Estimating power capability of aged lithium-ion batteries in presence of communication delays
Journal article, 2018

Efficient control of electrified powertrains requires accurate estimation of the power capability of the battery for the next few seconds into the future. When implemented in a vehicle, the power estimation is part of a control loop that may contain several networked controllers which introduces time delays that may jeopardize stability. In this article, we present and evaluate an adaptive power estimation method that robustly can handle uncertain health status and time delays. A theoretical analysis shows that stability of the closed loop system can be lost if the resistance of the model is under-estimated. Stability can, however, be restored by filtering the estimated power at the expense of slightly reduced bandwidth of the signal. The adaptive algorithm is experimentally validated in lab tests using an aged lithium-ion cell subject to a high power load profile in temperatures from −20 to +25 °C. The upper voltage limit was set to 4.15 V and the lower voltage limit to 2.6 V, where significant non-linearities are occurring and the validity of the model is limited. After an initial transient when the model parameters are adapted, the prediction accuracy is within ±2% of the actually available power.

Lithium-ion

Time-delay systems

State of power

Power capability

Adaptive estimation

Battery management

Author

Björn Fridholm

Volvo Cars

Torsten Wik

Chalmers, Electrical Engineering, Systems and control, Automatic Control

H. Kuusisto

Volvo Cars

Anton Klintberg

Chalmers, Electrical Engineering, Systems and control, Automatic Control

Journal of Power Sources

0378-7753 (ISSN)

Vol. 383 24-33

Subject Categories

Control Engineering

Signal Processing

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1016/j.jpowsour.2018.02.018

More information

Latest update

4/18/2018