Title: Self-organising map based classification of LiFePO₄ cells for battery pack in EVs

Authors: Fengxian He; W.X. Shen; Qiang Song; Ajay Kapoor; Damon Honnery; Daya Dayawansa

Addresses: Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria, 3122, Australia ' Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria, 3122, Australia ' National Engineering Laboratory for Electric Vehicles, Beijing Institute of Technology, Beijing 100008, China ' Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria, 3122, Australia ' Department of Mechanical and Aerospace Engineering, Monash University, Clayton, Victoria 3800, Australia ' Department of Mechanical and Aerospace Engineering, Monash University, Clayton, Victoria 3800, Australia

Abstract: This paper presents a self-organising map (SOM) based classification of lithium iron phosphate cells for a battery pack in EVs. The experimental data of the cells have been obtained to train the SOM. The temperature variation, internal resistance and available capacity of the cells are used as the inputs of the SOM, and the output of the SOM classifies the cells into three groups with the similar characteristics in terms of its input parameters. Then, the cells in the same group are connected in series to build a sorted battery pack whereas the randomly chosen cells are connected in series to build an unsorted battery pack. The comparison of the consistency between these two battery packs under different discharging conditions has demonstrated the effectiveness of the proposed classification method. In addition, the experimental results show that state of charge based approaches for cell balancing are more effective than voltage based approaches.

Keywords: lithium ion batteries; cell classification; battery packs; self-organising maps; SOM classification; electric vehicles; lithium iron phosphate cells; temperature variation; internal resistance; available capacity; state of charge; SoC; cell balancing.

DOI: 10.1504/IJVD.2015.073118

International Journal of Vehicle Design, 2015 Vol.69 No.1/2/3/4, pp.151 - 167

Received: 11 Oct 2014
Accepted: 04 Mar 2015
Published online: 20 Nov 2015 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article