• Journal of the Korean Society of Industry Convergence
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• v.25 no.5
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• pp.715-724
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• 2022

In many electric vehicles, large-capacity pouch-type lithium-ion battery packs are mainly used to increase the mileage on a single charge. The lithium ion battery should be operated within the temperature range of 25℃ to 40℃ because the battery performance can be rapidly deteriorated due to an increase in internal temperature. Battery thermal management system (BTMS) can give the suitable temperature conditions to battery by water cooling method. In this research, the heat transfer characteristics (the battery temperature distributions and the water flow characteristics) were analyzed by CFD method to investigate the thermal performance of the cooling plate with 4-pass water flow structure. Moreover, the effect of the presence of fins between the battery cell was identified. The fins made smooth temperature distributions between the battery cells due to the heat spreading and lower the average battery cells temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.6
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• pp.635-641
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• 2016

Regenerative braking performance of an electrically powered vehicle is closely related to driving distance per battery charge. An electric vehicle uses appropriate amounts of mechanical braking force and electromagnetic regenerative braking force to recover energy and increase driving efficiency. In particular, when it drives on a downhill road, energy recovery rate is maximized through regenerative braking during coasting based on the mass inertia of the vehicle. Since an electric two-wheeled vehicle covered in this paper is lighter than an electric four-wheeled vehicle, the improvement of its driving distance per battery charge through regenerative braking is different from an electric four-wheeled vehicle. This study compared the driving characteristics of an electric two-wheeled vehicle based on regenerative braking. Two driving test modes were simulated with a chassis dynamometer system. By analyzing the measurement of a chassis dynamometer, the driving characteristics of a two-wheel electric vehicle, such as driving efficiency, were analyzed. In addition, test results were reviewed to draw the limitations of conventional test methods for regenerative braking performance of an electric two-wheel vehicle.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1047-1048
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• 2011

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.8-13
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• 2020

In this paper, the electric vehicle (EV) and internal combustion engine vehicle (ICEV) are compared for different driving cases. The EV exhibits a lower powertrain efficiency when driven on the aggressive driving cycle than when driven on the moderate cycle. In particular, EV powertrain efficiency is low when the battery state of charge (SOC) is low, but ICEV efficiency increases when the driving cycle changes from the moderate cycle to the aggressive cycle. Based on these results, attempts can be made to increase EV powertrain efficiency. EV charging before the battery power drops to a low charging state can reduce energy consumption by 2.7% for an urban area. Furthermore, ECO driving has a more significant effect on EVs than on ICEVs.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.56-63
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• 2012

Environment has become a main issue nowadays. People began to show big interest in "futuristic means of transportation", which is an efficient method in $CO_2$ emissions reduction and decreasing use of oil. Due to the noise and emissions of two-wheel vehicle of internal combustion engine, electric two-wheeled vehicles have been supplied in downtown. The electric two-wheeled vehicles use battery as power source. The performance of lithium-ion battery changes as the ambient temperature changes. In this paper, analysis of performance variance of electric two-wheeled vehicles influenced by the temperature using the chassis dynamometer and the environmental chamber was carried out.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.10
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• pp.813-820
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• 2016

Hybrid Electric Vehicles (HEVs) are developed to be operated with two kinds of power source (Diesel Engine and Electric Motor with Rechargeable High Voltage Battery Pack). HEVs for military vehicle require high reliability to provide stable powers under serious environment such as vibration and shock. To ensure normal operation of battery pack under serious environment such as vibration and shock, the high voltage battery pack needs to have appropriate dynamic characteristics. This paper presents a design procedure for high voltage battery pack with such characteristics. An isolator design is proposed to reduce vibration and shock. Associated random vibration and shock response of the high voltage battery pack are simulated under conditions suggested by MIL specifications. Its dynamic characteristics and vibration and shock responses are validated with experiments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.6
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• pp.422-426
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• 2018

The lithium-ion battery pack of an electric vehicle (EV) deserves to be considered for an alternative use within smart-grid infrastructure. Despite the long automotive service life, EV batteries retain over 70~80% of their initial capacity. These battery packs must be managed for their reliability and safety. Therefore, a battery management system (BMS) should use specific algorithms to measure and estimate the status of the battery. Most importantly, the BMS of a grid-connected energy storage system (ESS) must ensure that the lithium-ion battery does not catch fire or explode due to an internal short from uncontrolled dendrite growth. In other words, the BMS of a lithium-ion battery pack should be capable of detecting the battery's status based on the electrochemical reaction continuously until the end of the battery's lifespan. In this paper, we propose a new protection algorithm for a dendritic lithium battery. The proposed algorithm has applied a parameter from battery pack aging results and has control power managing.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.122-130
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• 2001

In this paper, an operational algorithm for a 2-shaft parallel hybrid electric vehicle is suggested for the minimization of operation cost. The operation cost is obtained as a summation of the engine fuel cost and the motor electricity cost. The electrical cost function is estimated in case of motoring, and generating when the recuperation is carried out during the braking. In addition, weight function is introduced in order to maintain the battery state of charge. Based on the operation algorithm, the optimal engine operation point that minimizes the operation cost is obtained with respect to the required vehicle power for every state of charge of battery. The optimal operation point provides the optimal power distribution of the engine and the motor for a required vehicle power Simulation was performed and the fuel economy of the hybrid vehicle was compared to that of the conventional vehicle. Simulation results showed that hybrid vehicle's fuel economy can be improved as much as 45∼48% compared to the conventional vehicle's.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.932-939
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• 2012

This paper presents an equivalent circuit model of a LIPB (Li-Ion Polymer battery) for Hybrid Electric Vehicles (HEVs). The proposed equivalent circuit can be used to predict the charging/discharging characteristics in time domain as well as the impedance characteristic analysis in frequency domain. Based on these features, a one-cell model is established as a function of Depth of Discharge (DoD), and a 48-cell model for a battery pack was also established. It was confirmed by experiment that the proposed model predict the discharging and impedance (AC) characteristics quite accurately at different constant current levels. To check the usefulness of the proposed circuit, the model was used to simulate a motor driving circuit with an Insulated Gate Bipolar Transistor (IGBT) inverter and Brushless DC (BLDC) motor, and it is confirmed that the model can calculate the battery voltage fluctuation in time domain at different DoDs.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1714-1719
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• 2009

In this paper, methodology of battery optimal designing is proposed. Fuel cell model including dynamic characteristic is developed and load model is produced by considering driving schedule. Using these models, required energy of load and supplying energy from fuel cell are analyzed by comparing simulation results. Also parameter of fuel cell model is changed variously and battery capacity is calculated in each cases. And methode of battery optimal designing is presented by regarding dynamic characteristic of fuel cell.