Online Impedance Measurement Method for Large‐Capacity Batteries Based on Reconfigurable Battery Module

ABSTRACT Electrochemical impedance spectroscopy (EIS) is a nonintrusive detection technique that is extensively utilized in battery state estimation and fault diagnosis. This paper addresses the challenge of online impedance measurement for large‐capacity cells by employing reconfigurable battery modules to perform such measurements. Given that existing EIS measurement signal forms and design methods are not directly applicable to the impedance measurement of large‐capacity cells and have poor measurement results, this study proposes a time‐optimized multisine group pulse‐width modulation (TO‐MSGPWM). Under the premise of meeting the excitation signal limitations required for online impedance measurement of large‐capacity cells, this approach aims to retain as many advantages of traditional multisine pulse‐width modulation (MSPWM) signals as possible while reducing the total signal duration. A commercial reconfigurable battery module prototype consisting of 16,280 Ah lithium‐ion cells is constructed to validate the feasibility of the proposed excitation signal. The experimental results demonstrate the superiority of the proposed excitation signals compared to traditional MSPWM and Discrete Interval Binary Sequence (DIBS) signals.