• Journal of the Korean Solar Energy Society
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• v.24 no.2
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• pp.1-7
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• 2004

In this paper, the new improved method for photovoltaic system was studied available for a lighting load by measuring the state of charge of lead-acid batteries. Photovoltaic systems has been evaluated as one of the most new and renewable energy and especially, the Stand-Alone Photovoltaic system has been used to a street light, a road sign light, an air caution light, an emergency call. Many Stand-Alone PV system are installed by a group. Although the pre-installation cost of PV system is high and it has not been operated due to the absence of optimal management standards. In this paper, it is proposed a new operating method by the measurement of lead-acid battery's SOC with a Ah balancing.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.12
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• pp.1021-1027
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• 2012

In this paper, multi-string power balancing system for streetlight was developed. Accordingly, the components of the system was developed, unit converters, MPPT control unit, a bank of Li-ion battery and controls the charging and discharging. Loss by improving the efficiency of the system through the parallel operation of the unit converter output will be reduced. And by improving the efficiency of the system through the unit converter parallel operation, output losses will be reduced. Charging and discharging efficiency of the device used in a typical solar streetlight is calculated based on the maximum power input. Because of the variation of the input power has a weakness. In this paper, flexible to changes in the input, and a system was developed to minimize the cost per watt. Measure the performance of the unit module from the system, the result was more than 91%. And the charging capacity 12 V/105 Ah, module power 180 W, respectively. Should expect to be able to improve performance through continuous monitoring in the future.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.121-122
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• 2015

본 논문은 학생 캡스톤디자인 작품제작의 결과를 정리한 것으로 MCU와 적외선 거리센서를 이용하여 공의 수평위치를 측정하고 이에 따라 양단 서보모터의 각도를 조절하여 공이 중앙에 위치하도록 자동으로 제어하는 볼 밸런서의 구현방법에 대해 소개한다. 탁구공의 위치를 적외선 거리센서로 측정하고 MCU에 PID 제어기 기반의 자동제어 알고리즘을 구현하여 DC서보모터의 각도를 제어함으로써 탁구공이 중앙에 위치하도록 자동으로 제어한다.

• Proceedings of the Korea Contents Association Conference
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• 2016.05a
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• pp.251-252
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• 2016

The vast majority of the disaster prevention design research in Korea has focused on the macro-level interventions such as examining the existing systems and approaches, instituting revised policies, systematically establishing intervention programs, and evaluating the effectiveness of the interventions. However, little has focused on systematically challenging individuals' awareness using micro-level intervention. The present paper introduces approaches to micro-level intervention by infusing narrative-based simulation, and further suggests the implications on balancing the approaches of both micro-level and macro-level interventions.

• 한국전기화학회:학술대회논문집
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• 1998.12a
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• pp.7-27
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• 1998

In order to design capacity of lithium ion battery, some calculations were carried out based on the characteristics of materials by the given battery shape and dimension. The principle of design was built by the interpretation of the correlation of material, electrochemical and battery factors. Parameters of materials are fundamental physical properties of constituent such as cathode. separator, anode, current collectors and electrolyte. Electrochemical factor includes potential pattern as a function of specific capacity, specific discharge capacity(or initial irreversible specific capacity or Ah efficiency) as a function of specific charge capacity and material balancing. Parameters of battery are dimension, construction hardware and performance. Battery capacity was simulated for a lithium cobalt dioxide as cathode and a hard carbon as anode to achieve 1100 mAh for the charge limit voltage of 4.2V, the weight ratio(+/-) of 2.4 and ICR18650. A fabricated test cell (ICR18650) which have weight ratio(+/-) of 2.4 discharged to 1093 mAh for the charge limit voltage of 4.2V. The sequential discharge capacity show good correspondence with designed capacity.

• Carbon letters
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• v.1 no.3_4
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• pp.148-153
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• 2001

The initial irreversible capacity, $Q_i$, is one of the parameters to express the material balancing of the cathode to anode. We introduced new terms, which are the initial intercalation Ah efficiency (IIE) and the initial irreversible specific capacity at the surface ($Q_{is}$), to express precisely the irreversibility of an electrode/electrolyte system. Two terms depended on kinds of active-materials and compositions of the electrode, but did not change with charging state. MPCF had the highest value of IIE and the lowest value of $Q_{is}$ in 1M $LiPE_6$/EC + DEC (1 : 1 volume ratio) electrolyte. IIE value of $LiCoO_2$ electrode was 97-98%, although the preparation condition of the material and the electrolyte were different. $Q_{is}$ value of $LiCoO_2$ was 0~1 mAh/g. MPCF-$LiCoO_2$ cell system had the lowest of the latent capacity. $Q_{is}$ value increased slightly by adding conductive material. IIE and $Q_{is}$ value varied with the electrolyte. By introducing PC to EC+DEC mixed solvent, IIE values were retained, but $Q_{is}$ increased. In case of addition of MP, IIE value increased and $Q_{is}$ value also increased a little.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.477-477
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• 2009

Bimodal Tram developed by KRRI is driven by a series Hybrid propulsion system which has both the CNG engine, generator and LPB(Lithium Polymer Battery) pack. It has three driving modes; Hybrid mode, Engine mode and Battery mode. Even in case of Battery mode, LPB pack to get enough power to drive the vehicle only by itself onsists of 168 LPB cells(80Ah per lcell), 650V. It is important thing to manage LPB pack in a right way, which will extend the lifetime of LPB cells and operate in the hybrid mode effectively. This paper has shown the development of battery management system(12 BMS, 1 BMS per 14cells) to manage LPB pack which is connected with CAN(Controller Area Network) each other and measure the voltage, current, temperature and also control the cooling fan inside of LPB pack. Using the measured data, BMS can show the SOC(State of Charge), SOH(State of Health) and other status of LPB pack including of the cell balancing.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.4
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• pp.231-235
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• 2015

Bimodal Tram developed by KRRI is driven by a series Hybrid propulsion system which has both the CNG engine, generator and LPB(Lithium Polymer Battery) pack. It has three driving modes; Hybrid mode, Engine mode and Battery mode. Even in case of Battery mode, LPB pack to get enough power to drive the vehicle only by itself onsists of 168 LPB cells(80Ah per lcell), 650V. It is important thing to manage LPB pack in a right way, which will extend the lifetime of LPB cells and operate in the hybrid mode effectively. This paper has shown the development of battery management system(12 BMS, 1 BMS per 14cells) to manage LPB pack which is connected with CAN(Controller Area Network) each other and measure the voltage, current, temperature and also control the cooling fan inside of LPB pack. Using the measured data, BMS can show the SOC(State of Charge), SOH(State of Health) and other status of LPB pack including of the cell balancing.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.4
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• pp.99-107
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• 2017

This paper proposes a battery model coefficient correction method for improving the accuracy of existing lithium battery equivalent models. BMS(battery management system) has been researched and developed to minimize shortening of battery life by keeping SOC(state of charge) and state of charge of lithium battery used in various industrial fields such as EV. However, the cell balancing operation based on the battery cell voltage can not follow the SOC change due to the internal resistance and the capacitor. Various battery equivalent models have been studied for estimation of battery SOC according to the internal resistance of the battery and capacitors. However, it is difficult to apply the same to all the batteries, and it tis difficult to estimate the battery state in the transient state. The existing battery electrical equivalent model study simulates charging and discharging dynamic characteristics of one kind of battery with error rate of 5~10% and it is not suitable to apply to actual battery having different electric characteristics. Therefore, this paper proposes a battery model coefficient correction algorithm that is suitable for real battery operating environments with different models and capacities, and can simulate dynamic characteristics with an error rate of less than 5%. To verify proposed battery model coefficient calibration method, a lithium battery of 3.7V rated voltage, 280 mAh, 1600 mAh capacity used, and a two stage RC tank model was used as an electrical equivalent model of a lithium battery. The battery charge/discharge test and model verification were performed using four C-rate of 0.25C, 0.5C, 0.75C, and 1C. The proposed battery model coefficient correction algorithm was applied to two battery models, The error rate of the discharge characteristics and the transient state characteristics is 2.13% at the maximum.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.420-421
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• 2010

In this paper, a multi-module selective battery equalizer for series-connected Li-ion battery pack is proposed. Selective Equalizer (SE) scheme achieves smaller volume and lighter weight than individual cell equalizer (ICE) by minimizing the part count of bulky circuit element. However, SE scheme shows slow balancing speed when the voltage imbalance simultaneously occurs in more than one cell. The proposed multi-module overcomes the problem by employing multiple power converters. Prototype hardware is implemented and experimented with 14Ah battery cells to validate the performance of the proposed equalizer.