Lithium-ion Battery SoC Estimation of an Order-reduced Electrochemical Model Using SMO-URL in EVs
Abstract
To estimate lithium-ion battery SoC accurately, a lithium-ion battery electrochemical model is adopted in this paper. Firstly, the electrochemical model is reasonable order-reduced to an average-electrode model (AEM). Secondly, sliding-mode observer (SMO) with a uniform reaching law (URL) combined with AEM is developed to estimate SoC of lithium-ion cell from external measured voltage and current value. An estimation scheme is designed. The observer estimates the SoC by using lithium-ion solid-electrolyte concentration. To demonstrate the performance of the proposed scheme, the simulations are verified by experiments from a 2.3Ah high-power LiFePO4/graphite cell used in electric vehicles (EVs). The results show that the proposed estimation scheme with the SMO-URL algorithm performs well with initial error values. The maximum SoC estimation errors are less than 2% under Hybrid Pulse Power Characteristic (HPPC) Test.
Keywords
State-of-Charge (SoC), electrochemical model, sliding mode observers (SMO), algorithm
DOI
10.12783/dteees/iceee2018/27795
10.12783/dteees/iceee2018/27795
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