State Estimation of Lithium Ion Battery Based on Electrochemical Impedance Spectroscopy with On-Board Impedance Measurement System

Lithium ion battery is widely used in electric vehicles. To estimate battery state-of-charge, state-of-health and internal temperature accurately is not only in laboratory but also on-board significant. As a useful tool to study electrochemical system, numbers of estimation methods based on electrochemical impedance spectroscopy arise. The paper focuses on the relation between the battery states and impedance to develop a decoupled state estimation method to satisfy on-board applications. To overcome shortcomings of bulky and high cost of electrochemical impedance spectroscopy equipment in laboratory, an impedance measurement system is designed. Validation results indicate that the battery states can be estimated properly with the impedance based method and the developed measurement system works well, which facilitates the implementation of the impedance based state estimation on board.