Li-NMC Batteries Model Evaluation with Experimental Data for Electric Vehicle Application

This paper presents a characterization of Nickel Manganese Cobalt (NMC) Lithium-Ion (Li-ion) batteries based on empirical tests to improve online state estimation. It investigates how battery degradation affects the battery management systems (BMS) ability to estimate the state of charge (SOC) and state of health (SOH). The testing is conducted on 8 NMC 18650 Li-ion battery cells split up in two groups of four new and four degraded cells with an SOH of 90%. As both the SOC and the SOH estimations are dependent on the relation between the SOC and the open circuit voltage (OCV), the necessary relaxation time to achieve a stable OCV as well as the SOC-OCV relations dependency on temperature and ageing are derived. The relaxation time needed to achieve a stabilised terminal voltage is, in the worst case, found to be equal to 20 minutes for both the new and the degraded cells. The SOC-OCV curve is not changing significantly when the operation temperature is increased from 23 • C to 45 • C, which is also the case for both the new and the degraded cells. The internal battery resistance and capacitance are however found to depend significantly on both the SOC and operation temperature. A first order RC representation is derived for different SOC and temperatures levels.

show abstract

“…SOC is defined in (1) as the specific charge in Ah, Q Ah , relative to the total capacity, Q Ah,f ull , in Ah [11]. Q Ah is calculated as in (6):…”

Section: Methodsmentioning

confidence: 99%

“…A precise characterization is also fundamental in making accurate models of the batteries. Modelling can be used to quantify and predict battery behavior, such as the degradation, which is an important aspect in utilizing batteries [6,7].…”

Section: Introductionmentioning

confidence: 99%

Characterization of NMC Lithium-ion Battery Degradation for Improved Online State Estimation

Thingvad

Calearo

Thingvad

et al. 2020

2020 55th International Universities Power Engineering Conference (UPEC)

View full text Add to dashboard Cite

show abstract

“…The lithium-ion (Li-ion) batteries are the promising choice for battery storage systems because of their high energy density [6], light weight and long-life cycle [7]. The experiments and modeling on Li-ion batteries (LTO [8], NMC [9], LFP [10], and Li-S [11]) for EV applications have been reported by a number of academic researchers. To guarantee the safety and reliability operation of the battery, a high-performance battery management system (BMS) is needed to monitor and control the voltage, current, temperature, state of the battery and cell balancing [12,13].…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study on the Parameter Identification of an Equivalent Circuit Model for an Li-ion Battery Based on Different Discharge Tests

Poopanya

Sivalertporn

Phophongviwat

2022

WEVJ

View full text Add to dashboard Cite

An effective model of battery performance is important for battery management systems to control the state of battery and cell balancing. The second-order equivalent circuit model of a lithium-ion battery is studied in the present paper. The identification methods that include the multiple linear regression (MLR), exponential curve fitting (ECF) and Simulink design optimization tool (SDOT), were used to determine the model parameters. The aim of this paper is to compare the validity of the three proposed algorithms, which vary in complexity. The open circuit voltage was measured based on the pulse discharge test. The voltage response was collected for every 10% SOC in the interval between 0–100% SOC. The battery voltages calculated from the estimated parameters under the constant current discharge test and dynamic discharge tests for electric vehicles (ISO and WLTP) were compared to the experimental data. The mean absolute error and root mean square error were calculated to analyze the accuracy of the three proposed estimators. Overall, SDOT provides the best fit with high accuracy, but requires a heavy computation burden. The accuracy of the three methods under the constant current discharge test is high compared to other experiments, due to the nonlinear behavior at a low SOC. For the ISO and WLTP dynamic tests, the errors of MLR are close to that of SDOT, but have less computing time. Therefore, MLR is probably more suitable for EV use than SDOT.

show abstract

“…Validation includes verifying the model behavior while performing the application it is developed for [32,33]. Most of the models present in literature are tested on standard full cycles (complete charge and discharge at constant power) or pulse cycles (to analyze step response) [12,13,16,34]. To avoid disregarding some peculiar behaviors, validation of BESS models should implement tests on real-world operations (e.g., frequency regulation).…”

Section: Introductionmentioning

confidence: 99%

“…The proposed laboratory protocol for BESS characterization does not require expensive measurement set and allows to operate with probes at the switchboard level and not at the cell level, oppositely to the most widespread approaches [12,34,38,39]. This allows a user to replicate the experimental tests in most facilities (i.e., with commercial power analyzers) and to repeat the procedure periodically to also take into account the state-of-health (SOH) evolution of the battery (given obvious time constraints, it has not been possible to include SOH analysis in this paper).…”

mentioning

confidence: 99%

Modeling a Large-Scale Battery Energy Storage System for Power Grid Application Analysis

et al. 2019

View full text Add to dashboard Cite

The interest in modeling the operation of large-scale battery energy storage systems (BESS) for analyzing power grid applications is rising. This is due to the increasing storage capacity installed in power systems for providing ancillary services and supporting nonprogrammable renewable energy sources (RES). BESS numerical models suitable for grid-connected applications must offer a trade-off, keeping a high accuracy even with limited computational effort. Moreover, they are asked to be viable in modeling for real-life equipment, and not just accurate in the simulation of the electrochemical section. The aim of this study is to develop a numerical model for the analysis of the grid-connected BESS operation; the main goal of the proposal is to have a test protocol based on standard equipment and just based on charge/discharge tests, i.e., a procedure viable for a BESS owner without theoretical skills in electrochemistry or lab procedures, and not requiring the ability to disassemble the BESS in order to test each individual component. The BESS model developed is characterized by an experimental campaign. The test procedure itself is framed in the context of this study and adopted for the experimental campaign on a commercial large-scale BESS. Once the model is characterized by the experimental parameters, it undergoes the verification and validation process by testing its accuracy in simulating the provision of frequency regulation. A case study is presented for the sake of presenting a potential application of the model. The procedure developed and validated is replicable in any other facility, due to the low complexity of the proposed experimental set. This could help stakeholders to accurately simulate several layouts of network services.

show abstract

Li-NMC Batteries Model Evaluation with Experimental Data for Electric Vehicle Application

Cited by 22 publications

References 12 publications

Characterization of NMC Lithium-ion Battery Degradation for Improved Online State Estimation

Characterization of NMC Lithium-ion Battery Degradation for Improved Online State Estimation

A Comparative Study on the Parameter Identification of an Equivalent Circuit Model for an Li-ion Battery Based on Different Discharge Tests

Modeling a Large-Scale Battery Energy Storage System for Power Grid Application Analysis

Contact Info

Product

Resources

About