基于VMD和DAIPSO-GPR解决容量再生现象的锂离子电池寿命预测研究

锂离子电池应用时表现出的时变、动态、非线性等特征,以及容量再生现象,导致传统模型对锂离子电池剩余使用寿命(RUL)预测的准确性低,该文将变分模态分解(VMD)和高斯过程回归(GPR)以及动态自适应免疫粒子群(DAIPSO)结合,建立RUL预测模型。首先利用等压降放电时间分析法,提取健康因子,利用VMD对其进行分解处理,挖掘数据内在信息,降低数据复杂度,并针对不同分量,利用不同协方差函数建立GPR预测模型,有效捕获了数据的长期下降趋势和短期再生波动。利用DAIPSO算法优化GPR模型,实现核函数超参数的优化,建立了更准确的退化关系模型,最终实现剩余使用寿命的准确预测,以及不确定性表征。最后利用NASA电池数据进行验证,离线预测结果表明所提方法具有较高预测精度和泛化适应能力。     

一种目标特性辅助的积分粒子滤波新方法

针对非均匀稀疏采样环境下目标跟踪中的非线性滤波问题,提出了一种基于Gauss-Hermite积分和目标特性辅助的积分粒子滤波新方法(AQPF).在该方法中,构建了基于Gauss-Hermite积分的积分点概率密度函数作为重要性密度函数,同时,在时间更新阶段引入目标观测、目标观测的有效时间间隔、目标速度等目标特性,综合改善滤波器中预测粒子和预测协方差估计的准确性和粒子的多样性,有效提高目标状态的估计性能.实验结果表明,提出方法的估计性能要明显好于无迹kalman滤波(UKF)、积分kalman滤波(QKF)、粒子滤波(PF)、辅助粒子滤波(APF)和高斯粒子滤波(GPF),能够有效对目标状态进行估计.     

基于分层极限学习机的锂离子电池剩余使用寿命预测

提前对锂离子电池的剩余使用寿命（RUL）进行预测可以保证电池及其应用设备安全稳定地运行。针对目前预测方法的结果滞后且缺乏实际意义等问题,为了利用电池前期的少量循环数据实现RUL的提前预测,本文基于原始极限学习机和自动编码器构建了分层极限学习机（H-ELM）预测模型。然后选取丰田研究所（TRI）的实验数据集对H-ELM完成了仿真实验验证。实验结果表明,本文提出的H-ELM预测模型可以在电池使用初期预测出RUL,同时预测结果的平均绝对百分比误差（MAPE）仅有10.14%。     

低复杂度的MIMO系统粒子滤波检测

该文通过降低采样大小和信号检测搜索空间给出了两种低复杂度的多输入多输出(MIMO)系统粒子滤波(PF)检测方法:球形约束PF和多层映射PF。在球形约束PF中,首先基于迫零原则求得所需的球形约束,然后利用该球形约束减少粒子滤波过程中每一级重要性采样生成的粒子数。多层映射PF则采用多层映射将大小为4L的正交幅度调制(QAM)星座划分为L个4-QAM星座的级联以降低信号检测的搜索范围。计算机仿真结果表明,第1种方法能够在大发送天线数的情况下保持系统性能且有效地降低粒子滤波的计算复杂度;而第2种方法能够以较低的错误性能损失为代价获得计算复杂度的极大降低。     

非均匀稀疏采样环境的改进高斯粒子滤波方法

粒子滤波（PF）技术的研究一直是非线性滤波领域的热点和难点问题,针对非均匀稀疏采样环境下传感器观测的滤波估计问题,提出了一种结合目标运动特性的改进型高斯粒子滤波方法。在该方法中,首先深入分析了传统粒子滤波不能有效对非均匀稀疏采样观测数据进行有效处理的原因,通过引入目标观测、目标观测的有效时间间隔、目标速度等目标特性,综合改善高斯粒子滤波器在时间更新阶段预测粒子和预测协方差估计的准确性,从而提高观测更新阶段重要性密度函数的估计精度,实现对目标状态的精确估计。实验结果表明,对于一维非线性非高斯例子,提出方法要稍好于传统的PF、辅助粒子滤波（APF）和高斯粒子滤波（GPF）;而对于实际的非均匀稀疏采样观测样本,提出方法要远好于PF、APF和GPF,能够有效对目标进行状态估计。      

基于RTS-IEKPF算法的锂电池SOC估算

针对瞬间大电流充放电使电池非线性加剧,使用迭代扩展卡尔曼滤波算法(IEKF)估算电池荷电状态(SOC)时会有较大误差。为了减小误差,进一步提高SOC的估算精度,提出一种基于锂电池复合电化学模型的融合RTS最优平滑的迭代扩展卡尔曼粒子滤波算法(RTS-IEKPF)。该方法利用RTS(Rauch-Tung-Streibel)最优平滑算法与IEKF算法结合生成粒子滤波的建议分布,得到RTS-IEKPF,并用该方法来估算锂电池的SOC。实验结果表明,RTS-IEKPF算法SOC的估算精度优于PF,IEKF和IEKPF算法SOC的估算精度。     

基于粒子滤波的动态自回归预测模型方法

针对自回归模型以固定历史观测序列建模,模型不能随时间序列新的观测值实时更新,导致预测中对序列趋势变化适应性差,预测精度低的问题,提出以粒子滤波动态优化调整自回归模型的方法,通过对模型参数蒙特卡洛采样得到粒子,以粒子描述模型状态变量的演变,采用递推贝叶斯方法估计粒子权重,由粒子及其权重近似模型参数的后验滤波值,从而随观测序列的动态获得不断更新模型参数,提高了模型预测结果的精确性,并能给出预测结果的置信区间。最后以NASA艾姆斯中心锂离子电池试验数据为例,验证了该方法的有效性。     

改进粒子滤波算法在目标状态估计中的应用

针对粒子滤波算法(PF)建议性函数的选择问题和粒子匮乏现象,提出了改进粒子滤波算法.该算法利用无迹卡尔曼滤波(UKF)产生建议性分布,提高估计精度;采用马尔科夫蒙特卡罗法(MCMC)保持粒子多样性,抑制粒子匮乏现象.仿真结果表明该算法的目标状态估计精度明显优于PF、UPF、PF-MCMC和PF-EKF-MCMC算法.     

基于DEPSO-RVM的B787电池剩余寿命预测

锂离子电池已经被应用于B787客机,为进一步提高B787锂离子电池的可靠性,针对传统基于相关向量机的电池剩余使用寿命预测方法的不足,提出一种把相关向量机、差分进化算法和粒子群优化算法融合的的方法。通过差分进化算法和粒子群优化算法对相关向量机的参数进行优化,增强其对电池历史监测数据退化趋势的预测能力。应用卡尔曼滤波器对融合算法实施优化,将优化后的预测结果作为在线样本添加到训练集中,对提出的模型重新训练,以此来动态调整系数矩阵和相关向量以执行下一次迭代预测。基于B787锂离子电池测量数据,对所提方法的有效性和鲁棒性进行了验证。     

杂波环境下的粒子滤波器数据关联方法

为了解决杂波环境下多机动目标的数据关联难题,提出了一种将粒子滤波器(PF)和联合概率数据关联(JPDA)相结合的数据关联算法,该方法首先应用粒子滤波方法对目标的状态进行采样,得到样本(粒子),并结合量测,通过JPDA方法计算得到联合互连事件的关联概率,而该关联概率实际上就是PF中粒子的权值。通过选取适当的有效采样尺度作为衡量PF退化现象的测度,采用重要性重采样技术克服了标准PF的退化现象,降低了算法的计算量。仿真结果表明,粒子滤波方法可以较好地解决杂波环境下跟踪多机动目标的数据关联问题;重要性重采样PF的计算复杂度低于标准PF。     

Lithium-ion batteries remaining useful life prediction based on a mixture of empirical mode decomposition and ARIMA model

Prediction of lithium-ion batteries remaining useful life (RUL) plays an important role in battery management system (BMS) used in electric vehicles. A novel approach which combines empirical mode decomposition (EMD) and autoregressive integrated moving average (ARIMA) model is proposed for RUL prognostic in this paper. At first, EMD is utilized to decouple global deterioration trend and capacity regeneration from state-of-health (SOH) time series, which are then used in ARIMA model to predict the global deterioration trend and capacity regeneration, respectively. Next, all the separate prediction results are added up to obtain a comprehensive SOH prediction from which the RUL is acquired. The proposed method is validated through lithium-ion batteries aging test data. By comparison with relevance vector machine, monotonic echo sate networks and ARIMA methods, EMD-ARIMA approach gives a more satisfying and accurate prediction result.     

Prognostics of Lithium-ion batteries based on state space modeling with heterogeneous noise variances

Prognostics and health management of lithium-ion batteries, especially their remaining useful life (RUL) prediction, has attracted much attention in recent years because accurate battery RUL prediction is beneficial to ensuring high reliability of lithium-ion batteries for providing power sources for many electronic products. In the common state space modeling of battery RUL prediction, noise variances are usually assumed to be fixed. However, noise variances have great influence on state space modeling. If noise variances are too small, it takes long time for initial guess states to approach true states, and thus estimated states and measurements are biased. If noise variances are too large, state space modeling based filtering will suffer divergence. Besides, even though a same type of lithium-ion batteries are investigated, their degradation paths vary quite differently in practice due to unit-to-unit variation, ambient temperature and other working conditions. Consequently, heterogeneity of noise variances should be taken into consideration in state space modeling so as to improve RUL prediction accuracy. More importantly, noise variances should be posteriorly updated by using up-to-date battery capacity degradation measurements. In this paper, an efficient prognostic method for battery RUL prediction is proposed based on state space modeling with heterogeneity of noise variances. 26 lithium-ion batteries degradation data are used to illustrate how the proposed prognostic method works. Some comparisons with other common prognostic methods are conducted to show the superiority of the proposed prognostic method.     

Data-driven hybrid remaining useful life estimation approach for spacecraft lithium-ion battery

Electrical power system (EPS) is one of the most critical sub-systems of the spacecraft. Lithium-ion battery is the vital component is the EPS. Remaining useful life (RUL) prediction is an effective mean to evaluate the battery reliability. Autoregressive model (AR) and particle filter (PF) are two traditional approaches in battery prognosis. However, the parameters in a trained AR model cannot be updated which will cause the under-fitting in the long term prediction and further decrease the RUL prediction accuracy. On the other hand, the measurement function in the PF algorithm cannot be obtained in the long term prediction process. To address these two challenges, a hybrid method of IND-AR model and PF algorithm are proposed in this work. Compared with basic AR model, a nonlinear degradation factor and an iterative parameter updating method are utilized to improve the long term prediction performance. The capacity prediction results are applied as the measurement function for the PF algorithm. The nonlinear degradation factor can make the linear AR model suitable for nonlinear degradation estimation. And once the capacity is predicted, the state-space model in the PF is activated to obtain an optimized result. Optimized capacity prediction result of each cycle is utilized to re-train the regression model and update the parameters. The predictor keeps working iteratively until the capacity hit the failure threshold to calculate the RUL value. The uncertainty involved in the RUL prediction result is presented by PF algorithm as well. Experiments are conducted based on commercial lithium-ion batteries and real-applied satellite lithium-ion batteries. The results have high accuracy in capacity fade prediction and RUL prediction of the proposed method. The real applied lithium-ion battery can meet the requirement of spacecraft. All the experiments results show great potential of the proposed framework.     

An improved unscented particle filter approach for lithium-ion battery remaining useful life prediction

Lithium-ion rechargeable batteries are widely used as power sources for mobile phones, laptops and electric cars, and gradually extended to military communication, navigation, aviation, aerospace and other fields. Accurate remaining useful life (RUL) prediction of lithium-ion battery plays an important role in avoiding serious security and economic consequences caused by failure to supply required power levels. Thus, the RUL prediction for lithium-ion battery has become a critical task in engineering practices. With its superiority in handling nonlinear and non-Gaussian system behaviors, the particle filtering (PF) technique is widely used in the remaining life prediction. However, the choice of importance function and the degradation of diversity in sampling particles limit the estimation accuracy. This paper presents an improved PF algorithm, that is, the unscented particle filter (UPF) based on linear optimizing combination resampling (U-LOCR-PF) to improve the prediction accuracy. In one aspect, the unscented Kalman filter (UKF) is used to generate a proposal distribution as an importance function for particle filtering. In the other aspect, the linear optimizing combination resampling (LOCR) algorithm is used to overcome the particle diversity deficiency. It should be noted that the step coefficient K can affect the performance of LOCR algorithm, and the fuzzy inference system is applied to determine the value of step coefficient K. According to the analysis results, it can be seen that the proposed prognostic method shows higher accuracy in the RUL prediction of lithium-ion battery, compared with the existing PF-based and UPF-based prognostic methods.     

多核相关向量机优化模型的锂电池剩余寿命预测方法

基于相关向量机的剩余寿命预测方法,核函数是影响相关向量机模型预测性能的重要因素.目前的相关向量机预测模型以单核为主,且核函数的选择存在较大主观性,导致所构建的预测模型性能有限.本文提出一种融合多个核函数构建相关向量机预测模型的方法,通过果蝇算法优化多个核函数优化组合的线性方程系数,提高了模型的预测性能,并将该方法应用于预测锂离子电池的循环剩余寿命.分别采用美国NASA和马里兰大学的电池退化数据集,对本文的方法进行了实验验证.实验结果表明：多核相关向量机预测方法的平均绝对误差和均方根误差都小于最优的单核相关向量机预测方法.     

基于扩展卡尔曼滤波模型的电动汽车锂电池SOC估算研究

针对新能源电动汽车锂电池电荷状态SOC估算问题,在锂电池二阶RC等效电路模型基础上,引入扩展卡尔曼滤波方法,利用扩展卡尔曼滤波方法处理复杂非线性系统能力,建立了扩展卡尔曼滤波锂电池SOC估算模型,并通过MATLAB/Simulink对新建模型仿真分析。仿真结果显示,建立的扩展卡尔曼滤波锂电池SOC估算模型具有较高估算精度,整体误差小于±0.05%,满足新能源电动汽车对锂电池SOC估算要求。     

Battery remaining useful life prediction at different discharge rates

Lithium-ion batteries are widely used in hybrid electric vehicles, consumer electronics, etc. As of today, given a room temperature, many battery prognostic methods working at a constant discharge rate have been proposed to predict battery remaining useful life (RUL). However, different discharge rates (DDRs) affect both usable battery capacity and battery degradation rate. Consequently, it is necessary to take DDRs into consideration when a battery prognostic method is designed. In this paper, we propose a discharge-rate-dependent battery prognostic method that is able to track usable battery capacity affected by DDRs in the process of battery degradation and to predict RUL at DDRs. An experiment was designed to collect accelerated battery life testing data at DDRs, which are used to investigate how DDRs influence usable battery capacity, to design a discharge-rate-dependent state space model and to validate the effectiveness of the proposed battery prognostic method. Results show that the proposed battery prognostic method can work at DDRs and achieve high RUL prediction accuracies at DDRs.     

Interacting multiple model particle filter for prognostics of lithium-ion batteries

We propose a new data-driven prognostic method based on the interacting multiple model particle filter (IMMPF) for determining the remaining useful life (RUL) of lithium-ion (Li-ion) batteries and the probability distribution function (PDF) of the associated uncertainty. The method applies the IMMPF to different state equations. Modeling the battery capacity degradation is very important for predicting the RUL of Li-ion batteries. In this study, improvements are made on various Li-ion battery capacity models (i.e., polynomial, exponential, and Verhulst models). Further, three different one-step state transition equations are developed, and the IMMPF method is applied to estimate the RUL of Li-ion batteries with the use of the three improved models. The PDF of the predicted RUL is obtained by combining the PDFs obtained with each individual model. We conduct four case studies to validate the proposed method. The results are as follows: (1) the three improved models require fewer parameters than the original models, (2) the proposed prognostic method shows stable and high prediction accuracy, and (3) the proposed method narrows the uncertainty PDF of the predicted RUL of Li-ion batteries.     

Multi-Scale Prediction of RUL and SOH for Lithium-Ion Batteries Based on WNN-UPF Combined Model

The prediction of Remaining useful life (RUL) and the estimation of State of health (SOH) are extremely important issues for operating performance of Lithium-ion (Li-ion) batteries in the Battery management system (BMS). A multi-scale prediction approach of RUL and SOH is presented, which combines Wavelet neural network (WNN) with Unscented particle filter (UPF) model. The capacity degradation data of Li-ion batteries are decomposed into the low-frequency degradation trend and high-frequency fluctuation components by Discrete wavelet transform (DWT). Based on the WNN-UPF model, the long-term RUL of Li-ion batteries is predicted with the low-frequency degradation trend data. The high-frequency fluctuation data and RUL prediction results are integrated effectively to estimate the short-term SOH of Li-ion batteries. The experimental results show that the proposed method achieves high accuracy and strong robustness, even if the prediction starting point is set to the early stage of Li-ion batteries' lifespan.