Hz, and voltage is varying between 210Vac and 480Vac. When idle mode or low power operation dc/dc converter operates by constant output voltage control and inverters dc site voltage is compensated by it. This paper proposed 3-phase interleaved boost converter which has the same structure as the commercially available 3-phase inverter and current sharing capability. 400kW interleaved converter is designed and a performance of converter is evaluated through several experiments with a RTGC system. Energy saving VSG system can cut down fuel consumption by 36% and 21.3% at idle and unidirectional load operations.

• KIEE International Transactions on Power Engineering
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• 제3A권4호
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• pp.222-230
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• 2003

This paper presents reference designs for vapor-cooled HTS/Copper leads rated at 25 kA and 40 kA and that satisfy a protection criterion. Each HTS section is cooled by the effluent helium vapor boiling from a 4.2-K bath. Each HTS section is based on a design concept in which a short portion of its warm end (77.3 K) operates in the current-sharing mode; such operation results in a considerable saving for HTS materials required in the HTS section. Two designs of "fully superconducting" vapor-cooled HTS sections, one rated at 25 kA and the other at 40 kA are also presented as comparison bases for the new HTS sections. Each warm end of HTS sections is coupled to an optimal vapor-cooled copper lead rated at the same current as that for the HTS section. The extra coolant required at 77.3 K at the coupling station, an optimal length of the copper section will be shorter than that optimized for helium-vapor cooling between 4.2 K and room temperature.mperature.

• 조명전기설비학회논문지
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• 제23권7호
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• pp.75-80
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• 2009

In this study, a Web server was constructed using LabVIEW's DataSocket, which makes possible acquisition, analysis, and saving in real time. The output value of the optical current sensor at the web server PC was measured and the output value was displayed using the Web browser of the client PC. DataSocket by LabVIEW makes the construction of a Web server easier than other languages and is compatible with other application programs. An optical current sensor was composed using a 1310 [nm] laser diode, and 9/125 [${\mu}m$] standard single mode optical fiber and was created to be a close type sensor. Data measurement using Web servers has the advantage of monitoring electric power systems at a great distance and can fuse IT technology and electric power systems. Also, this measurement uses inexpensive mounting and programming when compared to existing measurement equipment allowing the construction of a measurement system in any situation or surrounding.

• Journal of Power Electronics
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• 제4권4호
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• pp.237-245
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• 2004

In this paper, a two-switch high frequency flyback transformer linked zero voltage soft switching PWM DC-DC power converter implemented for distributed DC- feeding power conditioning supplies is proposed and discussed. This switch mode power converter circuit is mainly based on two main active power semiconductor switches and a main flyback high frequency transformer linked DC-DC converter in which, two passive lossless quasi-resonant snubbers with pulse current regeneration loops for energy recovery to the DC supply voltages composed of a three winding auxiliary high frequency pulse transformer, auxiliary capacitors and auxiliary diodes for inductive energy recovery discharge blocking due to snubber capacitors are introduced to achieve zero voltage soft switching from light to full load conditions. It is clarified that the passive resonant snubber-assisted soft switching PWM DC-DC power converter has some advantages such as simple circuit configuration, low cost, simple control scheme, high efficiency and lowered noises due to the soft switching commutation. Its operating principle is also described using each mode equivalent circuit. To determine the optimum resonant snubber circuit parameters, some practical design considerations are discussed and evaluated in this paper. Moreover, through experimentation the practical effectiveness of the proposed soft switching PWM DC-DC power converter using IGBTs is evaluated and compared with a hard switching PWM DC-DC power converter.