Coupled Mechanical-Electrical-Thermal Modeling of Electric Contacts by F.E.M (original) (raw)
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Journal of Power Sources, 2015
In order to better understand the behavior of Lithium-ion batteries under mechanical abuse, a coupled modeling methodology encompassing the mechanical, thermal and electrical response is presented for predicting short circuit under external crush. The combined mechanical-electric-thermal response is simulated in a commercial finite element software LS-DYNA® using a representative-sandwich finite-element model, where electrical-thermal modeling is conducted after an instantaneous mechanical crush. The model includes an explicit representation of each individual component such as the active material, current collector, separator, etc., and predicts their mechanical deformation under quasi-static compression and indentation. Model predictions show good agreement with experiments: the fracture of the battery structure under an indentation test is accurately predicted. The electrical-thermal simulation predicts the current density and temperature distribution in a reasonable manner. Whereas previously reported models consider the mechanical response exclusively, we use the electrical contact between active materials following the failure of the separator as a criterion for short circuit. These results are used to build a lumped-representative sandwich model that is computationally efficient and captures behavior at the cell level without resolving the individual layers.
Thermal Model of Electrical Contacts Based on Experimental Data
2008 Proceedings of the 54th IEEE Holm Conference on Electrical Contacts, 2008
The paper presents statistical analysis of experimental results received in direct temperature measurement of energized electrical contacts of low voltage circuit breaker in laboratory setup. Thermal study was performed on electrical contacts of 3200 Amp low voltage circuit breaker in good conditions and in artificially "aged" conditions. Experimental data have been collected on four contact points on each of three phases of circuit breaker loaded in the range from 50 to 105 % of maximum rated current with 5% increment. The points of direct temperature measurement have been located at different distances from "aged" contact. The goal was to find mathematical model that could reliably define the relationship between temperature rise on electrical connections and current changing in wide range. Data analysis showed that with high degree of confidence the temperature-current relationship could be described using relatively simple function. This approach allows defining a single factor changing with connection deterioration resulting in resistance rise, which in turn makes possible to develop an algorithm for the diagnostic of the change of energized electrical contact physical condition in timely manner.
Electro-Thermal Simulation of Lithium Ion Batteries for Electric and Hybrid Vehicles
A lithium ion battery is analyzed with regard to its thermal behaviour using modelling. Therefore resistive energy losses are translated into generated heat inside the battery, which is evacuated by forced convection, thus forming an electro-thermal model. Based on that model, simulations are done using OpenFOAM. The simulation underlines the observation that batteries have higher temperature close to the connectors and that temperature increase depends highly on discharge rate.
Energies, 2019
Current studies on the mechanical abuse of lithium-ion batteries usually focus on the mechanical damage process of batteries inside a jelly roll. In contrast, this paper investigates the internal short circuits inside batteries. Experimental results of voltage and temperature responses of lithium-ion batteries showed that battery internal short circuits evolve from a soft internal short circuit to a hard internal short circuit, as battery deformation continues. We utilized an improved coupled electrochemical-electric-thermal model to further analyze the battery thermal responses under different conditions of internal short circuit. Experimental and simulation results indicated that the state of charge of Li-ion batteries is a critical factor in determining the intensities of the soft short-circuit response and hard short-circuit response, especially when the resistance of the internal short circuit decreases to a substantially low level. Simulation results further revealed that the ...
Batteries, 2016
Within the scope of developing a multi-physical model describing battery behavior during and after the mechanical load (accelerations, intrusions) of a vehicle's high voltage battery, an internal short circuit model is of deep interest for a virtual hazard assessment. The internal short resistance and the size of the affected area must be known as a minimum for determining the released heat and, in consequence, the temperatures. The internal short resistance of purpose-built dummy pouch cells, filled with electrolyte-like solvent without conductive salt, has thus been measured in a given short area under various compressive loads. The resistances for different short scenarios obtained are analyzed and described in a mathematical form. Short circuit experiments with dummy cells using an external power source have also been carried out. This setup allows the measurement of the temperature evolution at a known current and a determination of the actual short resistance. The post-mortem analysis of the samples shows a correlation between the maximum temperatures, released short heat and the separator melt diameter.
Heating Effects of Short-Circuit Current Impulses on Contacts and Conductors—Part II
IEEE Transactions on Power Delivery, 2008
An analytical description combined with the finite-element calculations of the current displacement caused by short-circuit current impulses in 1-D and 2-D conductor models is presented. It is shown that in many cases, the Joule integral used in the technical practice gives a false representation of the thermal stress in the conductors and contacts. A simplified method is given for determining the degree of current displacement caused by different current impulses, hence, the nonuniformity of the losses and the heating within the conductors.
Electro-thermal modeling and experimental validation for lithium ion battery
Journal of Power Sources, 2011
Thermal management is crucial for improving the charge-discharge efficiency and cycling life of lithium ion battery. In this paper, a mathematical model coupling electronic conduction, mass transfer, energy balance and electrochemical mechanism is developed. Lithium ion diffusivity and chemical reaction rate of cathode material are estimated by comparing simulated results with experimental data of pulse test at various current charge-discharge rates (0.2C, 0.5C, 1C, 2C) and operating temperatures (0 • C, 10 • C, 25 • C, 55 • C). The modeling results are further validated in aspects of electrochemical performance, thermal performance and electrochemical-thermal coupling effects, which show well agreement between the modeling results and experimental results. The modeling results show that lithium ion concentration gradient in both liquid phase and solid phase are greatly affected by temperature, and the lithium ion concentration gradient increase when temperature decrease. This phenomenon results in the capacity losses and power loses of lithium ion battery during low temperature operation. The reversible heat generation during charging process is equal with the heat consumption during discharging process. It is also indicated that the reversible heat is dominant at low rate discharging process and irreversible heat is dominant at high rate discharging process. Proper cooling system should be added to keep battery temperature within safety range during high rate current charging/discharging.
Journal of Power Sources, 2011
Lithium-ion (Li-ion) batteries are favored in hybrid-electric vehicles and electric vehicles for their outstanding power characteristics. In this paper the energy loss due to electrical contact resistance (ECR) at the interface of electrodes and current-collector bars in Li-ion battery assemblies is investigated for the first time. ECR is a direct result of contact surface imperfections, i.e., roughness and out-of-flatness, and acts as an ohmic resistance at the electrode-collector joints. A custom-designed testbed is developed to conduct a systematic experimental study. ECR is measured at separable bolted electrode connections of a sample Li-ion battery, and a straightforward analysis to evaluate the relevant energy loss is presented. Through the experiments, it is observed that ECR is an important issue in energy management of Li-ion batteries. Effects of surface imperfection, contact pressure, joint type, collector bar material, and interfacial materials on ECR are highlighted. The obtained data show that in the considered Li-ion battery, the energy loss due to ECR can be as high as 20% of the total energy flow in and out of the battery under normal operating conditions. However, ECR loss can be reduced to 6% when proper joint pressure and/or surface treatment are used. A poor connection at the electrode-collector interface can lead to a significant battery energy loss as heat generated at the interface. Consequently, a heat flow can be initiated from the electrodes towards the internal battery structure, which results in a considerable temperature increase and onset of thermal runaway. At sever conditions, heat generation due to ECR might cause serious safety issues, sparks, and even melting of the electrodes.
Journal of The Electrochemical Society
This paper presents a novel model for analyzing thermal runaway in Li-ion battery cells with an internal short circuit device implanted in the cell. The model is constructed using Arrhenius formulations for representing the self-heating chemical reactions and the State of Charge. The model accounts for a local short-circuit, which is triggered by the device embedded in the cell windings (jelly roll). The short circuit is modeled by calculating the total available electrical energy and adding an efficiency factor for the conversion of electric energy into thermal energy. The efficiency factor also accounts for the energy vented from the cell. The results show good agreement with the experimental data for two cases-a 0D model and a 3D model of a single cell. Introducing the efficiency factor and simplifying the short-circuit modeling by using an Arrhenius formulation reduces the calculation time and the computational complexity, while providing relevant results about the temperature dynamics. It was found that for an 18650 NCA/graphite cell with a 2.4 Ah capacity, 28% of the electrical energy leaves with the effluent.
A Simplified Mathematical Model for Heating-Induced Thermal Runaway of Lithium-Ion Batteries
Journal of The Electrochemical Society, 2021
The present study aims to develop a simplified mathematical model for the evolution of heating-induced thermal runaway (TR) of lithium-ion batteries (LIBs). This model only requires a minimum number of input parameters, and some of these unknown parameters can be obtained from accelerating rate calorimeter (ARC) tests and previous studies, removing the need for detailed measurements of heat flow of cell components by differential scanning calorimetry. The model was firstly verified by ARC tests for a commercial cylindrical 21700 cell for the prediction of the cell surface temperature evolution with time. It was further validated by uniform heating tests of 21700 cells conducted with flexible and nichrome-wire heaters, respectively. The validated model was finally used to investigate the critical ambient temperature that triggers battery TR. The predicted critical ambient temperature is between 127 °C and 128 °C. The model has been formulated as lumped 0D, axisymmetric 2D and full 3D...