• 한국수소및신에너지학회논문집
• /
• 제31권5호
• /
• pp.489-497
• /
• 2020

The Li-ion battery is considered to be one of the potential power sources for electric vehicles. In fact, the efficiency, reliability, and cycle life of Li-ion batteries are highly influenced by their thermal conditions. Therefore, a novel thermal management system is highly required to simultaneously achieve high performance and long life of the battery pack. Basically, thermal modeling is a key issue for the novel thermal management of Li-ion battery systems. In this paper, as a basic study for battery thermal modeling, temperature distributions inside the simple Li-ion battery pack (comprises of nine 18650 Li-ion batteries) under a 1C discharging condition were investigated using measurement and computational fluid dynamics (CFD) simulation approaches. The heat flux boundary conditions of battery cells for the CFD thermal analysis of battery pack were provided by the measurement of single battery cell temperature. The temperature distribution inside the battery pack were compared at six monitoring locations. Results show that the accurate estimation of heat flux at the surface of single cylindrical battery is paramount to the prediction of temperature distributions inside the Li-ion battery under various discharging conditions (C-rates). It is considered that the research approach for the estimation of temperature distribution used in this study can be used as a basic tool to understand the thermal behavior of Li-ion battery pack for the construction of effective battery thermal management systems.

• 반도체디스플레이기술학회지
• /
• 제13권1호
• /
• pp.101-108
• /
• 2014

The battery pack in this research consists of dozens of a small battery for energy storage. And this battery pack charges and discharges repeatedly at high capacity (25 ~ 50 V, 25 ~ 100 A). The high temperature which can be generated in this process has a bad effect to the lifetime and efficiency of batteries. Moreover these factors are related with maintenance cost. Therefore, we need to assess the thermal performance of the battery pack in advance using the experimental or numerical analysis. In this research, we analyzed voltage and surface temperature of one cell battery to calculate heat transfer using the numerical analysis. And the temperature of the battery surfaces and inside of the pack was also analyzed. As a result, we found out the appropriate pack structure which stacked five modules.

• 반도체디스플레이기술학회지
• /
• 제14권1호
• /
• pp.39-43
• /
• 2015

This paper is to derive information about the optimal shape of the pack has a minimum temperature range of a Li-ion battery equipped with a module. We selected the shape of the pack in order to reduce the temperature deviation between the batteries as a variable. And we derived the experimental points with a minimum of DOE by D-optimal. We analyzed the temperature and the flow within the battery pack by using a numerical analysis verified in previous studies. We derive the equation for the temperature variation in the objective function using the RSM and performed optimization. As a result, it was confirmed that with the variation in the $1.706e-4^{\circ}C$ when to apply an optimized shape.

• 한국기계가공학회지
• /
• 제8권2호
• /
• pp.90-95
• /
• 2009

This paper presents a new lithium ion unit-cell and pack battery by using a new formulation ratio of material. The three types of formulation ratio for the unit-cell were used. The life cycle and basic properties of the lithium ion unit-cell$({\Psi}18{\times}65(mm))$ about one of them were acquired by the charge-discharge experiment. The nominal voltage, nominal capacity and cycle life output of the lithium ion unit-cell is respectively 3.7V, 2.4Ah, and above 500cycle. Pack type lithium ion battery has the size of $29.5{\times}73.5{\times}115(mm)$ and the weight of 300g. As the results, the weight and bulk of lithium ion battery used to a safety lamp were decreased to 1/4 and 1/7. In addition, the comparison of the new lithium ion battery and lead storge battery for confirming the effectiveness of the new lithium ion battery have been performed.

• 반도체디스플레이기술학회지
• /
• 제15권2호
• /
• pp.20-25
• /
• 2016

The parallel computer cluster system has been known as the powerful tool to solve a complex physical phenomenon numerically. The numerical analysis of large size of Li-ion battery pack, which has a complex physical phenomenon, requires a large amount of computing time. In this study, the numerical analyses were conducted for comparing the computing efficiency between the single workstation and the parallel cluster system both with multicore CPUs'. The result shows that the parallel cluster system took the time 80 times faster than the single work station for the same battery pack model. The performance of cluster system was increased linearly with more CPU cores being increased.

• Journal of Power Electronics
• /
• 제18권4호
• /
• pp.1127-1139
• /
• 2018

A reduced particle-unscented Kalman filter estimation method, along with a splice-equivalent circuit model, is proposed for the state-of-charge estimation of an aeronautical lithium-ion battery pack. The linearization treatment is not required in this method and only a few sigma data points are used, which reduce the computational requirement of state-of-charge estimation. This method also improves the estimation covariance properties by introducing the equilibrium parameter state of balance for the aeronautical lithium-ion battery pack. In addition, the estimation performance is validated by the experimental results. The proposed state-of-charge estimation method exhibits a root-mean-square error value of 1.42% and a mean error value of 4.96%. This method is insensitive to the parameter variation of the splice-equivalent circuit model, and thus, it plays an important role in the popularization and application of the aeronautical lithium-ion battery pack.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2013년도 추계학술대회 논문집
• /
• pp.200-201
• /
• 2013

This paper investigates a new approach for Li-Ion battery state-of-charge (SOC) estimation using sliding mode observer (SMO) technique including parameters aging compensation via recursive least squares (RLS). The main advantages of this approach would be low computational load, easiness of implementation along with the robustness of the method for internal battery model parameters estimation. The proposed algorithm was first tested on a set of acquired battery data using implementation in Simulink and later developed as C-code module for firmware application.

• 한국수소및신에너지학회논문집
• /
• 제31권6호
• /
• pp.622-629
• /
• 2020

The performance and cost of electric vehicles (EVs) are much influenced by the performance and service life of the Li-ion battery system. In particular, the cell performance and reliability of Li-ion battery packs are highly dependent on their operating temperature. Therefore, a novel battery thermal management is crucial for Li-ion batteries owing to heat dissipation effects on their performance. Among various types of battery thermal management systems (BTMS'), the phase change material (PCM) based BTMS is considered to be a promising cooling system in terms of guaranteeing the performance and reliability of Li-ion batteries. This work is mainly concerned with the basic research on PCM based BTMS. In this paper, a basic experimental study on PCM based battery cooling system was performed. The main purpose of the present study is to present a comparison of two PCM-based cooling systems (n-Eicosane and n-Docosane) of the unit 18650 battery module. To this end, the simplified PCM-based Li-ion battery module with two 18650 batteries was designed and fabricated. The thermal behavior (such as temperature rise of the battery pack) with various discharge rates (c-rate) was mainly investigated and compared for two types of battery systems employing PCM-based cooling. It is considered that the results obtained from this study provide good fundamental data on screening the appropriate PCMs for future research on PCM based BTMS for EV applications.

• 전기전자학회논문지
• /
• 제23권1호
• /
• pp.1-8
• /
• 2019

본 논문에서는 18650 원통형 NCA 리튬이온 배터리로 구성된 고출력 직렬 배터리로 다양한 C-rate의 전기적 특성을 테스트한다. 테스트를 통해 추출한 14S1P 배터리 팩의 방전 용량 데이터와 4S1P 배터리 팩의 EV cycle 데이터를 통해 C-rate의 변화에 따른 전기적 특성을 분석한다. 분석을 통해 얻은 데이터를 기반으로 C-rate에 따른 방전용량 실험의 셀 간 전압 편차와 EV cycle 실험의 셀 간 전압 편차를 다중선형회귀 모델로 추정하여 선형적인 특징을 가진 데이터와 비선형적인 특징을 가진 데이터에 대한 각각의 추정성능을 검증한다. 모델의 추정성능을 검증하기 위해 추정 데이터와 실제 데이터의 RMSE를 구해 알고리즘의 정확성을 평가한다. 논문의 결과는 14S1P 배터리 팩의 방전 용량의 셀 간 전압 불균형과 4S1P 배터리 팩의 EV cycle의 셀 간 전압 불균형 중 선형적인 데이터인 방전 용량의 셀 간 불균형 데이터의 추정 성능이 더 뛰어난 것을 검증하는데 기여한다.

• 전기전자학회논문지
• /
• 제15권4호
• /
• pp.324-329
• /
• 2011

휴대 기기가 고기능화, 다기능화 됨에 따라 다양한 멀티미디어 기능이 요구되면서 배터리를 보다 장시간 이용하면서 더 높은 전력과 에너지가 요구되고 있다. 이에 따라 여러 개의 리튬이온 cell을 연결한 배터리팩이 많이 사용되고 있다. 2개 이상의 cell로 구성된 리튬이온 배터리를 안전하게 사용하기 위해서는 과전압 및 과전류, 고온으로 부터 보호해야 됨은 물론, 수명을 연장하기 위해서 각 cell의 전압을 같게 유지시켜주는 balancing 기능이 반드시 요구된다. 본 논문에서 제안한 IC는 모바일 기기뿐만 아니라 E-bike, 하이브리드 자동차, 전기 자동차 분야에도 적용 가능할 것으로 예상되며, 국내 PMIC 발전에 기여할 것으로 기대된다.