Title: SOC estimation algorithm for Li-ion battery in electric or hybrid vehicles

Authors: Chuanxin Wang

Addresses: College of Automation, Chongqing University, Chongqing, 400044, China

Abstract: As over-charging and over-discharging can cause damage to batteries, to guarantee the stability and duration of batteries, it is necessary to avoid being over-charged and over-discharged. Therefore, knowing the batteries' state of charge (SOC) is essential. In this paper, the author describes in detail the procedure of building a SOC estimation algorithm. The SOC estimation algorithm is based on unscented Kalman filter. Moreover, changes of battery capacity and internal resistance are considered. The impact of these changes on the estimation accuracy is explored. Experiments on an Iron Phosphate Li-ion battery cell with real load were conducted to justify this method. This method was verified to be not only precise but also stable.

Keywords: SOC estimation; state of charge; Kalman filtering; unscented Kalman filter; iron phosphate Li-ion batteries; hybrid electric vehicles; hybrid vehicles; lithium-ion batteries; battery over-charging; battery over-discharging; battery lifetime; battery capacity; internal resistance.

DOI: 10.1504/IJEHV.2016.076962

International Journal of Electric and Hybrid Vehicles, 2016 Vol.8 No.1, pp.61 - 77

Received: 08 Jun 2015
Accepted: 07 Dec 2015

Published online: 08 Jun 2016 *

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