A comparative study of data-driven battery capacity estimation based on partial charging curves

With its generality and practicality, the combination of partial charging curves and machine learning(ML) for battery capacity estimation has attracted widespread attention. However, a clear classification,fair comparison, and performance rationalization of these methods are lacking, due to the scattered existing studies. To address these issues, we develop 20 capacity estimation methods from three perspectives:charging sequence construction, input forms, and ML models. 22,582 charging curves are generated from 44 cells with different battery chemistry and operating conditions to validate the performance. Through comprehensive and unbiased comparison, the long short-term memory(LSTM) based neural network exhibits the best accuracy and robustness. Across all 6503 tested samples, the mean absolute percentage error(MAPE) for capacity estimation using LSTM is 0.61%, with a maximum error of only 3.94%. Even with the addition of 3 m V voltage noise or the extension of sampling intervals to 60 s, the average MAPE remains below 2%. Furthermore, the charging sequences are provided with physical explanations related to battery degradation to enhance confidence in their application. Recommendations for using other competitive methods are also presented. This work provides valuable insights and guidance for estimating battery capacity based on partial charging curves.

Simulation of Space Charge Impact on Partial Discharge Inception Voltage in Power Busbars Dedicated to Future Hybrid Aircrafts

Reducing greenhouse gases, saving energy resources and mass optimization require technological changes towards increasingly electric vehicles. At the same time, performance improvement of semiconductor and dielectric materials further promotes electronic components confinement, resulting in a significant increase of embedded power densities. In the particular case of future hybrid propulsion aircrafts, electrical power that intended to supply reactors would be converted through power electronics components mounted on power busbars and insulated by solid dielectrics materials. These dielectrics materials have to respond to various electrical constraints of use (HVDC), in spite of environment change of aircraft parameters such as low pressure, temperature and thermal cycles, humidity... Unfortunately, partial discharges phenomenon is the most problem within electrical insulation system (EIS). Based on a topological model of power busbars designed for power converters dedicated to hybrid aircraft, partial discharge studies were conducted by simulation in various charging conditions of a PTFE insulator. Simulation results, which focus on electric field thresholds criteria of partial discharge inception voltage in air, reveal a net sensitivity of a space charge accumulation and distribution on dielectrics behaviour even for low space charge density, depending on their location in dielectrics. Compared to the behaviour observed with implanted homocharges, when by increasing homocharges density from 0.5 C/m3 to 2 C/m3 we observe a decrease of electric field by 450%, simulation results show a highest risk of partial discharge inception when heterocharges are accumulated inside dielectrics. Their accumulation increases the electric field in triple points beyond electric field thresholds of partial discharge inception in air. The simulated electric field reaching 22 kV/mm with only 2 C/m3 of heterocharges density accumulated in dielectric/busbars interfaces.

Estimation of pulsed laser-induced single event transient in a partially depleted silicon-on-insulator 0.18-μm MOSFET

In this paper, we investigate the single event transient （SET） occurring in partially depleted silicon-on-insulator （PDSOI） metal-oxide-semiconductor （MOS） devices irradiated by pulsed laser beams. Transient signal characteristics of a 0.18-p.m single MOS device, such as SET pulse width, pulse maximum, and collected charge, are measured and an- alyzed at wafer level. We analyze in detail the influences of supply voltage and pulse energy on the SET characteristics of the device under test （DUT）. The dependences of SET characteristics on drain-induced barrier lowering （DIBL） and the parasitic bipolar junction transistor （PBJT） are also discussed. These results provide a guide for radiation-hardened deep sub-micrometer PDSOI technology for space electronics applications.

A Computational Evaluation of Bond Order and Charge Distributions in Isomeric Aminotroponiminiums and Their Benzo-Fused Derivatives

This paper reports the results on the nature of bond-order and net charge distributions predicted by Ab initio Hartree- Fock procedures for 1-amino-2-iminio-, 1-amino-3-iminio- and 1-amino-4-iminiotropylium cations that incorporate, in order, the 1,7-, 1,3- and 1,5-diazapentadienium (vinamidinium) elements. There appears to be very little contribution from tropylium-type charge distribution, the positive charges residing largely in the nitrogen atoms. The partial bond fixations and charge distributions show interesting variation in the three isomers. The 1,3-isomer in which the 1,3-diazapentadienium element is preserved in the favoured zigzag conformation appears to be relatively the best stabilized. The six isomeric benzo-fused derivatives arising from the three amino-iminiotropylium cations show similar differences in patterns of behaviour. Interestingly, the isomer in which a zigzag 1,3-diazapentadienium element is conjugated with a styrene moiety receives the deepest stabilization. While showing that the element largely contributes to the relative stabilization among the systems studied, contribution from certain stereochemical destabilizing factors may not be insignificant.

A new structure and its analytical model for the vertical interface electric field of a partial-SOI high voltage device

A new partial-SOI （PSOI） high voltage device structure called a CI PSOI （charge island PSOI） is proposed for the first time in this paper. The device is characterized by a charge island layer on the interface of the top silicon layer and the dielectric buried layer in which a series of equidistant high concentration n＋-regions is inserted. Inversion holes resulting from the vertical electric field are located in the spacing between two neighbouring n＋-regions on the interface by the force with ionized donors in the undepleted n＋-regions, and therefore effectively enhance the electric field of the dielectric buried layer （Ei） and increase the breakdown voltage （BV）, thereby alleviating the self-heating effect （SHE） by the silicon window under the source. An analytical model of the vertical interface electric field for the CI PSOI is presented and the analytical results are in good agreement with the 2D simulation results. The BV and El of the CI PSOI LDMOS increase to 631 V and 584 V/μm from 246 V and 85.8 V/μm for the conventional PSOI with a lower SHE, respectively. The effects of the structure parameters on the device characteristics are analysed for the proposed device in detail.

The direct ionization processes in the collisions of partially stripped carbon and oxygen ions with helium atoms at low-to-intermediate energies

The values of direct double- to-single ionization ratio R of helium atoms induced by C^q＋, O^q＋ （q = 1 -4） ions at incident energies from 0.2 to 8.5MeV are measured. Based on the existing model （Shao J X, Chen X M and Ding B W 2007 Phys. Rev. A 75 012701） the effective charge of the projectile is introduced to theoretically estimate the value of R for the partially stripped ions impacting on helium atoms. The results calculated from our ＂effective charge＂ model are in good agreement with the experimental data, and the dependence of the effective charge on the ionization energy of the projectile is also discussed qualitatively.

Partial-SOI high voltage P-channel LDMOS with interface accumulation holes

A new partial SOI （silion-on-insulator） （PSOI） high voltage P-channel LDMOS （lateral double-diffused metal-oxide semiconductor） with an interface hole islands （HI） layer is proposed and its breakdown characteristics are investigated theoretically. A high concentration of charges accumulate on the interface, whose density changes with the negative drain voltage, which increase the electric field （Er） in the dielectric buried oxide layer （BOX） and modulate the electric field in drift region . This results in the enhancement of the breakdown voltage （BV）. The values of E1 and BV of an HI PSOI with a 2-~m thick SOI layer over a 1-~tm thick buried layer are 580V/~m and -582 V, respectively, compared with 81.5 V/p.m and -123 V of a conventional PSOI. Furthermore, the Si window also alleviates the self-heating effect （SHE）. Moreover, in comparison with the conventional device, the proposed device exhibits low on-resistance.

多次部分充电策略下双车型车辆配送路径研究

针对物流配送过程中燃油车和电动车并存的实际情况,综合考虑多次部分充电策略下双车型、充电设施、碳排放等因素,构建了以车辆使用成本、运输成本(含充电成本)、燃油车碳排放成本之和最小为目标的混合整数线性规划模型。选择某市配送中心为算例进行研究,采用CPLEX求解算例。结果表明:采用多次部分充电策略能进一步缓解“里程焦虑”,提高电动车装载率。之后进行单因素灵敏性分析,分析电动车的续航里程、额定载重量、充电站位置与数量对双车型路径优化结果的影响。

Diagnosing health in composite battery electrodes with explainable deep learning and partial charging data

Lithium-ion batteries with composite anodes of graphite and silicon are increasingly being used. However, their degradation pathways are complicated due to the blended nature of the electrodes, with graphite and silicon degrading at different rates. Here, we develop a deep learning health diagnostic framework to rapidly quantify and separate the different degradation rates of graphite and silicon in composite anodes using partial charging data. The convolutional neural network (CNN), trained with synthetic data, uses experimental partial charging data to diagnose electrode-level health of tested batteries, with errors of less than 3.1% (corresponding to the loss of active material reaching ∼75%). Sensitivity analysis of the capacity-voltage curve under different degradation modes is performed to provide a physically informed voltage window for diagnostics with partial charging data. By using the gradient-weighted class activation mapping approach, we provide explainable insights into how these CNNs work;highlighting regions of the voltage-curve to which they are most sensitive. Robustness is validated by introducing noise to the data, with no significant negative impact on the diagnostic accuracy for noise levels below 10 mV, thus highlighting the potential for deep learning approaches in the diagnostics of lithium-ion battery performance under real-world conditions. The framework presented here can be generalised to other cell formats and chemistries, providing robust and explainable battery diagnostics for both conventional single material electrodes, but also the more challenging composite electrodes.

交联聚乙烯直流电树枝降压阶段的局部放电特性

电树枝是交联聚乙烯(XLPE)高压直流电缆的典型缺陷,有效检测电树枝对电缆绝缘状态评估至关重要。为此对含有电树枝的XLPE针-板绝缘试样进行直流局部放电实验,分析不同阶段下的局部放电特性以及电压参数对放电特性的影响。实验发现:含电树枝的试样在降压过程中会出现局部放电现象,不含电树枝的试样则不会放电;降压过程中的放电具有良好的重复性,对电树枝尺寸无明显影响,且放电脉冲极性与恒压阶段的相反。该实验现象表明利用降压阶段的局部放电检测,可为高压直流电缆电树枝的评估提供一种有益的尝试。此外,实验表明多次局部放电可能导致通道电导率增加,放电熄灭电压增大。不同电压参数下的降压阶段实验结果表明:更高的直流电压,合适的降压速率可以增加放电次数;针电极为负极性时平均放电量更高;恒压时长对放电特性没有显著影响。采用数值仿真分析了降压前后绝缘区域的电场分布,结果表明降压前期,泊松电场的衰减速率低于外施电场的衰减速率,使得针尖附近形成场强较高的反向电场,从而导致降压过程中的局部放电。

Transfer learning from synthetic data for open-circuit voltage curve reconstruction and state of health estimation of lithium-ion batteries from partial charging segments

Data-driven models for battery state estimation require extensive experimental training data,which may not be available or suitable for specific tasks like open-circuit voltage(OCV)reconstruction and subsequent state of health(SOH)estimation.This study addresses this issue by developing a transfer-learning-based OCV reconstruction model using a temporal convolutional long short-term memory(TCN-LSTM)network trained on synthetic data from an automotive nickel cobalt aluminium oxide(NCA)cell generated through a mechanistic model approach.The data consists of voltage curves at constant temperature,C-rates between C/30 to 1C,and a SOH-range from 70%to 100%.The model is refined via Bayesian optimization and then applied to four use cases with reduced experimental nickel manganese cobalt oxide(NMC)cell training data for higher use cases.The TL models’performances are compared with models trained solely on experimental data,focusing on different C-rates and voltage windows.The results demonstrate that the OCV reconstruction mean absolute error(MAE)within the average battery electric vehicle(BEV)home charging window(30%to 85%state of charge(SOC))is less than 22 mV for the first three use cases across all C-rates.The SOH estimated from the reconstructed OCV exhibits an mean absolute percentage error(MAPE)below 2.2%for these cases.The study further investigates the impact of the source domain on TL by incorporating two additional synthetic datasets,a lithium iron phosphate(LFP)cell and an entirely artificial,non-existing,cell,showing that solely the shifting and scaling of gradient changes in the charging curve suffice to transfer knowledge,even between different cell chemistries.A key limitation with respect to extrapolation capability is identified and evidenced in our fourth use case,where the absence of such comprehensive data hindered the TL process.

脉冲电压下油中流注演变规律及放电脉冲特性仿真研究

随着新型电力系统快速发展,油纸绝缘承受的电应力环境更加复杂,其中暂态脉冲下的油纸绝缘放电行为备受关注。为弥补实验研究洞察微观机理能力的不足,基于全电流理论构建油中流注场路耦合模型,研究了脉冲电压下流注演变规律及其影响因素,揭示了放电脉冲波形特性及其与流注演变过程的内在联系。研究表明:暂态脉冲作用下的油中流注可分为球状发展、定向发展、流注消散3个阶段;流注头部场强在球状发展阶段减弱,定向发展阶段维持不变,流注头部净电荷密度始终减弱;起始放电电压的增加、直流分量占比的减小、脉冲陡度的增加均会使流注传播速度与最大半径增加;忽略回路电感作用时,流注将诱发单极性双峰放电脉冲,其中球状发展阶段对应脉冲首峰前沿,定向发展阶段对应首峰下降沿,纸板充电过程对应次峰前沿,电荷消散过程对应次峰下降沿;回路电感将引起放电脉冲的首峰振荡,振荡频率、脉冲幅值均与回路电感近似线性负相关。该研究结果为揭示暂态电应力下油纸绝缘放电机理奠定了理论基础,对统一放电脉冲波形特性具有重要意义。

基于深度强化学习的多充电器部分充电策略

在大规模无线可充电传感器网络(WRSN)中,为了解决可分离充电模式下移动充电车(MCV)充电效率低下的问题,提出一种多充电器部分充电策略(PCSMC),以避免由于等待传感器节点进行完全充电而导致剩余能量低的节点失效。首先将充电时长这种连续动作空间转换为离散的动作空间,然后使用指针网络规划MCV的路径并动态调整传感器节点的充电时长,最后使用深度强化学习算法(DDQN)训练指针网络,从而生成近似最优解。仿真结果表明,与其他充电策略相比,PCSMC在失效节点数和平均充电延迟方面分别降低了23.56%和27.71%。

高功率密度中高频变压器绝缘与散热研究进展与展望

围绕大容量电力电子变压器的发展需求,针对其中关键部件“高功率密度中高频变压器”的绝缘与散热研究进行综述分析。高功率密度对固体绝缘与散热性能提出新的挑战。首先,论述了高功率密度中高频变压器设计与应用时绝缘和散热的矛盾。其次,主要论述了高频绝缘失效的研究进展,包括绝缘击穿、局部放电、沿面放电、电树枝劣化等特性。然后,分析了目前高频绝缘的失效机理研究,包括热击穿、空间电荷效应、高频电导与自由体积效应。最后,论述了高频绝缘寿命的研究,分析了频率、温度、电压变化率du/dt等对绝缘耐电晕寿命的影响以及寿命模型。基于研究进展,提出了高频绝缘与散热的研究展望。该文综述研究对大容量电力电子变压器的设计与应用具有重要意义。

基于节点分级策略的无线可充电传感器网络部分充电算法

提出了一种节点分级策略(node classification strategy,NCS)。根据传感器节点通信数据量和对应的能耗,首先建立传感器节点耗能率模型,然后结合传感器节点耗能率大小和空间距离信息来选择待充电传感器节点,从而提高充电响应的公平性。另外,传统充电算法默认将电池电量补充至最大值,导致被充电的传感器节点个数有限。本文设计了部分充电算法(partial charging algorithm,PCA),通过优化充电值使得充电后既能保证传感器节点工作的电量开销,又能让WCR的有限电量被合理分配给更多有能量需求的传感器节点。最后,仿真实验表明,提出的充电算法NCPCA(node classification and partial charging algorithm)能有效降低网络中传感器节点死亡率,提高WRSNs的工作性能。

基于二阶电路的开关柜局部放电检测方法

为了实现高压开关柜局部放电脉冲的高灵敏度带电检测,提出一种基于二阶电路的开关柜局部放电检测方法。首先,构建了包含带电显示装置与检测阻抗的脉冲检测电路,并测量分析了传感、显示单元的电气参数;然后,提出了适用于带电检测的二阶电路,研究了二阶电路以及带电显示装置的电容、电感参数对安全可靠性和检测灵敏度的影响;最后,利用一台10 kV铠装式开关柜与带电显示装置对该方法进行了测试。结果表明:二阶电路检测阻抗不影响开关柜与带电显示装置的安全运行,其检测灵敏度是安装在开关柜接地线上高频CT(电流互感器)的1.6倍。

N、P/RC@Pb复合材料在铅碳电池负极中的应用

为改善铅碳混合不均和负极析氢的问题,以D418大孔螯合磷酸树脂为碳源,制备出与Pb复合的N、P掺杂碳材料(N、P/RC@Pb)。采用X射线衍射(XRD)、扫描电镜(SEM)等手段对复合材料进行表征,对添加N、P/RC@Pb复合材料的负极板和铅碳电池进行了研究。结果表明:Pb均匀分布在树脂碳表面,以Pb复合物的形式与树脂碳紧密结合。线性伏安(LSV)测试表明:N、P/RC@Pb的添加能有效抑制析氢反应(HER),在-0.46 V下1%N、P/RC@Pb电极板拥有最小的析氢电流(-0.087 A/cm^(2)),更接近空白组(-0.053 A/cm^(2))。在电池循环测试中,添加1%N、P/RC@Pb的模拟电池的循环寿命为1834次,而空白电池循环寿命为837次。在容量测试中,含量为1%的N、P/RC@Pb的电池容量为241.0 mAh,较空白电池(157.8 mAh)提升了53%。N、P/RC@Pb复合材料制备方法简单,价格低廉,改善了铅碳混合不均问题,有效抑制了碳上的析氢反应,在铅碳电池中具有潜在的应用前景。

高频局放带电指示器设计

文章首先分析高频局部放电(以下简称局放)的原理,其次探讨高频局放信号的特征和传播与衰减规律,最后阐述高频局放带电指示器的设计,包括总体架构设计、信号处理电路设计和信号处理算法与软件系统开发。所设计的高频局放带电指示器能够实现对设备带电状态的精准监测,可以快速响应设备带电状态的变化,为电力系统的安全监测和故障预警提供了有效手段。

基于HPLC-CAD指纹图谱结合化学计量分析评价牛黄清心丸(局方)质量

目的 建立牛黄清心丸(局方)的指纹图谱,并通过化学计量学分析手段对影响其质量的关键指标成分进行分析,为牛黄清心丸(局方)的质量控制与评价提供参考。方法 采用高效液相色谱法-电雾式检测器建立牛黄清心丸(局方)指纹图谱,进行方法学考察,并确定其共有峰进行聚类分析、主成分分析和正交偏最小二乘法判别分析。结果 指纹图谱方法学考察结果显示,精密度、稳定性、重复性的相对保留时间和相对峰面积的RSD分别为0.04%~0.06%和1.45%~2.67%,0.04%~0.87%和0.26%~2.87%,0.01%~0.34%和1.72%~2.93%。对照指纹图谱共标记出26个共有峰,其中指认出苦杏仁苷、甘草苷、黄芩苷、胆酸等18个特征峰,相似度为0.927~0.995。聚类分析热图将样品聚为3类,经主成分分析得6个主要成分的累计贡献率到达84.952%,并通过正交偏最小二乘法判别分析预测得到甘草苷、甘草酸铵、升麻素苷、苦杏仁苷4个引起质量差异性的化合物。结论 所建立方法可以分析出不同厂家、同厂家不同批次牛黄清心丸(局方)的质量差异,指纹图谱及化学计量分析方法稳定可行,可全面用于其质量评价。

变压器油中局放UHF信号能量与放电量的关系

为研究变压器油中的金属微粒缺陷下局部放电(PD)放电量与超高频(UHF)信号累积放电能量之间的关系,利用50Ω无感电阻测量电流脉冲和超高频电磁波检测系统,对两种检测方法的实验室人工模拟变压器PD信号进行了测量,发现变压器油中的金属微粒缺陷下的局部放电放电量和UHF信号累积能量之间有二次曲线关系,且当电压与缺陷质量增加时,PD的放电量与天线接收的累计能量均会增加。这一结果表明:结合IEC 60270标准,可以通过计算UHF信号累积能量来获取局部放电量,这为进一步系统研究用超高频法定量检测PD的难题,提供了一种有价值的方法和手段。