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1.
庞辉 《物理学报》2017,66(23):238801-238801
锂离子电池的精确建模和状态估计对于电动汽车电池管理系统非常重要,准二维(P2D)电化学模型由于计算复杂,难以直接应用于电池管理的参数在线估计和实时控制中.本文基于多孔电极理论和浓度理论,提出一种考虑锂离子液相动力学的简化准二维(SP2D)模型.忽略锂离子孔壁流量沿电极厚度方向的变化求解SP2D模型所描述的锂离子电池锂浓度分布,基于锂离子电池电化学平均动力学行为求解固相和液相电势变化,推导出电池电压计算的简化表达式;采用恒流、脉冲以及城市循环工况放电电流对比分析了严格P2D模型与SP2D模型的终端电压和浓度分布.结果表明:SP2D模型在保持较高计算精度的同时,可显著提高计算效率.  相似文献   

2.
刘征宇  杨昆  魏自红  姚利阳 《物理学报》2019,68(9):98801-098801
锂离子电池的电化学模型对于电池特性分析和电池管理具有重要意义,但是准二维(P2D)模型复杂度太高,为了在保证模型精度的基础上尽量降低复杂度,本文提出了一种包含液相简化的P2D (LSP2D)模型,该模型首先基于电化学平均动力学将电池端电压化简成为仅耦合固相Li+浓度c_s和液相Li+浓度c_e的方程,然后进一步对表达c_s和c_e演化规律的偏微分方程进行抛物线近似化简,使得最终的模型由多项式组成.COMSOL仿真表明在放电倍率为1C时该模型与单粒子(SP)模型的估算精度和速度相当,但在放电倍率为3C时,该模型的估算时间比P2D模型减少了99.73%,与SP模型相当,估算精度相比SP模型有大幅度提升.  相似文献   

3.
汤依伟  贾明  程昀  张凯  张红亮  李劼 《物理学报》2013,62(15):158201-158201
基于电化学-热耦合模型研究聚合物锂离子动力电池放电过程热行为, 分析了放电倍率、冷却条件对电池放电过程的温度变化及分布的影响规律. 结果表明: 3C放电时, 模型计算结果与实测结果的平均偏差为0.57 K, 方差为0.15, 说明模型准确度较高. 电芯的平均生热率在整个放电过程中呈现出增加的趋势, 初期和末期增长较快. 大倍率放电时, 与电流密度的平方呈正比的不可逆热所占的比重较大, 小倍率放电时, 电化学反应可逆热占主导. 改善冷却条件能降低电池放电过程的平均温度, 对流传热过程的表面传热系数为5 W/(m2·K), 1 C, 3 C, 5 C放电结束时, 电芯的平均温升为分别为6.46 K, 17.67 K, 27.53 K, 当对流传热过程的表面传热系数增加至25 W/(m2·K)时, 温升比自然对流条件下相同倍率放电时的温度分别降低了2.91 K, 4.68 K, 5.62 K, 但电芯温度分布的不一致性也会加剧. 关键词: 电化学 耦合 锂离子动力电池 温度分布  相似文献   

4.
庞辉 《物理学报》2018,67(5):58201-058201
为了精确识别电动汽车锂离子动力电池的关键状态参数,基于多孔电极理论和浓度理论,建立了一种考虑液相动力学行为的锂离子电池扩展单粒子模型.相较于传统单粒子模型,该模型增加了对负电极表面固体电解质界面膜参数的描述,并考虑了温度和液相浓度变化对锂离子电池关键参数的耦合影响.基于所建立的扩展单粒子模型,提出一种简化的参数灵敏度分析方法和有效的锂电池参数识别策略,用以确定特定工况下的高灵敏度待识别参数,进而利用遗传算法实现参数的优化求解.最后,通过对比分析本文模型和传统单粒子模型的仿真输出电压和相同工况下电池的实验输出电压验证了提出模型和参数识别方法的有效性和可行性,为电池管理系统的健康状态估计提供了理论基础.  相似文献   

5.
电解液中的锂离子浓度表达是锂离子电池电化学模型求解的基本任务之一.为了平衡单粒子模型的液相动态性能和计算效率,假设反应仅发生在集电极和电解质界面上,为此,提出一种基于液相扩散方程无穷级数解析解的界面浓度求解新方法.在恒流工况下,利用数列单调收敛准则将解析解转化为一个收敛和函数.在动态工况下,将该解析解简化为输入与和函数的无限离散卷积.利用和函数随时间单调衰减并收敛至零的特性对其进行截断,从而得到有限离散卷积求解算法.对比专业有限元分析软件,该方法在恒流工况和动态工况下均能以较少的计算时间获得相当好的精度.而且,该方法仅有一个配置参数.因此,所提方法将有效减小应用于实时电池管理系统上的电化学模型计算负担.  相似文献   

6.
电解液中的锂离子浓度表达是锂离子电池电化学模型求解的基本任务之一.为了平衡单粒子模型的液相动态性能和计算效率,假设反应仅发生在集电极和电解质界面上,为此,提出一种基于液相扩散方程无穷级数解析解的界面浓度求解新方法.在恒流工况下,利用数列单调收敛准则将解析解转化为一个收敛和函数.在动态工况下,将该解析解简化为输入与和函数的无限离散卷积.利用和函数随时间单调衰减并收敛至零的特性对其进行截断,从而得到有限离散卷积求解算法.对比专业有限元分析软件,该方法在恒流工况和动态工况下均能以较少的计算时间获得相当好的精度.而且,该方法仅有一个配置参数.因此,所提方法将有效减小应用于实时电池管理系统上的电化学模型计算负担.  相似文献   

7.
锂离子电池多尺度数值模型的应用现状及发展前景   总被引:1,自引:0,他引:1       下载免费PDF全文
程昀  李劼  贾明  汤依伟  杜双龙  艾立华  殷宝华  艾亮 《物理学报》2015,64(21):210202-210202
锂离子电池是一种较为复杂的电化学系统, 其涵盖质量传递、电荷传递、热量传递以及多种电化学反应等物理化学过程. 其不仅物理尺度跨越大, 从微观活性颗粒、极片、电芯跨越到电池模组, 还面临着成组配对以及均衡性的问题, 这些问题加剧了电池设计和性能综合评估的难度. 通过计算机数值仿真技术, 建立数学模型, 全面和系统地捕捉电池工作过程各物理场的相互作用机理, 分析其演化规律, 能够为优化电池系统设计提供理论支撑. 本文对锂离子电池的数值模型研究进展和发展趋势进行了综述. 同时对主要理论模型进行了分类整理, 总结了它们的特点、适用范围和局限性, 指出了将来进一步研究的方向和难点所在, 这些对锂离子电池多尺度数值模型的理论研究和工程应用都具有指导性的意义.  相似文献   

8.
锂离子动力电池经过多次充放电循环后,不可避免出现老化现象,单体电池局部温差增大,成组效应更加明显.本文建立了非均匀产热动力电池组三维模型,采用数值模拟的方法,模拟分析了基于相变材料的圆柱形LiFePO_4动力电池模块(4×6)的降温与均温性能。结果表明,相比没有填充PCM情况,填充PCM后,最高温度随时间呈现先明显增加后逐渐平缓的趋势,放电结束时明显降低,但随着导热系数的增加,最高温度降低不明显。在单体电池固有较大温差情况下,采用StyleⅠ方式排列电池正负极,降低相变温度和增加导热系数均难很好地控制电池模块温度均匀性。对于正负极出现产热不均匀的老化电池组,采用styleⅡ或styleⅢ排列方式是必要的。  相似文献   

9.
隔膜孔隙结构对锂离子电池性能具有重要的影响,本文提出了可准确描述充放电过程中锂离子电池内部复杂物理化学现象的电化学-热耦合模型,发现该模型较文献中模型的计算结果更接近实验测试数据.利用该模型探讨了隔膜孔隙率与扭曲率分别对锂离子电池性能的影响规律,发现减小孔隙率或增大扭曲率,电池输出电压、最大放电容量和平均输出功率均不断降低,电池表面温度和温升速度均不断升高;当孔隙率减小或扭曲率增大到一定程度时,放电初期电池输出电压均会出现先下降后回升的现象,且孔隙率越小或扭曲率越大,其下降的幅度越大、速度越快,回升所需时间也越长;要确保其不低于截止电压,隔膜扭曲率必须小于临界扭曲率(其下降至最低点刚好等于截止电压时的隔膜扭曲率).综合分析了放电过程中电池内部各电化学参量和产热量的动态分布规律,发现隔膜孔隙率和扭曲率主要影响放电末期电极膜片内部电化学反应以及其他放电时刻电解液中有效Li~+扩散(传导)系数.  相似文献   

10.
本文提出一个针对直接甲醇燃料电池膜及阴极的二维、多组分稳态数学模型.模型根据直接甲醇膜燃料电池膜及阴极运行工况特性,考虑质量、动量、组分守恒以及电池中的电化学过程而建立,并应用了计算流体动力学(CFD)技术.模拟结果表明传质对直接甲醇燃料电池的性能影响很大;本文还进行了直接甲醇燃料电池阴极水管理的初步探讨.  相似文献   

11.
Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.  相似文献   

12.
A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.  相似文献   

13.
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.  相似文献   

14.
A multi-conjugate adaptive optics (MCAO) can offer a possibility of widening field of view (FOV) characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle's expressions of two deformable mirrors (DMs) MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.  相似文献   

15.
Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.  相似文献   

16.
17.
The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.  相似文献   

18.
19.
40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.  相似文献   

20.
Characterization of PolyA and PolyC mismatches by Raman spectroscopy   总被引:1,自引:0,他引:1  
A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.  相似文献   

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