Discharge Capacity Estimation for Lithium–Ion Battery Packs with Cells in Parallel Connection Based on Current Prediction of In‐Pack Cells

Abstract

Discharge capacity estimation for battery packs is one of the most essential issues of battery management systems. Precision of the estimation will affect maintenance policy and reliability estimation of the battery packs. Due to different manufacturing processes and use conditions, the performance of each cell in a battery pack may be significantly different. Such differences mean that a certain amount of capacity is not extracted from the in‐pack cells. For lithium‐ion battery packs with cells connected in parallel, a method is provided herein to predict the discharge current of the cells. Based on this method, an estimation of the discharge capacity of the pack can be obtained. An experiment is then conducted from which the cell current cannot be measured to validate the applicability of the method. The results show that the proposed method can be used to estimate the discharge capacity of battery packs with high accuracy. This method is significant for the grouping of lithium‐ion battery packs, as well as the maintenance and replacement policy of battery packs.

State‐of‐Charge Prediction of Lithium‐Ion Batteries Based on Sparse Autoencoder and Gated Recurrent Unit Neural Network

“…The state-of-charge (SOC), considered one of the crucial characteristics of the BMS, quantifies the remaining energy of a battery in the current cycle and indicates how long the battery can sustain before a recharge is required. [3,4] However, direct SOC measurement cannot be realized, and the SOC can only be inferred from measurable cell parameters, such as current and voltage.Due to its high importance, the battery SOC has been widely researched in recent years, and many methods for battery SOC prediction have been proposed. The opencircuit voltage (OCV) approach approximated the SOC based on the monotonic relationship between the SOC and its OCV.…”

“…The state-of-charge (SOC), considered one of the crucial characteristics of the BMS, quantifies the remaining energy of a battery in the current cycle and indicates how long the battery can sustain before a recharge is required. [3,4] However, direct SOC measurement cannot be realized, and the SOC can only be inferred from measurable cell parameters, such as current and voltage.…”