• Journal of Power Electronics
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• v.16 no.6
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• pp.2035-2044
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• 2016

In order to match the voltages between high voltage battery stacks and low voltage super-capacitors with a high conversion efficiency in hybrid energy sources electric vehicles (HESEVs), a high ratio bidirectional DC-DC converter with a synchronous rectification H-Bridge is proposed in this paper. The principles of high ratio step-down and step-up operations are analyzed. In terms of the bidirectional characteristic of the H-Bridge, the bidirectional synchronous rectification (SR) operation is presented without any extra hardware. Then the SR power switches can achieve zero voltage switching (ZVS) turn-on and turn-off during dead time, and the power conversion efficiency is improved compared to that of the diode rectification (DR) operation, as well as the utilization of power switches. Experimental results show that the proposed converter can operate bidirectionally in the wide ratio range of 3~10, when the low voltage continuously varies between 15V and 50V. The maximum efficiencies are 94.1% in the Buck mode, and 93.6% in the Boost mode. In addition, the corresponding largest efficiency variations between SR and DR operations are 4.8% and 3.4%. This converter is suitable for use as a power interface between the battery stacks and super-capacitors in HESEVs.

• Fire Science and Engineering
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• v.33 no.1
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• pp.23-29
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• 2019

Rechargeable battery such as lithium-ion battery has been noticed as a kinds of the energy storage system in the recent energy utilization and widely used actually in various small electronic equipment and electric vehicles. However, many thermal runaway caused battery accidents occurred recently, which still is obstacle for advanced application of lithium ion battery. One of the main differences to general fires is the existence of ionized electrolyte with electron during combustion. Therefore, we simply simulated the ion addition effects of battery fires by introducing an ionized fuel in jet diffusion flames. When the ionized methane through a corona discharge was used as fuel, the overall flame stability and shape such as flame length showed no significant difference from normal methane flame, but NOx and CO emissions measured at the post flame region decreased. The ion addition effect of methane oxidation was also numerically simulated with the modeling of hydrogen addition in the mixture. It was confirmed that the hydrogen addition at a fixed temperature had a similar effects on ionization of methane and hence could be modeled successfully.

• The Journal of Korean Institute for Practical Engineering Education
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• v.4 no.2
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• pp.129-135
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• 2012

There are many ways in which electric vehicles are mathematically modeled and simulated. The components have different physical background and models, but have to fit into one mathematical model. A multiphysics model structure is required. Depending on the goal of the simulation, there are various levels on which the simulation can be performed. This is called multilevel, consisting of a conceptual system level, a circuit level and a more detailed component level. This paper discusses which multiphysics models and multilevel simulations are required for the various components in an electric vehicle. Also, this simulation approach could improve the effectiveness of learning in engineering education.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5899-5905
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• 2014

Faults in electric power system can be a critical problem for vehicles. The system durability is determined mainly by the durability of their components and operating conditions. Monitoring the conditions of the electric power system may be necessary because it is very difficult to predict precisely when it will fail. Therefore, the aim of this study was to develop a diagnosis system for an electric power system of a vehicle. The alternator voltage, excitation voltage, lamp voltage, battery voltage, and engine rpm from a crank angle sensor are monitored continuously and the system fault can be then detected in real time. NI USB- 9201 DAQ and LabVIEW SW have been used to measure the voltages and analyze the data. Compared to conventional measurements for only each component, an integrated and portable measurement method was developed. In addition to the monitoring the electric power system in real time, the saved data from the measurement also provides valuable information to improve the durability of the components.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.3
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• pp.91-106
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• 2019

The demand for lithium has increased sharply due to the explosive increase in lithium secondary batteries for environment-friendly vehicles (EV: Electric Vehicle, HEV: Hybrid Electric Vehicle, PHEV: Plug-in Hybrid Electric Vehicle). Traditionally, lithium has been produced mainly from lithium-containing minerals and brine, and recently it also has been recovered along with other valuable metals by recycling cathode materials of lithium secondary batteries. In this study, we comprehensively reviewed various recovering precesses of lithium from lithium-containing substances.

• The Journal of the Acoustical Society of Korea
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• v.41 no.6
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• pp.669-679
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• 2022

Lithium-ion battery has been used for lots of electronic devices. With the popularization of batteries, researchers have focused on batteries' electrochemical performances by environmental conditions, such as temperature, vibration, shock and charging state. Meanwhile, due to very serious global warming, car companies have started using lithium-ion batteries even in cars, replacing internal combustion engines. However, batteries have been developed based on non-moving systems which is totally different from vehicles. In the line of the differences, researchers have tried to reveal relationship between variables from dynamic systems and batteries. In this review, we discuss the comprehensive effect of vibration and shock on batteries. We firstly summarize vibration profiles and effect of normal vibration on batteries. We also sum up effect of shock and penetration on batteries and introduce how ultrasound influences on batteries. Lastly, outlook for the battery design as well as dynamic design of EVs are discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.74-83
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• 2009

Recently, usage of electric and electronic system for car increases rapidly. Consequently power monitoring supplied to the system is essential for management and controlling. Generally, battery status is monitored through measuring and diagnosing the current measurement method utilizing Hall Effect. Therefore, in this paper, we analysed magnetic field to develop the solution of DC current sensor using Hall Effect which is the core of design and development. By analysing the magnetic field by FEM using Maxwell 3D software, the location of the highest output current and stable part in the Hall IC sensor was shown. Also, the optimal core design of DC current sensor using parametric and Simplex method was presented. A car battery charge and discharge process dependant on time effect on the changing of magnetic field was simulated and compared to the result from the experiment result of actual vehicle.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.70-72
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• 2019

For the safe and reliable operation of Lithium-ion batteries in Electric Vehicles (EVs) or Energy Storage Systems (ESSs), it is essential to have accurate information of the battery such as State of Charge (SOC). Many kinds of different techniques to estimate the SOC of the batteries have been developed so far such as the Kalman Filter. However, when it is applied to the multiple number of batteries it is difficult to maintain the accuracy of the estimation over all cells due to the difference in parameter value of each cell. Moreover the difference in the parameter of each cell may become larger as the operation time accumulates due to aging. In this paper a novel Deep Neural Network (DNN) based SOC estimation method for multi cell application is proposed. In the proposed method DNN is implemented to learn non-linear relationship of the voltage and current of the lithium-ion battery at different SOCs and different temperatures. In the training the voltage and current data of the Lithium battery at charge and discharge cycles obtained at different temperatures are used. After the comprehensive training with the data obtained with a cell resulting estimation algorithm is applied to the other cells. The experimental results show that the Mean Absolute Error (MAE) of the estimation is 0.56% at 25℃, and 3.16% at 60℃ with the proposed SOC estimation algorithm.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.5
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• pp.376-379
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• 2021

The design and performance of a SiC-MOSFET-based 11-kW bi-directional on-board charger (OBC) for electric vehicles is presented. The OBC consists of a three-phase two-level AC/DC converter and a CLLLC resonant converter. All the power devices are implemented with SiC-MOSFETs to reduce the conduction losses generated in the OBC, and the DC-link voltage is designed to track the level of battery voltage in the forward and reverse powering modes. As a result, the CLLLC resonant converter always runs at the switching frequency near the resonant frequency, resulting in high-efficiency operation at the maximum powering modes. As the DC-link voltage varies according to the battery voltage, the AC/DC converter in the proposed OBC adopts an adaptive DC-link voltage controller. The performance of the proposed 11-kW OBC is verified by a prototype converter with the following specifications: three-phase 60-Hz 380-V input, 11-kW capacity, and battery voltage range of 214-413-V, resulting in the conversion efficiency of over 95.0-% in the forward and reverse powering modes.

• Corrosion Science and Technology
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• v.22 no.4
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• pp.287-296
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• 2023

Li-ion batteries have been gaining increasing importance, driven by the growing utilization of renewable energy and the expansion of electric vehicles. To meet market demands, it is essential to ensure high energy density and battery safety. All-solid-state batteries (ASSBs) have attracted significant attention as a potential solution. Among the advantages, they operate with an ion-conductive solid electrolyte instead of a liquid electrolyte therefore significantly reducing the risk of fire. In addition, by using high-capacity alternative electrode materials, ASSBs offer a promising opportunity to enhance energy density, making them highly desirable in the automotive and secondary battery industries. In ASSBs, Li metal can be used as the anode, providing a high theoretical capacity (3860 mAh/g). However, challenges related to the high interfacial resistance between Li metal and solid electrolytes and those concerning material degradation during charge-discharge cycles need to be addressed for the successful commercialization of ASSBs. This review introduces and discusses the interfacial reactions between Li metal and solid electrolytes, along with research cases aiming to improve these interactions. Additionally, future development directions in this field are explored.