• 한국세라믹학회지
• /
• 제34권10호
• /
• pp.1060-1066
• /
• 1997

In this paper, the effects of La addition of PLZT thin film prepared by sol-gel method on the capacitor characteristics are investigated for gigabit generation DRAM applications. The addition of La on the PLZT capacitor results in a trade-off between charge storage density(Qc') and leakage current density(Jl). As La content increases, Qc' and permeability(εr) at 0V are reduced while Jl is significantly decreased. It is demonstrated that 5% La doping of PZT can substantially reduce Jl and also improve resistance to fatigue while incurring only minimal degradation of Qc'. Very low leakage current density (5×10-7 A/㎠ even at 125℃) and high charge storage density (100fC/㎛2) under VDD/2=1V conditions are achieved using 5% La doped PZT thin films for gigabit DRAM capacitor dielectrics. In addition, the fatigue and TDDB measurements indicate good reliability of the PLZT capacitors.

• 조명전기설비학회논문지
• /
• 제18권2호
• /
• pp.150-156
• /
• 2004

단상 전원에 의해 기동되는 영구자석형 단상 동기 전동기는 효율은 높지만, 회전 방향을 결정하기가 어렵다. 본 연구에서는 커패시터 운전 단상 동기 전동기의 기동 특성에 대하여 연구하였다. 고정자는 커패시터 운전 단상 유도기와 동일하지만, 회전자가 영구자석으로 구성된다. 이 경우는 회전자와 고정자 조건에 따라 기동 조건이 결정되고 모터의 회전 방향이 결정될 수 있다. 이 결과에서, 제안된 전동기는 낮은 기동토크를 요구하는 팬과 같은 부하에 적용될 수 있을 것으로 기대된다.

• 한국산학기술학회논문지
• /
• 제13권6호
• /
• pp.2697-2701
• /
• 2012

안티퓨즈 MOS 커패시터를 기반으로 제작된 OTP 소자의 수율은 프로그램 과정에서 입력 저항(Rin)값과 통과 트랜지스터(Pass Tr)의 크기, 데이터 읽기 과정에서 읽기 트랜지스터(Read Tr)와 읽기 전압에 영향을 받는다. 따라서 수율에 영향을 주는 요소를 분석하기 위해 여러 가지 실험 조건을 달리하여 각각의 조건에 대해 블로잉 후 실효소자의 저항 특성에 대한 풀 맵(full map) 데이터를 얻어 OTP 소자가 어떻게 동작하는지를 분석하여 수율 개선에 필요한 최적 조건을 연구하였다. 최적 조건은 입력저항이 $50{\Omega}$, 통과 트랜지스터의 W값이 $10{\mu}m$, 읽기 전압이 2.8 V 일 때이다.

• 전력전자학회논문지
• /
• 제27권4호
• /
• pp.325-331
• /
• 2022

This study proposes a design method that minimizes a conduction loss of LCC resonant converter under rated condition. Through a simplified analysis of the waveform of the resonant current, the power transfer section and RMS value of the resonant current was analyzed mathematically and graphically. Based on this analysis, the design method that minimizes the RMS value of the resonant current is proposed. To demonstrate this method, this study designed a 7.5 kW (100 V, 75 A) capacitor charger based on LCC resonant converter and the design parameters were chosen according to the process of the design method. Then, the capacitor charger was implemented. An experiment was conducted to measure efficiency while satisfying design specifications under rated conditions. This design method was verified to be effective by achieving 97.7% maximum efficiency and design specifications under rated conditions.

• Journal of Electrical Engineering and Technology
• /
• 제8권5호
• /
• pp.1012-1020
• /
• 2013

In this work, Self-adaptive Differential Evolutionary (SaDE) algorithm is proposed to solve Optimal Location and Size of Capacitor (OLSC) problem in radial distribution networks. To obtain the SaDE algorithm, two improvements have been applied on control parameters of mutation and crossover operators. To expand the study, three load conditions have been considered, i.e., constant, varying and effective loads. Objective function is introduced for the load conditions. The annual cost is fitness of problem, in addition to this cost, CPU time, voltage profile, active power loss and total installed capacitor banks and their related costs have been used for comparisons. To confirm the ability of each improvements of SaDE, the improvements are studied both in separate and simultaneous conditions. To verify the effectiveness of the proposed algorithm, it is tested on IEEE 10-bus and 34-bus radial distribution networks and compared with other approaches.

• 전기학회논문지P
• /
• 제61권4호
• /
• pp.186-191
• /
• 2012

DC Bus Electrolytic capacitors have been widely used in power conversion system because they can achieve high capacitance and voltage ratings with volumetric efficiency and low cost. This type of capacitors have been traditionally used for filtering, voltage smoothing, by-pass and other many applications in power conversion circuits requiring a cost effective and volumetric efficiency components. Unfortunately, electrolytic capacitors are some of the weakest components in power electronic converter. Many papers have proposed different methods or algorithms to determinate the ESR and/or capacitance C for fault diagnosis of the electrolytic capacitor. However, both ESR and C vary with frequency and temperature. Accurate knowledge of both values at the capacitors operating conditions is essential to achieve the best reference data of fault judgement. According to parameter analysis, the capacitance increases with temperature and the ESR decreases. Higher frequencies make the ESR and C to decrease. Analysis results show that the proposed electrolytic capacitor parameter estimation technique can be applied to reference signal of capacitor diagnosis systems successfully.

• 한국산업융합학회 논문집
• /
• 제26권6_2호
• /
• pp.1117-1125
• /
• 2023

The DC part of the DC microgrid power conversion system uses capacitors for buffers of charge and discharge energy for smoothing voltage and plays important roles such as high frequency component absorption, power balancing, and voltage ripple reduction. The capacitor uses an aluminum electrolytic capacitor, which has advantages of capacity, low price, and relatively fast charging/discharging characteristics. Aluminum electrolytic capacitors(AEC) have previous advantages, but over time, the capacity of the capacitors decreases due to deterioration and an increase in internal temperature, resulting in a decrease in use efficiency or an accident such as steam extraction due to electrolyte evaporation. It is necessary to take measures to prevent accidents because the failure diagnosis and detection of such capacitors are a very important part of the long-term operation, safety of use, and reliability of the power conversion system because the failure of the capacitor leads to not only a single problem but also a short circuit accident of the power conversion system.

• 전기전자학회논문지
• /
• 제22권4호
• /
• pp.941-947
• /
• 2018

일반적으로 커패시터는 빈번한 충 방전으로 시스템의 수명에 큰 영향을 미친다. 본 논문에서는 고전압, 대전류의 HVDC 서브모듈용 필름 커패시터의 핵심 고장원인을 분석하여 커패시터의 설계 및 제조공정의 주의사항을 분석한다. 먼저 커패시터의 FMEA 수행을 통해 고장원인, 고장모드, 고장영향에 대해 분석한다. 커패시터의 고장에 가장 큰 영향을 주는 고장원인과 영향을 정량적으로 평가하기 위해 커패시터에 대한 고장나무(Fault-tree)를 제시하고 설계인자와 구동환경의 조건에 따른 고장률을 분석한다. 커패시터 고장의 핵심 원인이 커패시턴스 변화에 있음을 확인하고, 커패시터의 고장률 저감을 위해서 커패시터의 설계와 제조공정 중 온도상승, 코로나 발생, 전극팽창, 절연거리 감소를 최소화할 필요가 있음을 검증한다.

• Journal of Electrical Engineering and Technology
• /
• 제11권1호
• /
• pp.100-108
• /
• 2016

This paper presents a simple high efficiency full-bridge DC-DC converter using a series resonant capacitor. The proposed converter achieves the zero voltage switching of the primary switches under a wide range of load conditions and reduces the high circulating current in the freewheeling mode using the leakage resonant inductance and the series resonant capacitor. Thus, the proposed converter overcomes the drawbacks of the conventional full-bridge DC-DC converter and improves its overall system efficiency. Its structure is simplified by using the leakage inductance of the transformer as the resonant inductance and omitting the DC output filter inductance. Also it can operate over a wide range of input voltages. In this paper, the operational principle, analysis and design example are described in detail. Finally, the experimental results from a 650W (24V/27A) prototype are demonstrated to confirm the operation, validity and features of the proposed converter.

• 조명전기설비학회논문지
• /
• 제26권5호
• /
• pp.71-78
• /
• 2012

This paper presents a digital control solution to process capacitor current feedback of high performance single-phase UPS for non-linear loads. In all UPS the goal is to maintain the desired output voltage waveform and RMS value over all unknown load conditions and transient response. The proposed UPS uses instantaneous load voltage and filter capacitor current feedback, which is based on the double regulation loop such as the outer voltage control loop and inner current control loop. The proposed DSP-based digital-controlled PWM inverter system has fast dynamic response and low total harmonic distortion (THD) for nonlinear load. The control system was implemented on a 32bit Floating-point DSP controller TMS320C32 and tested on a 5[KVA] IGBT based inverter switching at 11[Khz]. The validity of the proposed scheme is investigated through simulation and experimental results.