State of Charge Estimation of Lithium-ion Battery in Electric Vehicles Using the Smooth Variable Structure Filter: Robustness Evaluation against Noise and Parameters Uncertainties

Abstract

State of Charge (SoC) of Lithium-ion battery is a key parameter in battery management systems for electric vehicles. This paper uses the fundamental theory of the smooth variable structure filter (SVSF) and proposes a SoC estimation algorithm for a Manganese Cobalt (NMC) cell with a nominal capacity of 20 Ah. Several tests are conducted considering different types of noise and parameters variation. A nonrandom Gaussian noise is first added to the battery voltage. The maximum root mean square error (RMSE) of the estimated SoC is about $2.8\%$ for a standard deviation of the noise set to $2.6e^{-3}$ P.U. The same noise is applied to the battery current and the maximum RMSE of the SoC is obtained as 1.36%. Moreover, an EMI noise is added to the battery voltage and the obtained RMSE of the SoC is about 1.73% for a peak amplitude of the noise set to 0.07 P.U. The convergence of the algorithm is also confirmed under battery parameters variation due to the temperature change. However, its accuracy degrades considerably. Finally, a comparative study is carried out with the extended Kalman filter and shows the superiority of SVSF in terms of accuracy and robustness against measurement noise.

Keywords:

• Li-ion battery
• state of charge
• battery management system
• electric vehicle
• smooth variable structure filter
• electromagnetic interference

Acknowledgments

The authors acknowledge the research laboratory of advanced technology and intelligent systems (LATIS), and the university of Sousse for supporting this work. No relevant financial or non-financial competing interests to report.

Additional information

Notes on contributors

Meriem Ben Lazreg

Meriem Ben Lazreg Received the electrical engineering degree in 2015 from the National engineering school of Monastir, Tunisia. In 2017, she received her M.S degree in Information treatment and complexity living from the National engineering school of Tunis, Tunisia, it is a double degree with Paris Descartes university, France. She is currently working toward her Ph.D. degree in electrical engineering, in the research laboratory LATIS, National Engineering School of Sousse, University of Sousse, Tunisia. She is also currently working as electrochemical engineer of automotive battery as a Peugeot-Citroën partners. Her research focuses on battery monitoring system for electrical vehicle application.

Ines Baccouche

Ines Baccouche Received the engineering degree in Applied Computer Science, the M.S degree in Intelligent and Communication Systems, from the National Engineering School of Sousse(ENISo), Tunisia in 2010, 2012 respectively. In 2018, she received a Ph.D. degree in Electrical Engineering from the university of Monastir, Tunisia. Since 2016, she has been an assistant professor at ENISo in embedded electronic systems. She is actually a research member of the Laboratory of Advanced Technology and Intelligent Systems-LATIS, Tunisia. Her current research interests include the fields of energy systems modeling and controlling, energy harvesting and battery management systems.

Sabeur Jemmali

Sabeur Jemmali Received the engineering degree (1999) from the National Engineering School of Sfax – Sfax University (Tunisia), a MS degree (2000) in Electronic and a Ph.D degree (2003) in Electronic and Communication from Telecom Paris Tech (France). He is now Associate Professor in Microelectronic, Electronic, and Embedded System at the National Engineering School of Sousse – Sousse University (Tunisia). He is a Founding member of the LATIS research labs (Laboratory of Advanced Technology and Intelligent Systems). He directed the studies department at the National Engineering School of Sousse (From October 2011 to July 2014). His research interests are microelectronic, electronic, embedded systems and systems modeling (modeling of electronic components, memories modeling, batteries modeling, etc.).

Bilal Manai

Bilal Manai Received the M.S and Ph.D in Microelectronic, Electronic and Communication from Telecom Paris Tech in 1998 and 2002, respectively. He is a serial entrepreneur. In the last 10 years, he founded and co-founded Yaslamen, IntelliBatteries, Recytex, and Yedess. Before his entrepreneurial experience, he worked 3 years as research engineer in Wavecom a French startup acquired by Sierra Telecom the leader in M2M managed solutions. He worked for 6 years as R&D engineer then as a project manager in Atmel Corp. He occupied the position of chief executive officer for 5 years of Yaslamen a startup specialized in smart battery management solutions. He also has an academic experience as a Professor. He taught Microelectronic, electronic and energy respectively at PolyTech Montpellier, PolyTech Marseille and Ecole des Mines de Saint Etienne from 2002 until 2014. He holds 4 US and 3 French Patents and published several scientific papers. Since 2017 he joined the Department of Electrical Engineer of Cégep de l’Outaouais in Québec, Canada where he is a full professor. His research interests include electric power components and systems.

Mahmoud Hamouda

Mahmoud Hamouda Received his B.S., Agregation, M.S., and Ph.D. degrees, all in electrical engineering, from ENSET and the Ecole Superieure des Sciences et Techniques, University of Tunis, Tunisia, in 1995, 1996, 2004, and 2010, respectively. He received the HDR from the University of Sousse in 2017. He is currently a Professor of electrical engineering with ISSAT at the University of Sousse, Tunisia. He is affiliated with Canada Research Chair in Electric Energy Conversion and Power Electronics, Ecole de Technologie Supérieure in Montreal, Canada. He is also a member of the research laboratory LATIS, National Engineering School of Sousse, University of Sousse, Tunisia. His main research interests include renewable energy conversion systems, digital signal processor, and field-programmable gate array for embedded real-time control, grid-connected converters, and fault diagnosis of power converters.