• Journal of international Conference on Electrical Machines and Systems
• /
• 제3권2호
• /
• pp.169-175
• /
• 2014

This paper presents an improved direct power control (DPC) strategy for grid-connected voltage source inverter (VSI) under unbalanced and harmonic grid voltage conditions. Based on the mathematic model of VSI with the negative sequence, 5th and 7th harmonic voltage components consideration, a PI controller is used in the proposed DPC strategy to achieve the average output power regulation. Furthermore, vector PI controller with the resonant frequency tuned at the two times and six times grid fundamental frequency is adopted to regulate both negative and harmonic components, and then two alternative targets of the balanced/sinusoidal current and smooth active/reactive output power can be achieved. Finally, simulation results based on MATLAB validate the availability of the proposed DPC strategy.

• Journal of Electrical Engineering and Technology
• /
• 제6권4호
• /
• pp.505-512
• /
• 2011

A novel passive boost power converter forsingle-phaseswitched reluctance motor is presented. A simple passive circuit is proposed comprisingthree diodes and one capacitor. The passive circuitis added in the front-end of a conventional asymmetric converter to obtain high negative bias. Based on this passive network, the terminal voltage of the converter side is a general DC-link voltage level in parallel mode up to a double DC-link voltage level in series mode. Thus,it can suppress the negative torque generation from the tail current and improve the output power. The results of the comparative simulation and experiments forthe conventional and proposed converter verify the performance of the proposed converter.

• 대한전자공학회논문지
• /
• 제20권1호
• /
• pp.45-49
• /
• 1983

Metal/insulator/n epi-layer/p+구조의 CID(controlled inversion device)를 제조하였다. I-V 특성 곡선에서 ON상태와 OFF상태사이에 부성저항(negative resistance)영역이 나타났다. CID를 제조하기 위해서 행한 산화층 형성 과정에서 600℃에서 5분간 산화시킨 소자의 스위칭 및 홀딩 전압은 각각 5.0V와 2.5V였다. 그리고 입사된 광에 의해서 스위칭 전압은 감소하였으나 홀딩 전압은 변하지 않았다.

• ETRI Journal
• /
• 제32권3호
• /
• pp.406-413
• /
• 2010

In order to guarantee the proper operation of a recessed channel array transistor (RCAT) pseudo SRAM, the back-bias voltage must be changed in response to changes in temperature. Due to cell drivability and leakage current, the obtainable back-bias range also changes with temperature. This paper presents a pseudo SRAM for mobile applications with an adaptive back-bias voltage generator with a negative temperature dependency (NTD) using an NTD VBB detector. The proposed scheme is implemented using the Samsung 100 nm RCAT pseudo SRAM process technology. Experimental results show that the proposed VBB generator has a negative temperature dependency of -0.85 $mV/^{\circ}C$, and its static current consumption is found to be only 0.83 ${\mu}A$@2.0 V.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
• /
• pp.461-464
• /
• 1999

This study has been investigated that traps generated inside of the oxide and at the oxide interfaces by the stress bias voltage. The traps are charged near the cathode with negative charge and charged near the anode with positive charge. The charge state of the traps can easily be changed by application of low voltages after the stress high voltage. These trap generation involve either electron impact ionization processes or high field generation processes. It determined to the relative traps locations inside the oxides ranges from 113.4$\AA$ to 814$\AA$ with capacitor areas of 10$^{-3}$ $\textrm{cm}^2$ . The oxide charge state of traps generated by the stress high voltage contain either a positive or a negative charge.

• 전기학회논문지
• /
• 제65권8호
• /
• pp.1355-1361
• /
• 2016

The inter-turn fault (ITF) causes the negative sequence components in the d -q voltage equation due to an increase in the unbalance of three-phase input currents. For this reason, d -q voltage equation become complicate as the voltage equation is classified into positive and negative components. In this study, we propose a simplified d -q equivalent circuit of an interior permanent magnet synchronous motor under ITF state. First, we proposed modeling method for d -q current based on the finite element method simulation results. Then, we developed the simplified d -q equivalent circuit by applying the proposed d -q current modeling.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 제38회 하계학술대회
• /
• pp.1455-1456
• /
• 2007

This paper presents the experimental results on impulse breakdown characteristics under a highly non-uniform electric field in $SF_{6}/N_{2}$ gas mixtures according to a change in temperature. Test temperature ranges from $-25^{\circ}C$ to $25^{\circ}C$. The impulse predischarge breakdown developments are investigated by the measurements of current pulse and discharge luminous events. As a result, the predischarge development mechanisms for both positive and negative polarities are same. When increasing the temperature, breakdown voltage due to lightning impulse voltage is increased in negative polarity. On the other hand, when increasing the temperature, breakdown voltage due to lightning impulse voltage is not changed in positive polarity.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2016년도 추계학술대회 논문집
• /
• pp.143-144
• /
• 2016

The circulating current control within the phase legs is one of the main control objectives in a modular multilevel converter (MMC) under different operating conditions. This paper proposes a control strategy of circulating currents in the MMC under unbalanced voltage by using a proportional-resonant (PR) controller. Under the unbalanced voltage, the circulating currents in the MMC consists of three components such as positive-sequence, negative-sequence, and zero-sequence circulating currents. With the PR controller, all components of the circulating current will be directly controlled in the stationary reference frame without decomposing into positive- and negative-sequence components. Thus, the ripples in the circulating currents and the DC current are suppressed under the unbalanced voltage. The effectiveness of the proposed method is verified by simulation results based on PSCAD/EMTDC simulation program.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.97-100
• /
• 2009

A negative waveform was studied to improve the driving characteristics of reset and address periods in ac PDP. Comparative experiments between negative and conventional positive waveforms were performed with 42-inch XGA PDP module. The negative waveform showed lower breakdown voltage than the conventional positive waveform in reset period. Due to its weak and stable discharge during reset period, the contrast ratio was improved by decreasing the black luminance. During address period, the discharge time-lag was measured. The formative time lag ($=T_f$) of negative waveform was improved about 22.8% than $T_f$ of conventional positive waveform.

• 한국진공학회지
• /
• 제14권1호
• /
• pp.17-23
• /
• 2005

본 논문은 글로우방전 질량분석법(Glow Discharge Mass Spectrometry: GDMS)을 이용하여 구리 박막내의 미량 불순물의 농도분석과 음의 기판 바이어스에 대한 구리 박막내의 불순물의 농도변화에 대해서 고찰하였다. 구리 박막은 실리콘 기판 위에 비질량 분리형 이온빔 증착장비를 이용하여 기판 바이어스를 걸지 않은 경우와 -50 V의 기판 바이어스를 걸은 상태에서 증착하였다. 전기를 통하지 않는 분석 샘플의 경우, 직류(DC) GDMS에 의한 분석시, 샘플 표면에서의 charge-up 효과에 의해 분석에 어려움이 있었지만, 본 실험에서는 간편하게 분석이 가능하도록 샘플을 알루미늄 포일(foil)로 감싸서 구리 박막으로부터 실리콘 기판 뒤의 샘플 홀더까지 전기적 접촉이 이루어지도록 하였다. 구리 타겟과 증착된 구리 박막들에 대한 GDMS 분석결과에 의해서, 전체적으로 박막내의 불순물의 양이 음의 기판 바이어스에 의해 줄어듦으로써 구리 박막의 전체 순도를 높일 수 있다는 것을 알게 되었다. 음의 기판 바이어스에 의한 불순물들의 농도변화는 각각의 불순물의 이온화 포텐셜의 차이에 의한 것으로, 박막 증착시 플라즈마내의 Penning ionization effect와 본 논문에서 제시한 이온화 과정에 의해 각 불순물의 농도변화가 설명되어질 수 있었다. 또한, 기판 위에서의 구리 이온들의 충격에 의한 cleaning effect도 박막내의 불순물의 농도변화에 기여했다고 판단된다.