Title: NARX modelling of a lithium iron phosphate battery used for electrified vehicle simulation

Authors: Xiao-song Hu; Feng-chun Sun; Sheng-bo Li; Ya-lian Yang

Addresses: National Engineering Laboratory for Electric Vehicles, Beijing Institute of Technology, Beijing 100081, China ' National Engineering Laboratory for Electric Vehicles, Beijing Institute of Technology, Beijing 100081, China ' State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084, China ' State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China

Abstract: Non-linear autoregressive exogenous (NARX) black-box modelling methodology is presented to model a lithium iron phosphate battery for system-level electrified vehicle simulation. The NARX model regressor vector is carefully chosen for dynamically representing the battery voltage and its dependence on state of charge (SOC) and charging/discharging current. Three types of non-linearity estimators, i.e., wavelet network, one-layer sigmoid network, and binary tree partition, are investigated and compared. The prediction error minimisation by means of the advanced adaptive Gaussian-Newton search algorithm is applied to implement the model parameterisation. The impact of the number of basis function units on the model accuracy and complexity is also studied. A preferred NARX model is determined, according to a comprehensive evaluation of model accuracies in two different datasets and complexity. A comparison between the preferred NARX model and a conventionally statically non-linear black-box battery model is made.

Keywords: battery modelling; NARX model; lithium iron phosphate batteries; electric vehicles; simulation; nonlinear estimators; wavelet networks; sigmoid networks; binary tree partition; model parameterisation.

DOI: 10.1504/IJMIC.2013.056191

International Journal of Modelling, Identification and Control, 2013 Vol.20 No.2, pp.181 - 189

Published online: 27 Sep 2014 *

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