SOC Estimation of a Rechargeable Li-Ion Battery Used in Fuel Cell Hybrid Electric Vehicles—Comparative Study of Accuracy and Robustness Performance Based on Statistical Criteria. Part II: SOC Estimators

Sorin-Mihai Radu,Nicolae Tudoroiu,Mohammed Zaheeruddin,Roxana-Elena Tudoroiu

doi:10.3390/batteries6030041

Sorin-Mihai Radu, Nicolae Tudoroiu + Show 2 more

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https://doi.org/10.3390/batteries6030041

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Abstract

The purpose of this paper is to analyze the accuracy of three state of charge (SOC) estimators of a rechargeable Li-ion SAFT battery based on two accurate Li-ion battery models, namely a linear RC equivalent electrical circuit (ECM) and a nonlinear Simscape generic model, developed in Part 1. The battery SOC of both Li-ion battery models is estimated using a linearized adaptive extended Kalman filter (AEKF), a nonlinear adaptive unscented Kalman filter (AUKF) and a nonlinear and non-Gaussian particle filter estimator (PFE). The result of MATLAB simulations shows the efficiency of all three SOC estimators, especially AEKF, followed in order of decreasing performance by AUKF and PFE. Besides, this result reveals a slight superiority of the SOC estimation accuracy when using the Simscape model for SOC estimator design. Overall, the performance of all three SOC estimators in terms of accuracy, convergence of response speed and robustness is excellent and is comparable to state of the art SOC estimation methods.

Highlights

The MATLAB simulation results are shown in Appendix A.1, and the statistical criteria values are given in Appendix A.2, Table A3
The MATLAB simulation results are depicted in the main part of the manuscript and in Appendix A.1, and the statistical criteria values are given in Appendix A.2, Table A4
The MATLAB simulation results for the first scenario are presented in Appendix A.1, Figure A13a–c, and the statistical criteria values are given in Appendix A.2, Table A1

Summary

Introduction

The lithium-ion battery has proven to be an ideal safety battery for hybrid electric vehicles, with high discharge power, environmental protection, low pollution, and long life [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19].Some details about its features, modelling, and hybrid combinations with different power sources in a fuel cell electric vehicle (FCEV) and power distribution controlled and optimized by an energy management system (EMS) are shown in Part 1 [20]. The lithium-ion battery has proven to be an ideal safety battery for hybrid electric vehicles, with high discharge power, environmental protection, low pollution, and long life [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]. The Li-ion battery as a direct energy supply and its SOC have a significant impact on the HEV’s performance. Batteries 2020, 6, 41 accurate estimate of the SOC has an important theoretical significance and application value [1,2,5,6]. In the absence of a measurement sensor, the SOC cannot be measured directly; its estimation using a Kalman filter technique is required [5]

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Results

Conclusion