• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.273-275
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• 1998

This paper presents a method of determining the minimum amount of reactive power capacity installation and minimizing transmission line losses. It deals with maintaining voltage profile within an acceptable range with respect to the increase in load demand. Our approach provides three-different stages to power system planner. First stage considers existing capacitors. Second stage considers expanding the size of the installed capacitors. Third stage considers existing capacitors and newly installed capacitors whose locations are irrelevant to the locations of existing ones. Validity and effectiveness of the proposed algorithm are confirmed by results on modified New England 30 bus test system.

• 한국통신학회논문지
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• 제7권1호
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• pp.10-17
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• 1982

최근 switched capacitors 및 고정 capacitors와 능동소자를 利用한 analong 여파기 실현에 큰 관심을 갖게 되었다. Switched capacitor는 저항에 비해 온도특성 및 선형특성이 양호할 뿐 아니라 Si chip 면적이 훨씬 적게 소요되고 MOS기술에 의해 완전 IC화가 가능하다. 본 논문에서는 저항과 switched capacitor를 사용해 Gyrator 여파기내의 모든 저항을 switched capacitor로 대친시킬 SC-Gyrator 여파기를 실현했다. 실험결과 Gyrator여파기와 SC-Gyrator 여파기의 특성이 만족할 만큼 일치함을 확인했다.

• 전기학회논문지P
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• 제58권4호
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• pp.391-396
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• 2009

In this paper, a control algorithm for DC-Link voltage unbalancing compensation of a four-switch inverter for a three-phase BLDC motor drive is proposed. Compared with a conventional six-switch inverter, the split source of the four-switch inverter can be obtained by splitting DC-link capacitor into two capacitors to drive the three phase BLDC motor. The voltages across each of two capacitors are not always equal in steady state because of the unbalance in the impedance of the DC-link capacitors $C_1$ and $C_2$ or the variable current flowed into the capacitor's neutral point in motor control. Despite the unbalance, if the BLDC motor may be run for a long time the voltage across one of the capacitors is more increased. So the unbalance in the capacitors voltages will be accelerated. As a result, The current ripple and torque ripple is increased due to the fluctuation of input current which flows into 3-phase BLDC motor. According to that, the vibration of motor will be increased and the whole system will be instable. This paper presents a control algorithm for DC-Link voltage unbalancing compensation. The sampling from the voltages across each of two capacitors is used to perform the voltage control of DC-Link by using the feedforward controller.

• 전기학회논문지
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• 제65권1호
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• pp.97-102
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• 2016

In this paper, a bidirectional power supply charger is proposed. This system used a solar cell panel to generate electricity and used super capacitors to store these energies, which can be used for the robot cleaner or some other electronic products. This system include a phase-shift controlled bidirectional dual active bridge (DAB) converter, solar panel super capacitors and DSP controller. In the daytime it can charge to the super capacitors to store the energy generated by the solar cell panel and in the night it will release the energy stored in the super capacitors to loads. A prototype of the proposed bidirectional power supply charger system was designed which can achieve 18V to 30V input, 10V/20W output to super capacitors and 9V/6.5W output when it acts as a charger for the robot cleaner. The system is verified to be sTable and reliable by both the simulation and experimental results.

• Journal of Electrochemical Science and Technology
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• 제8권2호
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• pp.107-114
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• 2017

Pseudo capacitors belong to one group of super capacitors which are consisted with non carbon based electrodes. As such, conducting polymers and metal oxide materials have been employed for pseudo capacitors. Conducting polymer based pseudo capacitors have received a great attention due to their interesting features such as flexibility, low cost and ease of synthesis. Much work has been done using liquid electrolytes for those pseudo capacitors but has undergone various drawbacks. It has now been realized the use of solid polymer electrolytes as an alternative. Among them gel polymer electrolytes (GPEs) are in a key place due to their high ambient temperature conductivities as well as suitable mechanical properties. In this study, composition of a polyacrylonitrile (PAN) based GPE was optimized and it was employed as the electrolyte in a pseudo capacitor having polypyrrole (PPy) electrodes. GPE was prepared using ethylene carbonate (EC), propylene carbonate (PC), sodium thiocyanate (NaSCN) and PAN as starting materials. The maximum room temperature conductivity of the GPE was $1.92{\times}10^{-3}Scm^{-1}$ for the composition 202.5 PAN : 500 EC : 500 PC : 35 NaSCN (by weight). Performance of the pseudo capacitor was investigated using Cyclic Voltammetry technique, Electrochemical Impedance Spectroscopy (EIS) technique and Continuous Charge Discharge (GCD) test. The single electrode specific capacity (Cs) was found out to be 174.31 F/g using Cyclic Voltammetry technique at the scan rate of 10 mV/s and within the potential window -1.2 V to 1.2 V. The same value obtained using EIS was about 84 F/g. The discharge capacity ($C_d$) was 69.8 F/g. The capacity fade over 1000 cycles was rather a low value of 4%. The results proved the suitability of the pseudo capacitor for improving the performance further.

• 전기의세계
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• 제15권5호
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• pp.25-31
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• 1966

This paper derives the useful formulas for computing annual profits, and economical size, locations and regulating values of parallel shunt capacitors in case that they are installed in a distribution line. Inparticular, the derived formulas consider the influence of load variations in order to represent the actual load situations.

• 대한전자공학회논문지SD
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• 제41권5호
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• pp.99-105
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• 2004

더미 비트라인을 이용한 공유 커패시터 전하공유 롬(shared-capacitor charge-sharing ROM SCCS-ROM)이 제안되었다. SCCS-ROM은 기존의 전하공유 롬(charge-sharing ROM, CS-ROM)의 전하공유 기법으로 비트라인의 스윙전압을 줄였다. CS-ROM에서는 출력 비트 마다 3개의 작은 커패시턴스들이 필요하지만, 제안된 SCCS-ROM은 그 커패시터들을 공유함으로써 필요한 커패시터의 수를 단지 3개로 줄였다. 또한, 더미 비트라인들(dummy bit lines)로 커패시터들을 구현함으로써, 잡음내성을 증가시켰을 뿐만 아니라 소모전력 또한 줄였다. 8K×15bi1s의 SCCS-ROM이 0.35㎛ CMOS 공정으로 구현되었다. SCCS-ROM은 3.3V의 100㎒ 동작에서 8.63㎽의 전력을 소모하였다. 시뮬레이션에서 SCCS-ROM은 CS-ROM보다 8.4% 적은 전력을 소모하였다.

• 전기학회논문지P
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• 제66권4호
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• pp.236-241
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• 2017

This paper presents a single-phase grid connected voltage-ed inverter with a power decoupling circuit. In the single-phase grid connected voltage-ed inverter, it is well known that a power pulsation with twice the grid frequency is contained in the input power. In a conventional voltage type inverter, electrolytic capacitors with large capacitance have been used in order to smooth the DC voltage. However, lifetime of those capacitors is shortened by the power pulsation with twice grid frequency. The authors have been studied a active power decoupling(APD) method that reduce the pulsating power on the input DC bus line, this enables to transfer the ripple energy appeared on the input DC capacitors into the energy in a small film capacitor on the additional circuit. Hence, extension of the lifetime of the inverter can be expected because the small film capacitor substitutes for the large electrolytic capacitors. Finally, simulation and experimental results are discussed.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권12호
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• pp.624-631
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• 2003

This paper presents a simple carrier symmetric method for the voltage balance of flying capacitors in FCMLI(flying capacitor multi-level inverter). To achieve the voltage balance of flying capacitors, the utilization of each carrier must be balanced during a half-cycle of the switching period such as PSPWM(Phase-Shifted PWM). However, the CRPWM(Carrier Redistribution PWM) method causes the fluctuation of flying capacitor voltages because the balanced utilization of carriers is not achieved. Moreover, it does not consider that the load current change has an influence on flying capacitor voltages by assuming that the current flows into the load. To overcome the drawbacks of CRPWM, it is modified by the technique that carriers of each band are disposed symmetrically at every fundamental period. Firstly, the CRPWM method is reviewed and the theory on voltage balance of flying capacitors is analyzed. The proposed method is introduced and is verified through the experiment result.

• 한국전기전자재료학회논문지
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• 제17권12호
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• pp.1283-1288
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• 2004

Metal-ferroelectric-insulator-semiconductor(WFIS) capacitors using rapid thermal annealed LiNbO$_3$/AlN/Si(100) structure were fabricated and demonstrated nonvolatile memory operations. The capacitors on highly doped Si wafer showed hysteresis behavior like a butterfly shape due to the ferroelectric nature of the LiNbO$_3$ films. The typical dielectric constant value of LiNbO$_3$ film in the MFIS device was about 27, The gate leakage current density of the MFIS capacitor was 10$^{-9}$ A/cm$^2$ order at the electric field of 500 kV/cm. The typical measured remnant polarization(2P$_{r}$) and coercive filed(Ec) values were about 1.2 $\mu$C/cm$^2$ and 120 kV/cm, respectively The ferroelectric capacitors showed no polarization degradation up to 10$^{11}$ switching cycles when subjected to symmetric bipolar voltage pulses of 1 MHz. The switching charges degraded only by 10 % of their initial values after 4 days at room temperature.e.