• JSTS:Journal of Semiconductor Technology and Science
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• 제17권2호
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• pp.265-270
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• 2017

4H-SiC has attracted attention for high-power and high-temperature metal-oxide-semiconductor field-effect transistors (MOSFETs) for industrial and automotive applications. The gate oxide in the 4H-SiC MOS system is important for switching operations. Above $1000^{\circ}C$, thermal oxidation initiates $SiO_2$ layer formation on SiC; this is one advantage of 4H-SiC compared with other wide band-gap materials. However, if post-deposition annealing is not applied, thermally grown $SiO_2$ on 4H-SiC is limited by high oxide charges due to carbon clusters at the $SiC/SiO_2$ interface and near-interface states in $SiO_2$; this can be resolved via low-temperature deposition. In this study, low-temperature $SiO_2$ deposition on a Si substrate was optimized for $SiO_2/4H-SiC$ MOS capacitor fabrication; oxide formation proceeded without the need for post-deposition annealing. The $SiO_2/4H-SiC$ MOS capacitor samples demonstrated stable capacitance-voltage (C-V) characteristics, low voltage hysteresis, and a high breakdown field. Optimization of the treatment process is expected to further decrease the effective oxide charge density.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.250-255
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• 2006

A low cost PDP sustain power supply is proposed based on flyback topology using Boundary Conduction Mode(BCM) to control input current regulation. This method guarantees DCM condition to regulate the input current harmonics under all load conditions. An excessive voltage stress due to the link voltage increase can be suppressed by removing link capacitor and adjusting transformer turns ratios, which makes it possible to be used for universal line applications. The proposed converter is tested with a 400W(200V-2A output) prototype circuit.

• Journal of Power Electronics
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• 제7권3호
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• pp.181-190
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• 2007

This paper presents a novel circuit topology of a DC bus line series switch and parallel snubbing capacitor-assisted soft-switching PWM full-bridge inverter type DC-DC power converter with a high frequency planar transformer link, which is newly developed for high performance arc welding machines in industry. The proposed DC-DC power converter circuit is based upon a voltage source-fed H type full-bridge soft-switching PWM inverter with a high frequency transformer. This DC-DC power converter has a single power semiconductor switching device in series with an input DC low side rail and loss less snubbing capacitor in parallel with the inverter bridge legs. All the active power switches in the full-bridge arms and DC bus line can achieve ZCS turn-on and ZVS turn-off transition commutation. Consequently, the total switching power losses occurred at turn-off switching transition of these power semiconductor devices; IGBTs can be reduced even in higher switching frequency bands ranging from 20 kHz to 100 kHz. The switching frequency of this DC-DC power converter using IGBT power modules can be realized at 60 kHz. It is proved experimentally by power loss analysis that the more the switching frequency increases, the more the proposed DC-DC power converter can achieve a higher control response performance and size miniaturization. The practical and inherent effectiveness of the new DC-DC converter topology proposed here is actually confirmed for low voltage and large current DC-DC power supplies (32V, 300A) for TIG arc welding applications in industry.

• 대한전기학회논문지
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• 제43권3호
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• pp.381-387
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• 1994

In this paper, we found the improved SPICE heat transfer modeling of impulsed magnetizing fixture system and investigated temperature characteristics using the proposed model. As the detailed thermal characteristics of magnetizing fixture can be obtained, the efficient design of the impulsed magnetizing fixture which produce desired magnet will be possible using our heat transfer modeling. The knowledge of the temperature of the magnetizing fixture is very important of forecast the characteristics of the magnetizing fixture which produce desired magnet will be possible using our heat transfer modeling. The knowledge of the temperature of the magnetizing fixture is very important to forecast the characteristics of the magnetizing circuits under different conditions. The capacitor voltage was not raised above 810[V] to protect the magnetizing fixture from excessive heating. The purpose of this work is to compute the temperature increasing for different magnetizing conditions. The method uses multi-lumped model with equivalent thermal resistance and thermal capacitance. The reliable results are obtained by using iron core fixture (stator magnet of air cleaner DC motor) coupled to a low-voltage magnetizer(charging voltage : 1000[V], capacitor : 3825[$\mu$F]. The modeling and experimental results are in close aggrement.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.301-302
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• 2007

Energy harvesting from the vibration through the piezoelectric effect has been studied for powering the wireless sensor node. For the driving wireless sensor node, the generated energy is required to store the capacitor or battery. For the rapid charging, higher voltage than battery's capacity voltage and a large current are necessitated. However, the piezoelectric energy harvester is generally featured as a high voltage and low current generator. As it is known that the generated current in the piezoelectric energy harvester is related to an area of electrode of piezoelectric ceramics, we fabricated the multilayer ceramics to increase effective area for the faster charging. The energy harvesting properties and charging characteristics of multilyaer ceramics were investigated and discussed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1605-1607
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• 2000

In this paper, the design of class AB BiCMOS log-domain filter for low-voltage and low-power was proposed. This filter is consist of a log-domain integrator using folded junctions with capacitor connected to emitter and it's class AB structure. A comparison between the proposed class AB BiCMOS log-domain filter and classical class A BiCMOS log-domain filter is drawn on the basis of SNR, THD and the frequency response. This comparison shows proposed filter are more than good SNR, THD and frequency characteristics than more class A log-domain filter for low voltage and low power.

• 전기학회논문지P
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• 제65권4호
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• pp.285-291
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• 2016

A light-emitting diode (LED) has been increasingly applied to various industrial fields and general lightings because of its high efficiency, low power consumption, environment-friendly characteristic and long lifetime. To drive the LED lighting, a power converter with the constant output current is needed. Among many power converters, the flyback converter is chosen by many converter designers due to high power density, structural simplicity, and miniaturization. In this converter, an electrolytic capacitor is generally chosen for the stabilization of the DC voltage because of having the large capacitance and the low price. However, the disadvantages are the short expected life time and 120Hz ripple currents on the converter output node. In this paper, a single-stage dimmable PFC DCM flyback converter without the electrolytic capacitor is proposed to prolong the lifetime of the LED driver. For the long lifetime of the converter, the polyester film capacitor with the small capacitance is substituted for the electrolytic capacitor on the output node and an LC resonant filter is added to damp 120Hz ripple current. The proposed converter is verified through the simulation and the experimental works.

• 전력전자학회논문지
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• 제9권4호
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• pp.381-389
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• 2004

본 논문에서는 입력단 커패시터를 제거한 인버터의 제어에 아날로그 적분기를 이용한 새로운 비선형 제어 기법인 순시보상형 PWM 제어회로를 적용하고 있다. 비선형 순시보상형 PWM 제어기는 순시 입력전압의 변동에 대한 보상과 제어기준값에 대한 추종이 스위칭 한 주기 내에서 이루어지는 다이나믹하고 강인한 응답성을 가지고 있으며, 아날로그 소자를 사용하고 있어 제어회로가 간단하면, 인버터 입력 맥동전압을 보상함으로 대형의 평활용 커패시터가 필요치 않아서 소형, 저가형으로 부피가 적은 인버터를 제작 할 수 있다는 장점을 가지고 있다. 이러한 장점을 가지고 있는 순시보상형 PWM 제어 인버터를 기존의 VVVF 제어형 전동기 인버터 시스템을 대치하여 저가이고 소형의 인버터 시스템으로 제안하고 실험을 통하여 우수한 동작특성을 확인하고 있다.

• 한국전기전자재료학회논문지
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• 제27권2호
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• pp.76-80
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• 2014

Dual-gate PCRAM which unify capacitor-less DRAM and NVM using a PCM instead of a typical SONOS flash memory is proposed as 1 transistor. $VO_2$ changes its phase between insulator and metal states by temperature and field. The front-gate and back-gate control NVM and DRAM, respectively. The feasibility of URAM is investigated through simulation using c-interpreter and finite element analysis. Threshold voltage of NVM is 0.5 V that is based on measured results from previous fabricated 1TPCM with $VO_2$. Current sensing margin of DRAM is 3 ${\mu}A$. PCM does not interfere with DRAM in the memory characteristics unlike SONOS NVM. This novel unified dual-gate PCRAM reported in this work has 1 transistor, a low RESET/SET voltage, a fast write/erase time and a small cell so that it could be suitable for future production of URAM.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.281-285
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• 2001

This paper proposes a snubber circuit for flying capacitor multilevel inverter and converter. The proposed snubber circuit makes use of Undeland snubber as basic snubber unit. It has such an advantage of Undeland snubber used in the two-level inverter. Compared with conventional RLD/RCD snubber for multilevel inverter and converter, the proposed snubber keeps such good features as fewer number of components, reduction of voltage stress of main switching devices due to low overvoltage, and improved efficiency of system due to low snubber loss. In this paper. the proposed snubber is applied to three-level flying capacitor inverter and its feature is demonstrated by computer simulation and experimental result.