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Today it is standard to use equivalent circuit models to describe the dynamic behavior of Li-ion vehicle batteries. The parameters and states change with operating point and are therefore continuously estimated using bayesian observers, though without knowing to what degree the performance can be improved. Posterior Cramér-Rao Lower Bounds (CRLBs) can be used to theoretically quantify the optimal...
In this study, Thévenin-equivalent circuit-based lithium-ion battery is modeled for State of Charge (SoC) estimation via sliding mode technique. Internal resistance and open-circuit potentials for different charge and discharge rates are included as look-up tables for precise energy based modeling of the lithium-ion battery. A solution for SoC estimation is proposed under two assumptions which simplifies...
This paper presents a state-of-health (SOH) estimation method for lithium-ion batteries in electric vehicles, by identifying the bulk capacitance of its equivalent RC circuit model. A novel algorithm is discussed to derive the attenuation factor of the bulk capacitance in different cycles. A discrete nonlinear observer is also designed so that the bulk capacitance can be successfully identified to...
This work presents a modeling and estimation techniques for State of Charge and State of Health estimation for Li-ion batteries. The analysis is done using an adaptive estimation approach for joint state and parameter estimation and by simplifying an existing nonlinear model previously obtained from experiments tests. A switching mechanism between two observers, one for the charging phase and one...
Energy storage systems in Smart Grid applications can provide key services to transform the current power system through large-scale integration of renewable energy sources. They can assist in stabilizing the intermittent energy production, improve power quality and mitigate system peak loads. With the integration of energy storage systems into the grid, accurate and adaptive modeling becomes a necessity,...
We developed a robust state-of-charge (SOC) estimation algorithm which considers uncertainties of matrix including internal resistance for Li-Ion battery. We used a linear matrix inequality (LMI) to acquire gain of the observer for estimating SOC. The algorithm is less accurate than estimation results of other algorithms, but has simple and fast calculation by using a time-invariant observer gain...
The battery state of charge (SOC) is an important parameter of the battery capacity state. It can only be indirectly estimated through measurable variables such as voltage, current and temperature. Accurate estimation of SOC is one of the key problems in a battery management system. A battery model based on equivalent electrical circuits has been used to describe the battery dynamics. The model has...
In this paper, an adaptive observer is applied to estimate the internal temperature of a lithium-ion cell in a battery pack. The cell's internal temperature is an important factor for its degradation, but it cannot be measured directly. Based on the measured surface temperature and a lumped thermal model for the battery pack, an adaptive observer is designed to estimate the internal temperature and...
The work presented in this paper focus on the FORMID authoring tool, pointing out the scenario model which defines within the learning tasks what teachers wish to be observable at runtime. Inspired by a learning design approach, FORMID scenarios authored by teachers are computable and, once validated, automatically deliverable to learners. Moreover, a web-based interface is automatically built for...
Since an autonomous mobile robot often works with various tasks in different environments, the current of battery onboard is time-varying, hence the battery internal resistance is variable. This paper presents an estimation method for battery State of Charge (SOC) based on an H∞ observer to deal with the effect of the modeling errors caused by the variation of the internal resistance. The observer...
Temperature monitoring is a critical issue for lithium ion batteries. Since only the surface temperature of the battery can be measured, a thermal model is needed to estimate the core temperature, which can be higher and hence more critical. In this paper, an on-line parameter identification scheme is designed for a cylindrical lithium ion battery thermal model, by which the parameters of the thermal...
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