• Journal of the Korean Electrochemical Society
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• v.5 no.1
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• pp.27-29
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• 2002

We report a fuel cell power supply unit for mobile phone which operates at room temperature and ambient pressure using liquid methanol and air. The unit consists of a direct methanol fuel cell (DMFC) and a back-up battery connected parallely to the fuel cell. DMFC supplies half of the required power and the back-up battery supplies the other half during talk mode. In standby mode, DMFC covers $100\%$ of the required power and charges the back-up battery as well, Eight unit cells, each having $9 cm^2$ of active area, were connected in series in order to raise the output volotage to $2.5\~3.9V$, which is typical for most mobile phones.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1998.11a
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• pp.177-180
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• 1998

To manage lead-acid battery efficiently and to use it longer in UPS, the state of charge(SOC) indicator of the battery is needed. So a new approach to developing battery SOC indicator for UPS is discussed in this paper. This method to determining SOC by combining the available data of discharge characteristics of a battery with neural networks(NN) is presented. The 3-layered NN with back propagation algorithm has been used. Exprement results show that the proposed method is appropriate as SOC indicator of the battery.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.4
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• pp.100-105
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• 1998

This paper proposes a new control strategy of bidirectional uninterruptible power supply (UPS) with the performance of active power filter which compensates the harmonics and reactive power. With only one power stage, it is working simultaneously as the AC/DC rectifier/battery charger and DC/AC inverter to the operation of battery charging or back-up power supplying. Therefore the operation of the proposed system can be divided into the modes, such as the active power filter mode and the battery back-up power mode. And a novel closed-loop control strategy is used to calculate the reference current. The performance of the proposed 5[kVA] system is verified by the simulation and experimental results.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.202-206
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• 1990

The existing batteries such as lead acid battery and Nicad battery have been at serious issue, because heavy metal such as Pb and Cd give rise to environmental pollution. Therefor, when these material is changed over polymeric electroactive material, we expect environmental pollution will be prevented. We decided to develop 2025 coin type PAn/Li-Al secondary battery for goal of memory back-up battery. This report is concerned with manufacturing of 2025 coin type PAn/Li -Al secondary battery.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1009-1011
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• 2002

Some defective cells in the battery bank of power systems using batteries result in deterioration of the performance of the total battery bank. Consequently, the battery bank can't perfectly back up the system in occurrence of any power problems and the overcharge of defective cells may lead to their explosion or the occurrence of fire. The developed battery management system in this study enables operators to telemeter and analyze internal resistance, voltages, currents, and temperatures of batteries at remote sites through a PC, so they can detect defective cells before the occurrence of power problems. And adoption of this system ensures extension of battery life.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.222-226
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• 2001

본 논문에서는 단상 H-bridge 구조의 VSC (Voltage Source Converter)를 이용하여 계통전원을 사용하는 부하의 고조파 전류 보상기능과 전원 Back-up 기능을 갖는 부하전력보상기를 보여준다. 이 두 제어 기능은 전원전압의 유무에 따라 APF의 컨버터 동작과 UPS의 인버터로 동작하게 함으로써 기존 UPS에 부하 전류의 고조파 보상이라는 부가적인 이득을 갖는 이중전력보상기(Dual Function Power Compensator)라 할 수 있다. 컨버터 제어는 Battery 충전 동작과 APF 동작을 동시에 수행하며, 인버터 제어는 정전시 부하에 전원을 공급하는 UPS로서의 동작을 수행하게 된다. 두가지 동작이 성공적으로 수행되기 위해서는 1. 전원전압의 신속한 검출과 판단, 2. 컨버터의 Battery 충전, 3. APF동작을 위한 부하전류의 고조파 전류계산, 4. 전원전압의 동기추종 등이 각각의 동작모드별로 순조롭게 연계동작 되어 야 한다. 본 논문에서는 DFPC의 발생배경과 제안된 DFPC 제어모드의 구분을 결정하는 전원전압의 검출방법에 대하여 소개한다. 그리고 제안된 DFPC의 실제 시스템을 제작하여 각각의 동작상황과 성능을 시험하여 그 결과를 보여준다.

• Journal of IKEEE
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• v.23 no.2
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• pp.580-585
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• 2019

Batteries are being used in ESS, electric vehicles and uninterruptible power backup systems. Lead-acid batteries are the most used batteries for high capacity power back up equipment due to their high reliability and low price advantages. It is very important to estimate the chargeable capacity(SoH), and many algorithms were proposed to estimate the internal resistance of the battery. In this paper, the Battery Monitoring System(BMS) for high capacity uninterruptible power supply for IDC is proposed. A simple algorithm for estimating internal resistance was proposed. An computational block diagram of the proposed signal processing algorithm and BMS system configuration of CPU and analog circuit were shown. The proposed method was proved useful by presenting data examples of application to actual IDC sites.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.252-253
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• 2010

본 논문에서는 Molten Carbonate Fuel Cell (MCFC)의 느린 동특성을 Load Leveler와 2차 전지로 구성된 back-up 시스템으로 보완하여 독립운전을 가능하게 한 대용량 연료전지 발전시스템을 제안한다. 제안한 독립운전 시스템의 발전 용량 및 battery 용량은 실제 전력사용 통계자료를 근거로 최적으로 산정되며, 컴퓨터 시뮬레이션을 통하여 타당성을 검증한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.27-34
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• 2014

The paper proposed a sizing method of an energy storage system(ESS) for peak shaving of high-speed railway substations based on load profile patterns of substations. A lithium based battery ESS was selected since it can produce high-power at high speed that peak shaving requires, and also takes up a relatively smaller space for installation. Adequate size of the ESS, minimum capacity which can technically meet a peak shaving target, was determined by collectively considering load patterns of a target substation, characteristics of the ESS to be installed, and optimal scheduling of the ESS. In case study, a local substation was considered to demonstrate the proposed sizing method. Also economic analysis with the determined size of ESS was performed to calculate electricity cost savings of the peak shaving ESS, and to offer pay-back period and return on investment.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.5
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• pp.539-544
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• 2022

This research shows the test performance of a 6 kW-scale hybrid electric power system for the high endurance drone. The power system is composed of a two-stroke reciprocal engine, starter-generator and battery, and they are integrated as one power unit. The engine is designed to provide the house for holding the starter-generator at the end of a crankshaft in turn the engine and starter-generator can maintain the same speed during the operational period. In this way, the generated power is readily controlled by just manipulating an engine throttle movement. Moreover, the starter-generator can initiate an engine operation with an aid of battery power until the combustion process becomes stabilized. In consequence, integration mechanism between an engine and generator is simplified, which results in weight reduction achieved. The duty of back-up battery is to provide a starting power to generator via a system controller in addition to covering momentarily power shortage. Therefore, the electric power system is vindicated to provide 6 kW power through a ground test.