• Journal of electromagnetic engineering and science
• /
• v.12 no.4
• /
• pp.240-246
• /
• 2012

This paper presents a novel modeling technique for traces that cross a defected ground structure. A simple and accurate equivalent circuit model provides clear insight into the coupling mechanism between a microstrip line and a slot or split. The circuit models consist of a transformer as the coupling mechanism and LC resonators as the ground with a slot or split structure. Resistors, capacitors, and inductors are added to the model to increase accuracy and equivalence at high frequency. Simulated and measured S-parameters are presented for defected ground structures. The accuracy and validity of the proposed equivalent circuit model is verified by evaluation of the S-parameter characteristics of the defected ground structures and comparison with measured results.

• Proceedings of the KIPE Conference
• /
• 2016.07a
• /
• pp.441-442
• /
• 2016

본 연구에서는 상용차의 무시동시 에어컨용 공진형 컨버터의 고주파 변압기 설계에 대하여 다룬다. 고주파 변압기에 적합한 코어 선정과 Area Product Ap에 의한 코어 형상 파라미터 선정법을 도출하고, 표피효과를 줄이기 위한 권선의 재질과 안정한 직류출력 전압을 얻기 위한 변압기 권선비를 제시한다. 설계된 변압기를 MAXWELL로 모델링하고 누설자속 분포를 확인한다. 공진형 컨버터에 설계된 변압기를 적용한 결과, 변압기 인덕턴스와 출력배압회로의 커패시터간의 공진이 잘 이루어짐을 확인할 수 있었다.

• Proceedings of the KIPE Conference
• /
• 2013.11a
• /
• pp.145-146
• /
• 2013

본 논문은 슈퍼커패시터용 양방향 DC-DC 컨버터의 고주파 변압기 권선비를 고려한 설계에 대해 다루었다. 양방향 DC-DC 컨버터는 슈퍼커패시터의 충전시 스위칭 손실을 줄이기 위해 듀티(Duty)를 제어하여 Buck 모드로 동작하고, 방전시 부하변동에 빠르게 대처하기 위해 Phase-shift 모드로 동작한다. 충전시와 방전시 각각의 동작에서 스위치손실과 변압기의 손실을 분석하여 손실을 최소로하는 변압기 권선비를 선정하고자 한다.

• Proceedings of the KIPE Conference
• /
• 2003.07a
• /
• pp.36-39
• /
• 2003

The push pull forward converter is a very suitable circuit for low output voltage, high output current applications with a wide input voltage range. All the magnetic components (output inductor, transformer, input filter) can be integrated into a single core. The integrated magnetics can reduce the number of the magnetic components. Developed the push pull forward converter rating are of 36 $\~$72V input and 3.3V/30A output. In this converter, the efficiency was measured by $76.4\%$ at full load and 82.95$\%$ at full load. The maximum efficiency is up to 83.$\%$ at 200kHz switching frequency, l1A output.

• Proceedings of the KIPE Conference
• /
• 2003.07a
• /
• pp.102-105
• /
• 2003

The leakage inductance of the High frequency Transformer(HFT) in the flyback topology can be used an inductor of the Low Pass Filter(LPF) to reduce ripple and ripple noise in the output voltage. But, the values of leakage inductance and magnetizing inductance in the HFT are within $\pm20[{\%}]$). And the operating temperature of the HFT increased by the leakage inductance. Therefore, the leakage inductance of the HFT in the flyback topology has minimum and the LPF has non-polarity ceramic capacitor in the output stage. In this paper, the LPF in the flyback topoBogy takes PCB capacitor using double layer of PCB without non-polarity ceramic capacitor. Its experimental results show the reduced ripple noise and the reduced ripple in the output stage.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.670-673
• /
• 2000

This paper describes a new inverter active inverter between a photovoltaic(PV) array and single-phase utility that avoid the bulky input(60Hz) transformer on the AC side. The interface employs a pwm boost converter on the DC side followed by a pwm boost converter on the DC side followed by a pwm current-forced single-phase rectifier for injecting the power from the PV array into the mains. The current waveform at the AC side remains sinusoidal and exactly in phase at all time. The circuit also has the advantage of requiring fewer switching device than high-frequency link system. This paper describes modeling of PV array and new system topology. Simulation results on the performance of the connection are also presented.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.2083-2084
• /
• 2011

본 논문에서는 유입식변압기에 대한 부분방전진단방법에 있어 초음파센서 및 HFCT(High Frequency Current Transducer)센서의 동시측정방법 이용하여 유입식변압기 내부에서 발생한 부분방전신호의 위치추적 및 현장잡음에서의 유효한 부분방전 위치추적을 위한 하이브리드 센서적용방법을 제안하고 국내외 부분방전진단시험을 통하여 제안한 진단방법을 이용한 부분방전위치추적에 대한 고장진단사례를 소개하고자 한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.6
• /
• pp.538-543
• /
• 2008

Nanostructured materials are attracting increased interest and application. Exciting perspectives may be offered by electrical insulation. Epoxy/Organoclay nanocomposites may find new and upgraded applications in the electrical industry, replacing conventional insulation to provide improved performances in electric power apparatus, e.g, high voltage motor/generator stator winding insulation, dry mold transformer, etc. In the paper work, the electrical and thermal properties of epoxy/organoclay nanocomposites materials were studied. The electrical insulation characteristics were analyzed through the permittivity characteristics. by analyzing the permittivity spectra, it was found that dielectric constant becomes smaller with increase frequency and becomes larger with increase temperature. This indicates restriction of molecular motion and strong bonds at the epoxy/organoclay nanocomposites. The morphology of nanocomposites obtained was examined using TEM and X-ray diffraction. It has been shown that the presence of polar groups leads to an increased gallery distance and partial exfoliation. Nevertheless, full exfoliation of clay platelets has not been achieved.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.6
• /
• pp.1064-1069
• /
• 2010

Active clamp forward converter provides zero voltage switching, low voltage stress and wide input voltage range. The design technique leads to getting a higher efficiency under high switching frequency and optimal operating range. It is designed for notebook computer adapter with free input voltage and 19.5V/120W output ratings. The efficiency is measured to more than 90%. One of the most important circuit parts is the filter inductor besides the transformer in active clamp forward converter. In this paper, the process of inductor design is listed optimally.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.2031_2032
• /
• 2009

가스절연개폐장치(GIS)에 적용하고 있는 극초단파(Ultra High Frequency, UHF) 전자기파 부분방전 측정기술을 전력용 변압기 분야에 적용하는데 외부잡음 유입특성을 고려하여야 한다. 부싱을 통하여 부분방전 신호 이외의 외부잡음의 유입가능성이 크다. 따라서 본 논문에서는 현장에 설치 운전중인 154kV 변압기에 UHF 센서를 설치하여 부싱을 통해 유입되는 외부잡음을 0~2GHz 의 주파수영역에서 측정 하였다.