The current research of state of charge(SoC) online estimation of lithium-ion battery(LiB) in electric vehicles(EVs)mainly focuses on adopting or improving of battery models and estimation filters. However, little attention has been paid to the accuracy of various open circuit voltage(OCV) models for correcting the SoC with aid of the ampere-hour counting method. This paper presents a comprehensive comparison study on eighteen OCV models which cover the majority of models used in literature. The low-current OCV tests are conducted on the typical commercial LiFePO_4/graphite(LFP) and LiNiMnCoO_2/graphite(NMC) cells to obtain the experimental OCV-SoC curves at different ambient temperature and aging stages. With selected OCV and SoC points from experimental OCV-SoC curves, the parameters of each OCV model are determined by curve fitting toolbox of MATLAB 2013. Then the fitting OCV-SoC curves based on diversified OCV models are also obtained. The indicator of root-mean-square error(RMSE) between the experimental data and fitted data is selected to evaluate the adaptabilities of these OCV models for their main features, advantages,and limitations. The sensitivities of OCV models to ambient temperatures, aging stages, numbers of data points,and SoC regions are studied for both NMC and LFP cells. Furthermore, the influences of these models on SoC estimation are discussed. Through a comprehensive comparison and analysis on OCV models, some recommendations in selecting OCV models for both NMC and LFP cells are given. 相似文献
Platelike α‐Al2O3 powder was obtained at 850°C by thermal decomposition of ammonium aluminum carbonate hydroxide precursor, which was treated by hydrofluoric acid. The results showed the decomposition of the as‐prepared precursors experienced via three steps, adsorption of physical water, dehydration of crystalline water, and decomposition of the precursor, and the activation energies of the above three steps were calculated using the Coats–Redfern method. Meanwhile, the intermediate of (NH4)3AlF6 obtained played an important role in decreasing activation energy of the decomposition and phase transformation. Moreover, the thermal conductivity of the epoxy resin filled with platelike alumina was improved obviously. 相似文献
For a constant aerosol concentration, it is traditionally assumed that a Poisson process describes the behavior of particle detections during sampling and consequently fluctuations in the measured concentration. Recent studies, however, have shown that sampling of micrometer-sized aerosols has non-Poissonian behavior with positive correlations. The validity of the Poisson assumption for nanometer-sized aerosols has not been established and thus was tested in this study. Its validity was tested for four particle sizes—10 nm, 25 nm, 50 nm, and 100 nm—by sampling from indoor air with a differential mobility analyzer-condensation particle counter (DMA-CPC) setup to obtain a time series of particle counts. Five metrics were calculated from the data: pair-correlation function (PCF), scaled clustering index (SCI), coefficient of variation, probability of measuring a concentration at least 25% greater than average, and posterior distributions from Bayesian inference. To identify departures from Poissonian behavior, these metrics were also calculated for 1000 computer-generated Poisson time series with the same mean as the experimental data. For most comparisons, the experimental data fell within the range of 80% of the Poisson-simulation values. Essentially, the metrics for the experimental data were mostly indistinguishable from a simulated Poisson process. The greater influence of Brownian motion for nanometer-sized aerosols may explain the Poissonian behavior observed for smaller aerosols. Although the Poisson assumption was found to be reasonable in this study it must be carefully applied, as the results here do not definitively prove applicability in all sampling situations.
Copyright 2014 American Association for Aerosol Research 相似文献
By using Cinchona‐derived chiral phosphines as catalytic ligands, enantioenriched cis‐3a,8a‐hexahydropyrrolo[2,3‐b]indoles (ent‐HPIs), which are core scaffolds in a large array of biologically active natural products, can be convergently assembled under mild conditions through the silver(I)‐catalyzed asymmetric domino reaction of readily available isocyanoacetates and 2‐(2‐aminophenyl)acrylates. Various functionalities can be tolerated in the reaction, affording enantioenriched HPIs in high overall yields and good enantioselectivities (up to 92% ees).
