• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.312-315
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• 2003

Basic design of RC-GCTs (Reserve-Conducting Gate-Commutated Thyristors) by novel punch-through (PT) concept with 5,500v rated voltage is described here. A PT and NPT (non punch-through) concept for the same blocking voltage has been compared in detail. The simulation work indicates that GCT with such PT design exhibits that the forward breakdown voltage is 6,400V which is enough for supporting 5500V blocking. Additionally, the real IGCT turn-off in the mode of PNP transistor has been realized. However, the carrier extraction from N-base to gate terminal will be drastic slowly in terms of NPT structure except for the high on-state voltage drop.

• Journal of Information Display
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• 제10권1호
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• pp.16-18
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• 2009

A three-terminal hybrid-aligned nematic liquid crystal (3T-HAN LC) cell capable of fast turn-off switching is proposed in this paper. By employing the relaxation process initiated by an electric-field pulse, a fast turn-off time of less than 1 ms can be obtained through optically hidden relaxation. A low operating voltage and high transmittance were confirmed through simulations and experiments.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.137-140
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• 2000

This paper proposes an improved soft switching two-transistor forward converter which uses a novel lossless snubber circuit to effectively control the turn-off dv/dt rate of the main transistors. In the proposed soft switching implementation the turn-off voltage traces across the main two transistors are almost the same contributing to reduce the total capacitive turn-on loss and the snubber current is divided into the two transistors resulting in distributed thermal stresses

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1527-1536
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• 2014

This paper investigates the optimal values of turn-on and turn-off angles, and ratio of flux linkage at turn-off angle and peak phase current positions of optimal control for accomplishing maximum output power in an 8/6 Switched Reluctance Generator (8/6 SRG). Phase current waveform is analyzed to determine optimal excitation angles (optimal turn-on and turn-off angles) of the SRG for maximum output power which is applied from a nonlinear magnetization curve in terms of control variables (dc bus voltage, shaft speed, and excitation angles). The optimal excitation angles in single pulse mode of operation are proposed via the analytical model. Simulated and experimental results have verified the accuracy of the analytical model.

• 한국전기전자재료학회논문지
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• 제25권7호
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• pp.521-524
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• 2012

We report on variations of electrical properties with different active layer thickness and post-annealing temperature in amorphous In-Ga-Zn-O (IGZO) thin-film transistors (TFTs). In particular, subthreshold swing (SS) of the IGZO-TFTs was improved as increasing the active layer thickness at an given post-annealing temperature, accompanying the negative shift in turn-off voltage. However, as increasing post-annealing temperature, only turn-off voltage was shifted negatively with almost constant SS value. The effect of the active layer thickness and post-annealing temperature on electrical properties, such as SS, field effect mobility and turn-off voltage in IGZO-TFTs has been explained in terms of the variation of trap density in IGZO channel layer and at gate dielectric/IGZO interface.

• Journal of information and communication convergence engineering
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• 제9권3호
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• pp.310-314
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• 2011

This paper has presented doping profile dependent threshold voltage for DGMOSFET using analytical transport model based on Gaussian function. Two dimensional analytical transport model has been derived from Poisson's equation for symmetrical Double Gate MOSFETs(DGMOSFETs). Threshold voltage roll-off is very important short channel effects(SCEs) for nano structures since it determines turn on/off of MOSFETs. Threshold voltage has to be constant with decrease of channel length, but it shows roll-off due to SCEs. This analytical transport model is used to obtain the dependence of threshold voltage on channel doping profile for DGMOSFET profiles. Also we have analyzed threshold voltage for structure of channel such as channel length and gate oxide thickness.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권12호
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• pp.632-640
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• 2003

In conventional Zero-Voltage-Transition(ZVT) PWM converters, zero-voltage turn-on and turn-off for main switch without increasing voltage/current stresses is achieved at a fixed frequency. The switching loss, stress, and noise, however, can't be minimized because they adopt auxiliary switches turned off under hard-switching condition. In this paper, new ZVS-PWM converters of which both active and passive switches are always operating with soft-switching condition are proposed. Therefore, the proposed ZVS-PWM converters are most suitable for avionics applications requiring high-power density. Breadboarded ZVS-PWM boost converters using power MOSFET are constructed to verify theoretical analysis.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.227-230
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• 2002

The switching device in an inductive circuit is stressed by the over-voltage at the turn-off time. Thus if the peak value of the over-voltage is not properly limited, the switching device may be broken. Therefore, the snubber circuit should be added to protect the switching device from the over-voltage. The circuit designer must be familiar with the design of the snubber This paper tests the possibility that TVS instead of the conventional snubber can be applied to the protection circuit of the switching device without using the complicated design equations, and shows that the rating of TVS can be easily selected by considering only several parameters of TVS. The experimental results show the reduced switching voltage of the switching device at the turn-off time.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.153-155
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• 1998

A novel soft-switching pulse-width modulated boost-type DC-DC converter topology is presented in this paper. The conventional boost switch is replaced by a switching cell that is comprised of two switch-diode pairs being linked by an inductor for zero-current switching turn-on. The diodes commutate the current that is flowing through the soft-switching inductor when the two switch turn-off. The capacitor is placed in parallel with the two switches during turn-off, thus providing zero-voltage switching turn-off. Simulation results are presented to support the theoretical considerations.

• 한국정보전자통신기술학회논문지
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• 제6권3호
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• pp.168-173
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• 2013

본 연구는 IGBT(Insulated Gate Bipolar Transistor)의 전기적 특성을 향상시키기 위해 새로운 구조의 IGBT를 제안하였다. 첫 번째 구조는 기존 IGBT 구조의 P-베이스 영역 우측 부분에 N+영역을 추가한 방법으로 기존 구조에 비해 빠른 Turn-off 시간과 낮은 전도 손실을 갖는 구조이다. 또한, 두 번째 구조는 게이트 우측 하단에 P+를 형성함으로써 Latching 전류를 향상시킨 구조이다. 시뮬레이션 결과 제안된 첫 번째 구조는 빠른 Turn-off 시간(3.4us), 낮은 순방향 전압강하(3.08V)의 특성을 보였으며, 두 번째 구조는 높은 Latching 전류(369A/?? ) 특성을 보였다. 따라서 본 논문은 제안된 두 가지의 구조를 하나로 결합한 구조로써 기존 IGBT보다 향상된 특성을 시뮬레이션을 통하여 확인하였다.