• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.2
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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.

• Journal of Power System Engineering
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• v.15 no.2
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• pp.78-83
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• 2011

This paper aims at investigation some operating characteristics and energy usage efficiency of a induction motor and a BLDC motor considering electric propulsion system in a small ship based on battery source. At first, performance curves of discharge voltage from the battery and current from each motor according to the load variations were analyzed. Next, variations of motor torque and rotational speed versus load change at each motor were analyzed. Finally, efficiency of energy usage of the battery and available navigation distance were compared each other. Through some comparisons and analyses, it was cleared that the BLDC motor is more suitable for the motor of the electric propulsion system in small ships based on battery source. It is expected that the results can be used as useful data for design of the electric propulsion system with batteries.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1383-1388
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• 2010

The latest generation of tram is low-floor design, various nations in europe and japan have developed battery driven hybrid trams that combine battery and wiring. Battery driven tram system is achieved by contactless power supply system, thus system is needed high efficiency, high power and low weight traction motor for maximization of energy efficiency. Research from abroad is still in induction motor(IM) application, and it is not meet the efficiency and the power per unit volume in IPMSM. In this paper, we design compare IM and IPMSM to apply battery driven tram, and then compare these motors. To design the motor, we estimate the loading condition at first. Loading condition includes rolling resistance, air-drag resistance, and slope resistance. Based on the loading condition by estimation, we determine the power and compute rated voltage and rated current. In this paper, voltage is limited by battery voltage level. As a result, volume about IM is 1.98 times bigger than IPMSM under same condition. Even though IPMSM is bigger than IM in power density per volume, we consider more factors for actual application because there are demagnetization of permanent magnet in IPMSM and so on by external environment conditions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.8
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• pp.106-112
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• 2014

This paper presents the analysis of connected operation of photo voltaic source and Li energy storage system. The micro-grid has been installed and operated for several years at the campus of USF and has been a role of test bed. Photo voltaic source has been strongly influenced by the location, weather and climate of a installed area and Li battery is connected directly to the photo voltaic source to compensate for the limitations. The Li battery is operated to supply power output to the grid by the charging or discharging mode based on the average power output of the PV source which is calculated from monitored data for several years. The load of the PV and Li battery system is operated as a severe loading condition and the operating characteristics of PV source and Li battery are analyzed in detail. In connected operations of PV and Li battery to power system, the PV and Li battery is operated to supply constant power during only day time or peak time to increase load shedding ratio and efficient usage of generation sources in power system.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.740-746
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• 2011

Thermally activated batteries have good stability, reliability and long shelf life. Due to these characteristics and operational mechanism, thermal batteries are usually applied to military power sources. Especially, Li/$FeS_2$ thermal batteries, which are used mostly in these days, use LiCl-KCl and LiBr-LiCl-LiF as electrolytes. The electrochemistry of thermal batteries have been researched for long time, however, electrochemical study using impedance spectroscopy was not published so much. Through this research, microscopic electrochemical research was investigated with electrochemical impedance spectroscopy(E.I.S). Electrolyte effects on Li/$FeS_2$ thermal battery was researched changing electrolytes, LiCl-KCl and LiBr-LiCl-LiF. Additionally, the salts, which are added to electrolytes, effects on thermal battery were researched. It is expected that the impedance spectroscopy analysis is applicable to not only thermal battery electrochemical study effectively, but also, thermal battery developments.

• Journal of the Korean Electrochemical Society
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• v.2 no.1
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• pp.1-4
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• 1999

A lithium ion battery with polymer electrolyte is expected as a safe and long cycle life battery. This paper reports primarily the recent development results of a solid polymer electrolyte, which is a key factor of the secondary battery system, that has been obtained during the process of the development of a polymer type lithium battery. As a successful result of the solid polymer electrolyte. The ionic conductivity of the solid polymer electrolyte, which is composed of polyacrylonitrile and $LiClO_4\;with\; Al_2O_3$ dissolved as the supporting electrolyte, has been confirmed to be $2.3\times10^{-4} S/cm$ at room temperature.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.8
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• pp.1055-1061
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• 2018

Recently, due to the rapid development of electric vehicle and energy storage system, it is emphasized for battery management system to be needed and to be improved. BMS carries out various movement for optimization the use of the energy and safe use of secondary battery, these movement of BMS start at high wattage shunt fixed resistor which performs a function for detecting current among the BMS components. In addition, for the safe operation of secondary battery, the reliability of current voltage variation detected from shunt should be secured, and for corresponding characteristics, the quality of Temperature coefficient of resistance for BMS shunt and the quality of Thermo electromotive force all must be excellent. For these reasons, this study comes up with the stabilization plan for thermo electromotive force and temperature coefficient of resistance of BMS shunt resistor which is key to secondary battery operation.

• Journal of the Korean institute of surface engineering
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• v.39 no.6
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• pp.302-311
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• 2006

Nowadays the open-type lead-acid battery for vehicle use is being replaced with the sealed-type because it needs no maintenance and has a longer cycle life. Thus researches on this battery are being conducted very actively by many advanced battery companies. There is, however, a serious problem with the maintenance free(MF) battery that its cathode electrode has a limited cycle life due to a corrosion of grid. In this study, it was aimed to improve a corrosion resistance of the cathode grid which is commonly made of Pb-Ca alloy for a mechanical strength. For this purpose, various amounts of alloying elements such as Sn, Ag and Ba were added singly or together to the Pb-Ca alloys and investigated their corrosion behaviors. Batteries fabricated by using these alloys as cathode grids were subjected to life cycle test and their corrosion layers appeared at the interface between the grids and the active materials were carefully observed in order to clarify effects of alloying elements.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.6
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• pp.441-450
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• 2010

Lithium battery is widely used as the power source of various electronic devices. The formation process which is the repeated charging and discharging process is essential in the production of lithium battery. In this paper, it is proposed and designed the DC-DC converter that can charge and also discharge the lithium battery in one converter. The proposed converter is designed by considering the charge/discharge characteristics of the lithium battery. The converter is operated as a forward converter in charging process and a electrically isolated boost converter in discharging process. Based on the analyses, the number of transformer turns, inductor, capacitor, and switching devices are designed. Finally, the validity of the design for the proposed converter is verified by both simulations and experiments.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1759-1768
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• 2018

The energy density, power density and ohm resistance of battery change significantly as results of battery aging, which lead to decrease in the accuracy of the equivalent model. A parameter identification method of the equivale6nt circuit model with 3 R-C branches based on the test database of battery life cycle is proposed in this paper. This database is built on the basis of experiments such as updating of available capacity, charging and discharging tests at different rates and relaxation characteristics tests. It can realize regular update and calibration of key parameters like SOH, so as to ensure the reliability of parameters identified. Taking SOH, SOC and T as independent variables, lookup table method is adopted to set initial value for the parameter matrix. Meanwhile, in order to ensure the validity of the model, the least square method based on variable forgetting factor is adopted for optimizing to complete the identification of equivalent model parameters. By comparing the simulation data with measured data for charging and discharging experiments of Li-ion battery, the effectiveness of the full life cycle database and the model are verified.