• Journal of Power Electronics
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• 제14권5호
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• pp.1038-1046
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• 2014

Lithium-ion batteries are widely used in hybrid and pure electric vehicles. State-of-charge (SOC) estimation is a fundamental issue in vehicle power train control and battery management systems. This study proposes a novel model-based SOC estimation method that applies closed-loop state observer theory and a comprehensive battery model. The state-space model of lithium-ion battery is developed based on a three-order resistor-capacitor equivalent circuit model. The least square algorithm is used to identify model parameters. A multi-state closed-loop state observer is designed to predict the open-circuit voltage (OCV) of a battery based on the battery state-space model. Battery SOC can then be estimated based on the corresponding relationship between battery OCV and SOC. Finally, practical driving tests that use two types of typical driving cycle are performed to verify the proposed SOC estimation method. Test results prove that the proposed estimation method is reasonably accurate and exhibits accuracy in estimating SOC within 2% under different driving cycles.

• 한국기계가공학회지
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• 제20권4호
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• pp.57-65
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• 2021

This paper explains a DMFC-Lithium Battery hybrid system applied to a forklift. A conventional Lead Acid battery forklift has several problems: long charging times, short operation times, and frequent battery replacements. As a result, hydrogen-powered forklifts are replacing Lead acid battery-powered forklifts due to their shorter refueling time and longer operation times. However, in doing so, we are confronted with the problem of a high hydrogen refueling infrastructure. A Direct Methanol Fuel Cell (DMFC), on the other hand, is an eco-friendly generator that directly converts the chemical energy of methanol into electricity. In general, DMFC is regarded as a small power generator under kW power. In this paper, a DMFC-Battery hybrid system is applied to a 1.5 ton forklift by increasing the power output of the DMFC stack and utilizing the high charge-discharge characteristics of a lithium battery.

• 전력전자학회논문지
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• 제17권3호
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• pp.222-229
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• 2012

The SOC estimation method based on Kalman Filter(KF) requires the accurate battery model to express the electrical characteristics of the battery. However, the performance of KF SOC estimator can hardly be improved because of the nonlinear characteristic of the battery. This paper proposes the new KF SOC estimator of Lithium-Polymer Battery(LiPB), which considers the variation of parameters based on the hysteresis effect, the magnitude of SOC, the charging/discharging mode and the on/off load conditions. The proposed SOC estimation method is verified with the PSIM simulation combined the experimental data of the LiPB.

• 한국전기전자재료학회논문지
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• 제32권1호
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• pp.58-63
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• 2019

Lithium-ion batteries used for IT, automobiles, and industrial energy-storage devices have battery management systems (BMS) to protect the battery from abnormal voltage, current, and temperature environments, as well as safety devices like, current interruption device (CID), fuse, and vent to obtain positive temperature coefficient (PTC). Nonetheless, there are harmful to human health and property and damage the brand image of the manufacturer because of smoke, fire, and explosion of lithium battery packs. In this paper, we propose a systematic protection algorithm combining battery temperature, over-current, and interconnection between protection elements to prevent copper deposition, internal short circuit, and separator shrinkage due to frequent and instantaneous over-current discharges. The parameters of the proposed algorithm are suggested to utilize the experimental data in consideration of battery pack operating conditions and malicious conditions.

• 전자통신동향분석
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• 제38권5호
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• pp.90-99
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• 2023

Recently, with the trend of information technology convergence and electrification, batteries are being widely used in fields such as industry, transportation, and specific applications. By 2030, the secondary battery market is expected to grow explosively by more than eight times compared with 2020 to $351.7 billion owing to the expanding adoption of electric vehicles. Depending on the electrochemical reactions in the electrode, a primary battery can only discharge through an irreversible reaction, while a secondary battery can be repeatedly charged and discharged using reversible reactions. According to the type of charge carrier ions, secondary batteries may be classified into those made of lithium, sodium, potassium, magnesium, and aluminum ions. We analyze the current status and technological issues of lithium-ion batteries, lithium-sulfur batteries, and solid-state batteries, which are representative examples of lithium secondary batteries. In addition, research trends in lithium secondary batteries are discussed.

• KIEE International Transactions on Electrophysics and Applications
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• 제3C권5호
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• pp.189-193
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• 2003

Initial irreversible capacity (IIC) can be defined by means of the initial intercalation Ah efficiency (IIE) and the initial irreversible specific capacity at the surface (IICs) with the linear-fit range of the intercalation so as to precisely express the irreversibility of an electrode-electrolyte system. Their relationship was IIC = Qc - Q$_{D}$ = (IIE$^{-1}$ - 1) Q$_{D}$ + IICs in the linear-fit range of IIE. Here, Qc and Qd signify charge and discharge capacity, respectively, based on a complete lithium ion battery cell. Charge indicates lithium insertion to carbon anode. Two terms of IIE and IICs depended on the types of active materials and compositions of the electrode and electrolyte but did not change with charging state. In an ideal electrode-electrolyte system, IIE and IICs would be 100%, 0 mAh/g for the electrode and mAh for the cell, respectively. These properties can be easily obtained by the Gradual Increasing of State of Charge (GISOC).OC).

• Journal of Power Electronics
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• 제19권4호
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• pp.858-868
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• 2019

With the widespread use of modern clean energy, lithium-ion batteries have become essential as a more reliable energy storage component in the energy Internet. However, due to the difference in monomers, some of the battery over-charge or over-discharge in battery packs restrict their use. Therefore, a novel multiphase interleaved converter for reducing the inconsistencies of the individual cells in a battery pack is proposed in this paper. Based on the multiphase converter branches connected to each lithium battery, this circuit realizes energy transferred from any cell(s) to any other cell(s) complementarily. This flexible interlaced converter is composed of an improved bi-directional Buck-Boost circuit that is presented with its own available control method. A simulation model based on the PNGV model of fundamental equalization is built with four cells in PSIM. Simulation and experimental results demonstrate that converter and its control achieve simple and fast equalization. Furthermore, a comparison of traditional methods and the HNFABC equalization is provided to show the performance of the converter and the control of lithium-based battery stacks.

• Carbon letters
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• 제1권1호
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• pp.36-40
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• 2000

The initial irreversible capacity (IIC) of a hard carbon during the charge/discharge reaction is strongly affected by both the initial irreversible capacity on the carbon surface $(IIC_S)$ and the initial irreversible lithium insertion into carbon $(IIC_B)$. The initial coulombic efficiency of the insertion and the desertion of lithium (IIE) can be used as a performance to classify $IIC_B$ of the carbon. The $IIC_B$ was proportional to the specific discharge capacity with a slope, $IIE^{-1}$ - 1. The IIE of hard carbon had four regions. $IIE_A$ for the region of 0~95 mAh/g of $Q_{D1}$ was 60.2%. $IIE_B$ and $IIE_C$ for the regions of 95~172 mAh/g and 172~308 mAh/g had 84.9% and 91.5%, respectively. $IIE_D$ was appeared above 308 mAh/g. But, the $IIE_D$ was reduced to 82.1% compared with $IIE_C$. These IIE might be corresponding to lithium desertion from carbon at the region of 0~172 mAh/g range, lithium desertion from the micropore of carbon at the region of 172~308 mAh/g range, and to the lithium stripping of the plated lithium for the region above 308 mAh/g, respectively.

• 멤브레인
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• 제27권1호
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• pp.92-103
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• 2017

본 연구에서는 리튬이온전지용 친수화된 세퍼레이터의 전기화학적 성능에 대한 연구를 진행하였다. 리튬이온전지용 분리막으로 사용되는 폴리올레핀 소재는 소수성이고, 카보네이트 계열의 유기용매를 사용하는 전해액은 친수성을 가진다. 따라서 리튬이온전지는 수계전해액을 사용하기 때문에 폴리올레핀계 분리막에 다양한 친수성 고분자를 도입하여 친수화 처리하였다. 코팅된 세퍼레이터의 변화를 평가하기 위해, 표면 관찰, 코팅시간에 따른 친수화도, 다공성, 젖음성에 대한 특성평가를 수행하였다. 최종적으로 리튬이온이 코팅된 세퍼레이터의 저항과., 이온전도도를 측정하여 리튬이온전지 성능평가를 진행하였다. PMVE로 코팅한 세퍼레이터의 친수화 정도가 우수하며, 세퍼레이터의 기공이 잘 유지되어 우수한 이온전도도를 나타냄으로써 이차전지 배터리에 적용을 위한 잠재성을 가짐을 확인하였다.

• 전기학회논문지
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• 제65권6호
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• pp.962-968
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• 2016

The large scaled lead-acid battery is widely used for efficient operation of the photovoltaic system in many islands. However, lithium-ion battery is now being introduced to mitigate the fluctuation of wind power and to replace lead-acid battery. Therefore, hybrid ESS(Energy Storage system) that combines lithium-ion battery with lead-acid battery is being required because lithium-ion battery is costly in present stage. Under this circumstance, this paper presents the optimal algorithm to create composition rate of hybrid ESS by considering fixed and variable costs in order to maximize advantage of each battery. With minimization of total cost including fixed and variable costs, the optimal composition rate can be calculated based on the various scenarios such as load variation, life cycle and cost trend. From simulation results, it is confirmed that the proposed algorithms are an effective tool to produce a optimal composition rate.