• 한국산업융합학회 논문집
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• 제21권6호
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• pp.265-271
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• 2018

DC-DC buck converter is a critical building block in the power management integrated circuit (PMIC) architecture for the portable devices such as cellular phone, personal digital assistance (PDA) because of its power efficiency over a wide range of conversion ratio. To ensure a safe operation, avoid unexpected damages and enhance the reliability of the converter, fully-integrated protection circuits such as over voltage protection (OVP), under voltage lock out (UVLO), startup, and thermal shutdown (TSD) blocks are designed. In this paper, these three fully-integrated protection circuit blocks are proposed for use in the DC-DC buck converter. The buck converter with proposed protection blocks is operated with a switching frequency of 1 MHz in continuous conduction mode (CCM). In order to verify the proposed scheme, the buck converter has been designed using a 180 nm CMOS technology. The UVLO circuit is designed to track the input voltage and turns on/off the buck converter when the input voltage is higher/lower than 2.6 V, respectively. The OVP circuit blocks the buck converter's operation when the input voltage is over 3.3 V, thereby preventing the destruction of the devices inside the controller IC. The TSD circuit shuts down the converter's operation when the temperature is over $85^{\circ}C$. In order to verify the proposed scheme, these protection circuits were firstly verified through the simulation in SPICE. The proposed protection circuits were then fabricated and the measured results showed a good matching with the simulation results.

• 전력전자학회논문지
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• 제20권2호
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• pp.130-136
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• 2015

This study describes the structure and operation modes of vertical stabilization (VS) converter for international thermonuclear experimental reactor (ITER) and proposes a protection method. ITER VS converter supplies voltage (${\pm}1000V$)/current (${\pm}22.5kA$) to superconducting magnets for plasma current vertical stabilization. A four-quadrant operation must be achieved without zero-current discontinuous section. The operation mode of the VS converter is separated in 12-pulse mode, 6-pulse mode and circulation current mode according to the magnitude of the load current. Protection measures, such as bypass and discharge, are proposed for abnormal conditions, such as over current, over voltage, short circuit, and voltage sag. VS converter output voltage is controlled to satisfy voltage response time within 20 msec. Bypass operation is completed within 60 msec and discharge operation is performed successfully. The feasibility of the proposed control algorithm and protection measure is verified by assembling a real controller and implementing a power system including the VS converter in RTDS for a hardware-in-loop (HIL) facility.

• 전기학회논문지
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• 제65권12호
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• pp.1979-1985
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• 2016

A protection algorithm using a voltage-controlled overcurrent element for a looped collection circuit in a wind farm is suggested in this paper. Because the proposed algorithm uses voltage relaying signals as well as current relaying signals, any fault in the looped collection circuit can be cleared by voltage-controlled overcurrent relays located at the two adjacent relaying points, the nearest place in each direction from the fault point. The algorithm can also distinguish the external faults which occur at the outside of a wind farm from the internal faults. It means that the proposed algorithm can provide the proper ability of protection coordination to the relays in the looped collection circuits of a large wind farm. The performance of the proposed algorithm is verified under various fault conditions using PSCAD/EMTDC simulations.

• 융합신호처리학회논문지
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• 제11권2호
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• pp.163-168
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• 2010

본 논문에서는 전력용 반도체 소자를 위한 과열보호시스템의 설계 및 구현에 관한 내용을 다룬다. 제안된 시스템은 전력용 반도체 소자의 온도를 검출하기 위해서 별도의 온도센서나 트랜지스터를 사용하는 기존의 방법과 달리 파워 MOSFET의 $R_{ds(on)}$ 특성만을 이용한다. 과열보호를 위한 제안된 방법은 IRF840 파워 MOSFET를 이용하여 성공적으로 시험되었다. 제안된 과열보호 알고리즘을 구현하기 위해 PIC 마이크로컨트롤러인 PIC16F877A 소자를 사용하였다. 내장된 10-bit A/D 변환기는 IRF840의 소스와 드레인 전압변화를 검출하기 위해 이용된다. 측정된 소스-드레인 간 전압으로부터 도출된 온도-저항 간의 관계식은 파워 MOSFET의 게이트 트리거 신호를 제어한다. 만약 검출된 온도 전압의 임계값이 설정된 임의의 보호온도 전압 값을 초과할 때 마이크로컨트롤러는 파워 MOSFET으로부터 트리거 신호를 제거시켜 파워 MOSFET이 과열되는 것을 방지한다. 실험결과는 제안된 시스템이 정확도 측면에서 1.5%의 오차 이내로 정확함을 보여주었다.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2001년도 춘계학술대회
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• pp.67-75
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• 2001

Circuitry to be connected to a Telecommunication Network consists of SELV CIRCUITS or TNV CIRCUITS. So International Standards, like as ITU-T Recommendation K.11, UL 1950, CSA C22.2 950 have been taken to reduce the risk that the Overvoltages from the power lines and from electrictraction lines, that may be received from the telecommunication network. Legal requirements may exist regarding permission to connect equipment having PTC components to a telecommunication network. Surge suppressors that bridge the insulation shall have a minimum d.c. sparkover voltage of 1.6 times the rated voltage or 1.6 times the upper voltage of the tared voltage range of the equipment. If left in place during electric strength testing of insulation, they shall not be damaged. In this work, The Conception ＆ Fail-Mode Analysis of PTC components for Over-Current Protection is proposed. It guarantees the protection for PL Claim about this Subject.

• 전자공학회논문지 IE
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• 제49권1호
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• pp.18-23
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• 2012

본 논문에서 소형 휴대기기용 DC-DC 변환기를 위한 전압보호회로를 설계 하였다. 제안하는 전압보호회는 저전압 보호회로(UVLO)와 고전압 보호회로(OVP) 로 구성되며, 비교기와 바이어스 회로를 사용하여 구현하였다. XFAB $1{\mu}m$ CMOS 공정을 SPICE 모의실험을 통하여 특성 확인을 하였다. 모의실험 결과, 저전압 보호회로(UVLO)는 입력 전압이 4.8 V 이상이 되면 턴-온 되며, 4.2 V 이하가 되면 턴-오프가 되어 저전압의 입력전압이 인가될 때 회로의 오작동을 막을 수 있다. 고전압 보호회로(OVP)는 기준전압 3.8V 이상의 출력전압이 발생하였을 때 회로를 차단하여 소자의 파괴를 막아 안정성과 신뢰성을 높일 수 있다. 또 가상의 DC-DC 변환기 제어회로에 연결한 결과 전압의 이상에 따른 전압보호회로의 동작여부를 확인하였다. 본 논문에서 제안하는 전압보호회로는 DC-DC 변환기의 보호회로 셀로 유용하게 사용 될 것으로 사료된다.

• 한국전기전자재료학회논문지
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• 제25권5호
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• pp.340-344
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• 2012

Protected Circuit Module protects battery from over-charge and over-discharge, also prevents accidental explosion. Therefore, power MOSFET is essential to operate as a switch within the module. To reduce power loss of MOSFET, the on state voltage drop should be lowered and the switching time should be shorted. However there is trade-off between the breakdown voltage and the on state voltage drop. The TDMOS can reduce the on state voltage drop. In this paper, effect of design parameter variation on electrical properties of TDMOS, were analyzed by computer simulation. According to the analyzed results, the optimization was performed to get 65% higher breakdown voltage and 17.4% on resistance enhancement.

• 조명전기설비학회논문지
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• 제29권2호
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• pp.91-96
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• 2015

There are provision for risk analysis in IEC standards. It is to determine the need for installation of a surge protection device (SPD) in order to protect the low-voltage electrical installations from overvoltages caused by atmospheric phenomena and the like. However, scattered many related standards, the lack of details are not easy to apply it in the field. We investigated the relevant domestic and international standards for applies to the international standards in domestic. And we proposed the flow chart for determining the need for protection of the low-voltage electrical installations from overvoltage due to atmospheric phenomena and it set the appling target facility.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.293-295
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• 2003

KEPCO's high voltage distribution power line laid under the ground near to the J-booster pumping station that supply water for living. Lightening rod equipment does not installed at the J-booster pumping station because KEPCO's over head ground wire for protection functions as a lightening rod equipment. In this study, it is concerned whether KEPCO's over head ground wire for protect the distribution power line affect to the J-booster pumping station which is installed for reduce the damage from the direct and indirect lightening. If KEPCO's protection area does not affect to the J-pumping station, it is plan to examine the construction method of lightening rod protection angle and lightening rod equipment and to suggest the optimum protection plan using the surrounding structure based on the suitability of protection area.

• 한국정보전자통신기술학회논문지
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• 제13권6호
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• pp.562-567
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• 2020

본 논문은 저장 탱크용 임시전력설비를 보호하기 위한 목적으로 특히 변압기를 감시하고 절연파괴 등과 같은 고장을 차단하고 보호하기 위한 보호계전기 정정에 관한 연구이다. 전력계통에 단락 또는 지락고장 등과 같은 이상이 발생하였을 때 이를 검출하여 고장이 발생한 기기 및 설비를 신속하게 차단하고 전력계통으로부터 분리하여 전력공급에 지장이 없도록 하여야 한다. 전력계통의 이상 상태를 빠르고 정확하게 감지할 수 있는 보호계전기의 정정이 중요하다. 또한 보호협조를 위해 고장종류와 고장의 원인을 정확히 적용한 고장전류 계산이 보호계전기 정정에 가장 중요한 요소이다. 저장 탱크용 임시전력설비 보호를 위해 적용하는 과전류계전기, 지락과전류계전기, 부족전압계전기, 지락과전압계전기 등이 보호협조가 가능하도록 보호계전기 정정 방법에 대해 연구하였다.