• 한국소음진동공학회논문집
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• 제21권11호
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• pp.997-1004
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• 2011

A fault detection algorithm of a charge and discharge system to ensure the safe use of hybrid electric vehicle is proposed in this paper. This algorithm can be used as a complementary way to existing fault detection technique for a charge and discharge system. The proposed algorithm uses a SVDD technique, which additionally utilizes two methods for learning a large amount of data; one is to incrementally learn a large amount of data, the other one is to remove the data that does not affect the next learning using a new data reduction technique. Removal of data is selected by using lines connecting support vectors. In the proposed method, the data processing speed is drastically improved and the storage space used is remarkably reduced than the conventional methods using the SVDD technique only. A battery data and speed data of a commercial hybrid electrical vehicle are utilized in this study. A fault boundary is produced via SVDD techniques using the input and output in normal operation of the system without using mathematical modeling. A fault detection simulation is performed using both an artificial fault data and the obtained fault boundary via SVDD techniques. In the fault detection simulation, fault detection time via proposed algorithm is compared with that of the peak-peak method. Also the proposed algorithm is revealed to detect fault in the region where conventional peak-peak method is never able to do.

• 문화기술의 융합
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• 제6권4호
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• pp.429-434
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• 2020

전 세계적으로 전기차 판매가 급속도로 증가하고 있으며 이로 인해 환경오염물질 배출(CO2, 질산화물 등)을 줄이는 데 큰 도움이 되고 있다. 하지만 일반적으로 전기차 충전기는 비즈니스 지구 및 주택 지구등을 포함하는 도심 지역에 설치되어 있기에 교외에 거주하는 전기차 사용자들은 정기적 충전 루틴을 확립하기가 매우 어려운 상황이다. 상황 개선을 위해 국내 거주 전기차 사용자들이 손쉽게 접근할 수 있는 거리 범위 내에 위치한 편의점 및 식당(주차장을 보유한) 등과 연계한 생활 밀착형 전기차 충전 서비스를 제안하였다. 사람들이 카페나 식당에서 짬짬이 스마트폰을 충전하는 것처럼 쇼핑과 식사를 하면서 전기차를 충전할 수 있도록 하는 것이 본 서비스가 지향하는 목표이다. 전기차의 충전과 유지보수에 관한 현재 사용자의 니즈를 파악하기 위해 유저 다이어리 연구와 포커스 그룹 인터뷰 연구를 진행하였고, 그 결과를 본 서비스 디자인 개발과정에 적용하였다. 추가적으로 본 서비스가 타게팅하는 상업시설에 손쉽게 설치할 수 있도록 디자인된 두 가지 유형의 충전 장치인 벽걸이형 스마트 소켓 및 폴형 스마트 소켓장치를 설계 및 제작하였다.

• Transactions on Electrical and Electronic Materials
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• 제11권1호
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• pp.42-47
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• 2010

Polymer insulating materials such as cross linked polyethylene (XLPE) are employed in electric cables used for extra high voltage. These materials can degrade due to chemical, mechanical and electric stress, possibly caused by voids, the presence of extrinsic materials and protrusions. Therefore, this study measured discharge patterns, discharge phase angle, quantity and occurrence frequency as well as changes in XLPE under different temperatures and applied voltages. To quantitatively analyze the irregular partial discharge patterns measured, the discharge patterns were examined using a statistical program. A three layer sample was fabricated, wherein the upper and lower layers were composed of non-void XLPE, while the middle layer was composed of an air void and copper particles. After heating to room temperature and $50^{\circ}C$ and $80^{\circ}C$ in silicone oil, partial discharge characteristics were studied by increasing the voltage from the inception voltage to the breakdown voltage. Partial discharge statistical analysis showed that when the K-means clustering was carried out at 9 kV to determine the void discharge characteristics, the amount discharged at low temperatures was small but when the temperature was increased to $80^{\circ}C$, the discharge amount increased to be 5.7 times more than that at room temperature because electric charge injection became easier. An analysis of the kurtosis and the skewness confirmed that positive and negative polarity had counterclockwise and clockwise clustering distribution, respectively. When 5 kV was applied to copper particles, the K-means was conducted as the temperature changed from $50^{\circ}C$ to $80^{\circ}C$. The amount of charge at a positive polarity increased 20.3% and the amount of charge at a negative polarity increased 54.9%. The clustering distribution of a positive polarity and negative polarity showed a straight line in the kurtosis and skewness analyses.

• 전력전자학회논문지
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• 제19권2호
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• pp.139-148
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• 2014

State-of-charge (SOC) is one of the significant indicators to estimate the driving range of the electric vehicle and to control the alternator of the conventional engine vehicles as well. Therefore its precise estimation is crucial not only for utilizing the energy effectively but also preventing critical situations happening to the power train and lengthening the lifetime of the battery. However, lead-acid battery is time-variant, highly nonlinear, and the hysteresis phenomenon causes large errors in estimation SOC of the battery especially under the frequent discharge/charge. This paper proposes a novel estimation technique for the SOC of the Lead-Acid battery by using a well-known Extended Kalman Filter (EKF) and an electrical equivalent circuit model of the Lead-Acid battery considering diffusion and hysteresis characteristics. The diffusion is considered by the reconstruction of the open circuit voltage decay depending on the rest time and the hysteresis effect is modeled by calculating the normalized integration of the charge throughput during the partial cycle. The validity of the proposed algorithm is verified through the experiments.

• 조명전기설비학회논문지
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• 제26권7호
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• pp.16-22
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• 2012

With the increase of consumption of new renewable energy, the use of Electric Double Layer Capacitor(EDLC) is being gradually widened as the next generation energy storage device. In order to expand the market of EDLC which is recently receiving a lot of attraction as a new promising area, development of a charge/discharge cycle tester to measure and test performance, is essential. Therefore, this research designed a circuit to measure capacity and internal resistance and a circuit to measure voltage maintenance properties, based on EDLC's basic charging/discharging properties so it is able to measure the state of charge and discharge at high speed. When evaluating performance characteristics, the 5[V]/100[A] prototype-EDLC charge/discharge testing system developed for this research showed ${\pm}0.1$[%] of accuracy of voltage and current measurement. It was also proved that the developed charge/discharge testing system for EDLC can be applied to the actual industry, when testing the entire system using a program produced for data monitoring and acquisition.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.82.2-82.2
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• 2011

A channel design which is closely related with the mass transport overpotential is one of the most important procedures to optimize the whole fuel cell performance. In this study, three dimensional results of a numerical study for gas distribution in channels of a molten carbonate fuel cell (MCFC) unit cell for a 1kW class stack was presented. The relationship between the fuel and air distribution in the anode and cathode channels of the unit cell and the electric performance was observed. A charge balance model in the electrodes and the electrolyte coupled with a heat transfer model and a fluid flow model in the porous electrodes and the channels was solved for the mass, momentum, energy, species and charge conservation. The electronic and ionic charge balance in the anode and cathode current feeders, the electrolyte and GDEs were solved for using Ohm's law, while Butler-Volmer charge transfer kinetics described the charge transfer current density. The material transport was described by the diffusion and convection equations and Navier-Stokes equations govern the flow in the open channel. It was assumed that heat is produced by the electrochemical reactions and joule heating due to the electrical currents.

• 전기학회논문지
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• 제58권10호
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• pp.2011-2015
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• 2009

In an insulating dielectric liquid such as transformer oil, space charge injection and propagation were analyzed under the Fowler-Nordheim and Richardson-Dushman's thermal emission charge injection conditions for blade-plane electrodes stressed by a step voltage. The governing equations were composed of all five equations such as the Poisson's equation for electric fields, three continuity equations for electrons, negative, and positive ions, and energy balanced equation for temperature distributions. The governing equations for each carrier, the continuity equations, belong to the hyperbolic-type PDE of which the solution has a step change at the space charge front resulting in numerical instabilities. To decrease these instabilities, the governing equations were solved simultaneously by the Finite Element Method (FEM) employing the artificial diffusion scheme as a stabilization technique. Additionally, the terminal current was calculated by using the generalized energy method which is based on the Poynting's theorem, and represents more reliable and stable approach for evaluating discharge current. To verify the proposed method, the discharge phenomena were successfully applied to the blade~plane electrodes, where the radius of blade cap was $50{\mu}m$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1984-1985
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• 2007

Polyimide is widely used as a high-temperature insulating material. Space charge distributions in polyimide (PI) films strongly depend upon electric field, temperature, water content and so on. We observed space charge distributions in PI films with various water contents. When a dc field was applied to as-received PI films or water-treated PI films, positive and negative homo space charges were observed near the respective electrodes at 333 K. In dried PI films, the homo space charges were much reduced, and positive and negative hetero space charges in the bulk were clearly observed. The space charge amounts in water-treated PI films were smaller than in as-received ones, while the current density in water-treated PI film was larger than that in as-received one by two or more orders of magnitude. These suggest not only that the charge injection from the electrode is enhanced by absorbed water but also that absorbed water makes carriers mobile. The decay of space charge was also faster in water-treated PI than in as-received or dried one. This also supports the enhancement of apparent mobilities of carriers in PI by absorbed water.

• 디지털융복합연구
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• 제18권11호
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• pp.241-246
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• 2020

본 논문에서는 해양 전기추진 시스템과 딥러닝 알고리즘을 융합하여 전기추진 리제너레이션 시스템에서 DC/DC 컨버터 출력 전류 예측 및 리제너레이션 수행 시 배터리 충전량을 예측하기 위해 신경망 모델을 제안한다. 제안 된 신경망을 실험하기 위해 PCM의 입력 전압과 전류를 측정하고 시제품 PCM 보드의 출력 결과를 통해 데이터 세트를 구성하였다. 또한 불충분 한 데이터 세트에서 학습 결과를 향상시키기 위해 기존 데이터 세트를 데이터 피팅하여 학습을 진행하였다. 학습 후 신경망 모델의 데이터 예측 결과와 실제 측정 데이터의 차이를 그래프를 통해 확인하였다. 제안한 신경망 모델은 입력 전압과 전류 변화에 따른 배터리 충전량 예측을 효율적으로 보여주었다. 또한, DC/DC 컨버터를 구성하는 아날로그 회로의 특성변화를 신경망을 통하여 예측함으로써, 리제너레이션 시스템의 설계 시, 아날로그 회로의 특성을 고려해야 할 것으로 판단된다.

• E2M - 전기 전자와 첨단 소재
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• 제10권3호
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• pp.239-246
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• 1997

The ZnO is stabilize dielectric constant over a broad temperature range because its addition makes the relaxation time short. In this study, the composite oxide material (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_{3}$ was mixed by ZnO additive material and the dielectric polarization characteristics was studied. The relative density was over 90[%] at all specimen in the structural characteristics. Among of the specimen, the relative density of (B $a_{0.85}$ $Ca_{0.15}$)Ti $O_{3}$ with ZnO (0.4mol) has a 95[%]. The grain size of composite oxide material with an increasing ZnO increased and it was 1.0[.mu.m]-1.22[.mu.m]. In the electrical characteristics, the charge and discharge current was increased by ZnO addition. The dielectric relaxation time was increased by space charge polarization at above 110[.deg. C] and the dielectric relaxation time was fixed by space charge polarization of para-dielectric layer at below 110[.deg. C]. The dielectric relaxation time was maximum when the grain size was small. The dielectric relaxation time is decreased with an additive material ZnO and interface polarization, existing void at the grain and grain boundary. The remnant polarization is increased and the coercive electric field is decreased by ZnO.