• 한국초전도ㆍ저온공학회논문지
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• 제11권1호
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• pp.35-38
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• 2009

The high temperature superconducting(HTS) power cable, as a key component of the next generation power transmission system, operates cost-effectively because of much less transmission loss. Currently, a world-wide research has been undertaken actively. In this research, we designed insulation thickness and investigated thickness effect of laminated polypropylene paper(LPP) which is insulation material of HTS cable in case of AC and impulse breakdown.

• 한국전기전자재료학회논문지
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• 제28권4호
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• pp.222-228
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• 2015

Power MOSFETs (metal oxide semiconductor field effect transistor) operate as energy control semiconductor switches. In order to reduce energy loss of the device, it is essential to increase its conductance. However, a trade-off relationship between the breakdown voltage and conductance of the device have been the critical difficulty to improve. In this paper, theoretical analysis of electrical benefits on single floating island power MOSFET is proposed. By the method, the optimization point has set defining the doping limit under single floating island structure. The numerical multiple 2.22 was obtained which indicates the doping limit of the original device, improving its ON state voltage drop by 45%.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권3호
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• pp.263-267
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• 2014

Super junction trench gate power MOSFETs have been receiving attention in terms of the trade-off between breakdown voltage and on-resistance. The vertical structure of super junction trench gate power MOSFETs allows the on-resistance to be reduced compared with conventional Trench Gate Power MOSFETs. The heat release of devices is also decreased with the reduction of on-resistance. In this paper, Lattice Temperature of two devices, Trench Gate Power MOSFET and Super junction trench gate power MOSFET, are compared in several temperature circumstance with the same Breakdown Voltage and Cell-pitch. The devices were designed by 100V Breakdown voltage and measured from 250K Lattice Temperature. We have tried to investigate how much temperature rise in the same condition. According as temperature gap between top of devices and bottom of devices, Super junction trench gate power MOSFET has a tendency to generate lower heat release than Trench Gate Power MOSFET. This means that Super junction trench gate power MOSFET is superior for wide-temperature range operation. When trench etching process is applied for making P-pillar region, trench angle factor is also important component. Depending on trench angle, characteristics of Super junction device are changed. In this paper, we focus temperature characteristic as changing trench angle factor. Consequently, Trench angle factor don't have a great effect on temperature change.

• Journal of Electrical Engineering and Technology
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• 제7권5호
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• pp.772-777
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• 2012

Accidents caused by water absorption in water-cooled generator stator windings often occur all over the world. The absorption into the insulator of the coolant, which is used to cool down the heat generated by stator windings during operation, leads to the deterioration of dielectric strength, and insulation breakdown. An insulation breakdown may cause not only an enormous economic loss but also a very serious grid accident that would compromise stable supply of electric power. More than 50 % of domestic generators have been in operation for more than 15 years, and water absorption tests performed on 50 water-cooled generator stator windings during a five-year planned preventive maintenance period beginning in 2006 identified water absorption problems in 10 of them, all of which required repair. Because the existing water absorption test detects this problem by utilizing stochastic methods after measuring the capacitances at the final positions of insulation breakdown, its accuracy is limited. This study demonstrates that water absorption can be more accurately diagnosed by utilizing method along with a more precise one.

• 한국정보통신학회논문지
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• 제8권8호
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• pp.1719-1724
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• 2004

본 논문에서는 차세대 RF 전력 소자로 기대하고 있는 LDMOST의 BV(Breakdown; 항복전압) 특성을 향상시키는 새로운 구조를 제안하였다. 제안한 구조는 외부 전계 링이라 하며 드리프트 영역 둘레에 3차원적인 구조로 형성된다. 외부 전계 링은 드리프트 영역에서 전계를 완화시키는 역할을 함으로써 BV 특성을 향상시키는 효과를 얻을 수 있다. 3차원 TCAD 시뮬레이션 결과, 외부 전계 링의 접합깊이와 도핑 농도의 증가에 따라 LDMOST의 BV가 증가함을 확인할 수 있었다. 따라서 기존의 p+ sinker 공정을 사용하여 외부 전계 링 구조를 추가한다면 LDMOST의 BV 특성을 크게 향상 시킬 수 있다.

• 한국전기전자재료학회논문지
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• 제25권4호
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• pp.309-314
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• 2012

To assess the condition of stator insulation, nondestructive and overpotential tests were performed on four high voltage motors. The stator windings under these tests have nominal ratings of 6.6 kV. After completing nondestructive tests, the AC overvoltage applied to the stator windings was gradually increasing until insulation failure in order to obtain the breakdown voltage. No. 1, No. 2, No. 3 and No. 4 of 6.6 kV motors failed near rated voltage of 18.4 kV, 19.8 kV, 19.7 kV and 21.7 kV, respectively. The breakdown voltage of four motors was higher that expected for good quality coils(14.2 kV) in 6.6 kV motors. Almost all of failures were located in a line-end coil at the exit from the core slot. The breakdown voltages and the types of defects showed strong relation to the stator insulation tests such as in the case of AC current, dissipation factor($tan{\delta}$) and partial discharge magnitude.

• Transactions on Electrical and Electronic Materials
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• 제18권6호
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• pp.338-340
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• 2017

Breakdown of solid insulating materials in power equipment could result in undesired outages and replacements, and may be due to an increase in electric stress on the material. Therefore, it is necessary to conduct a proper diagnosis of materials before their practical use. In this work, a few inherent properties of different non-cellulosic insulating materials, such as Nomex, Teflon, laminated Nomex, glass bonded mica, epoxy resin bonded mica paper, and epoxy resin bonded fiberglass, have been evaluated by performing non-destructive dielectric diagnostic measurements, and an attempt has been made to correlate these basic parameters to evaluate the breakdown strength (BDS). An equation has been proposed using a basic theory which defines the correlation between the BDS, dielectric constant, dissipation factor, sample thickness, and volume resistivity. The results obtained from the equation are also compared with the experimental values. The suggested equation will be helpful to predict the BDS of any non-cellulosic material without experimentation in the laboratory.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1181-1187
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• 2015

Sulfur hexafluoride (SF₆) gas is used widely in electric power equipment such as Gas Insulated Switchgear (GIS), Gas Insulation transmission Line (GIL), and Gas Circuit Breaker (GCB). But applications of SF₆ should be restricted because SF6 gas is one of the greenhouse effect gases. To reduce use of SF₆ gas, a study on eco-friendly alternative insulation medium is needed. In this paper, we investigated lightning impulse (LI) breakdown of dry-air which is attracting attention as an ecofriendly alternative gas and the LI breakdown of hybrid insulation combined with dry-air and solid insulation (Room-Temperature Vulcanizing Silicone Rubber-RTV SIR) and dry-air in inhomogeneous fields according to gap distance and pressure. The experiment results showed that the LI breakdown strength of hybrid insulation system was higher than that of dry-air insulation system. It was verified that the development of technology related to eco-friendly power apparatus compact such GIS, GCB and GIL can be used as basic research data.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.693-696
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• 2004

For InGaP/GaAs HBT applications, we have developed characterized MIM capacitors with thin $1000{\AA}$ PECVD silicon nitride which were deposited with $SiH_4/NH_3$ gas mixing rate, working pressure, and RF power of PECVD at $300^{\circ}C$ and had the capacitance density of 600 pF/$mm^2$ with the breakdown electric fields of 3073 MV/cm. Three PECVD process parameters were designed to lower the refractive index and then lower the deposition rate of silicon nitride films for the high breakdown electric field. At the PECVD process condition of gas mixing rate (0.92), working pressure (1.3 Torr), RF power (53 W), the AFM Rms value of about $1000{\AA}$ silicon nitride on the bottom metal was the lowest of 0.662 nmand breakdown electric fields were the highest of about 73 MV/cm.

• 한국전기전자재료학회논문지
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• 제32권5호
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• pp.366-370
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• 2019

In this paper, a single N+ emitter trench gate-type insulated gate bipolar transistor (IGBT) device was studied using T-CAD, in order to achieve a low on-state voltage drop (Vce-sat) and high breakdown voltage, which would reduce power loss and device reliability. Using the simulation, the threshold voltage, breakdown voltage, and on-state voltage drop were studied as a function of the temperature, the length of time in the diffusion process (drive-in) after implant, and the trench gate depth. During the drive-in process, a $20^{\circ}C$ change in temperature from 1,000 to $1,160^{\circ}C$ over a 150 minute time frame resulted in a 1 to 4 V change in the threshold voltage and a 24 to 2.6 V change in the on-state voltage drop. As a result, a 0.5 um change in the trench depth of 3.5 to 7.5 um resulted in the breakdown voltage decreasing from 802 to 692 V.