• Journal of international Conference on Electrical Machines and Systems
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• 제1권4호
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• pp.483-491
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• 2012

It is expected that, in the future, DC power service will be widely used for photovoltaic home power generation systems, since DC consuming devices are ever increasing. Instead of using multiple converters to convert DC to AC and then AC to DC, the power service could solely be based on DC. This would eliminate the need for converters, reducing the cost, complexity, and possibly increasing the efficiency. However, configuration of direct DC power service with mechanical contacts can cause spark voltage or an electric shock when the switch is turned on and off. To solve these problems, in this paper, a contactless power supply for a DC power service that can transfer electric power produced by photovoltaics to the home electric system using magnetic coupling instead of mechanical contacts has been proposed. The proposed system consists of a ZVS boost converter, a half-bridge LLC resonant converter, and a contactless transformer. This proposed contactless system eliminates the use of DC switches. To reduce the stress and loss of the boost converter switching devices, a lossless snubber with coupled inductor is applied. In this paper, a switching frequency control technique using the contactless voltage sensing circuit is also proposed and implemented for the output voltage control instead of using additional power regulators. Finally, a prototype consisted of 150W boost converter has been designed and built to demonstrate the feasibility of the proposed contactless photovoltaic DC power service. Experimental results show that 74~83% overall system efficiency is obtained for the 10W~80W load.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.376-379
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• 2005

High efficiency and low cost sustain driver for plasma display panel (PDP) with current fed is proposed. Main concept of the proposed circuit is using the current source to charge and discharge panel. As a result, all power switches can achieve the zero voltage switching (ZVS) and every auxiliary switch can also do the zero current switching (ZCS). Moreover, since the inductor current can compensate the discharge current, the current stress of all power switches can be reduced considerably. Furthermore, it has features as a simpler structure, less mass, less cost, and lower electromagnetic interference than prior circuit.

• 한국안전학회지
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• 제26권1호
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• pp.8-14
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• 2011

Noise and vibration are likely to disturb the sensory system of human body leading to psychological stress and thereby property damage. In this research, a cut out switch(COS) with a built-in acoustic absorber along with a COS fuse broken was developed to reduce percussion noise. This new system is based on a design approach that combines existing absorber systems: expansion type, resonator type, and acoustic absorber type silencer The noise performance of the new system was simulated using the $SYSNOISE^{TM}$ software under optimized parameters: the diameter of perforated plate 2 mm, the plate thickness 3 mm, the width of expansion room 25 mm, the impinging vortex room 14 mm, and the noise absorbtion room 10 mm. The results showed that it reduced noise by approximately 41.1 dB compared to the current systems available in the market. Furthermore, it showed reduced noise by approximately 12 dB more than a product with an acoustic absorber of the Fault Tamer(USA).

• 전력전자학회논문지
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• 제22권6호
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• pp.551-554
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• 2017

This paper proposes a three-level LLC resonant converter using integrated magnetics (IM). Given that the switch voltage stress of the proposed converter is guaranteed to be half of the input voltage, the switching losses can be greatly reduced, thereby benefitting the high-frequency operation. To reduce the volume of reactive components such as transformers, high-frequency driving and planar core are applied. However, two resonant inductors and one transformer are required because of the three-level structure and the limited leakage inductance of the planar transformer for the resonant operation. Therefore, the effect of volume reduction is not very large. In order to solve these drawbacks, this paper proposes a new IM that integrates all magnetic elements used in the proposed three-level resonant converter by using the magnetizing inductor as a resonant inductor. The experimental results are presented by conducting a theoretical analysis of a prototype with 350 W to 800 kHz.

• 조명전기설비학회논문지
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• 제15권1호
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• pp.51-58
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• 2001

현재의 DC-DC 컨버터는 스위칭 주파수를 높임에 따라 전체 손실이 현저히 증가하고 있다. 스위칭 손실을 줄이기 위해 사용한 예전의 soft 스위칭기술은 심지어 전압/전류 부담(stress)을 가중시켰다. 이에 대한 대책으로 soft 스위칭을 위한 공진회로를 주전력선에 병렬로 연결하고 보조 스위치를 이용하여 주 스위치의 turn-on 직전에만 공진회로를 동작시키는 유사공진 컨버터(QRC)기술이 발전되었다. 그러나 이 기술을 사용하는 컨버터에서도 손실은 여전히 발생하며 효율에 대한 전체적인 손실량은 알 수 있지만 각 소자에 대한 손실량은 알아볼 수 없었다. 따라서 본 논문에서는 컨버터의 주전력단에 사용되는 반도체 소자들의 선형화 된 손실등가 모델을 만들고 스위칭 시의 전압/전류 파형을 바탕으로 선형 특성을 고려하여 전체 손실에 대한 각 소자의 손실과 스위칭 손실을 분석하였다.

• 전력전자학회논문지
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• 제14권1호
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• pp.46-53
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• 2009

본 논문은 다중출력 전원 시스템을 위한 새로운 구조의 영전류 스위칭(ZCS, Zero Current Switching) LLC 공진형 Post-regulator를 제안한다. 기존의 LLC 공진형 컨버터는 정밀한 다중 출력을 얻기 위해 추가의 비 절연형 DC/DC 컨버터가 요구되었고, 이는 전력 변환 효율 감소 및 제조 원가 상승의 단점을 갖고 있다. 제안된 Post-regulator는 각 정류 다이오드 및 전력 스위치의 내압 및 전류 스트레스가 작고, 부피가 큰 고가의 비 절연형 DC/DC 컨버터의 추가 대신 1 개의 보조 스위치만으로 구현되므로 구조가 간단하고, 저가격화에 유리하다. 또한, 제안된 Post-regulator의 모든 전력 스위치는 영전류 스위칭이 가능하므로 EMI 특성이 우수하며 스위칭 손실을 최소화 할 수 있다. 최종적으로 본 논문에서 제안된 전원 시스템의 동작 원리 및 타당성을 검증하기 위하여, 영전류 스위칭 LLC 공진형 Post-regulator의 실험 결과를 제시한다.

• 한국포장학회지
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• 제28권2호
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• pp.143-149
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• 2022

PCS needs to freely switch AC and DC to connect the battery, external AC loads and renewable energy in both directions for energy efficiency. Whenever converting happens, power loss inevitably occurs. Minimization of the power loss to save electricity and convert it for usage is a very critical function in PCS. PCS plays an important role in the ESS(Energy Storage System) but the importance of stabilizing semiconductors on PCB(Printed Circuit Board) should be empathized with a risk of failure such as a fire explosion. In this study, the temperature variation inside PCS was reviewed by cooling fan on top of PCS, and the vibration characteristics of PCS were analyzed during truck transportation for reliability of the product. In most cases, a cooling fan is mounted to control the inner temperature at the upper part of the PCS and components generating the heat placed on the internal aluminum cooling plate to apply the primary cooling and the secondary cooling system with inlet fans for the external air. Results of CFD showed slightly lack of circulating capacity but simulated temperatures were durable for components. The resonance points of PCS were various due to the complexity of components. Although they were less than 40 Hz which mostly occurs breakage, it was analyzed that the vibration displacement in the resonance frequency band was very insufficient. As a result of random-vibration simulation, the lower part was analyzed as the stress-concentrated point but no breakage was shown. The steel sheet could be stable for now, but for long-term domestic transportation, structural coupling may occur due to accumulation of fatigue strength. After the test completed, output voltage of the product had lost so that extra packaging such as bubble wrap should be considered.