Battery Cell Self-Discharge Monitoring for Pack Balancing
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Solution Overview
Problem
Existing battery management systems fail to monitor and manage inconsistent self-discharge rates of individual cells in a power battery pack during use, leading to uneven charging and discharging, which affects the overall capacity and performance of the battery pack.
Innovation Solution
A battery management method and apparatus that calculates a target equivalent self-discharge value for each cell by analyzing the high-voltage inflection point power values and historical cumulative balance power values, allowing for the identification and management of cells with abnormal self-discharge rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-discharge detection is performed only before leaving the factory, then initial cell selection can be made, but self-discharge cannot be monitored during use and aging
Solution Approach 1:
The patent performs preliminary self-discharge detection before leaving the factory to select cells with similar self-discharge rates for assembly. This preliminary action establishes a baseline that enables subsequent monitoring of changes during use and aging, resolving the contradiction by having detection done both before assembly and during operation.
2Productivity
If cells with different self-discharge rates are assembled into the power battery pack, then production efficiency is maintained, but inconsistent states of charge occur and capacity is affected
Solution Approach 1:
The patent changes the parameter being monitored from static factory-test self-discharge rates to dynamic during-use self-discharge rates. By continuously monitoring self-discharge during operation and identifying cells whose rates diverge from the pack average, the system can detect and manage cells that are deviating from optimal performance, thereby maintaining battery pack capacity despite initial production efficiency considerations.
3Manufacturing precision
If self-discharge rates are matched during assembly, then initial consistency is achieved, but aging causes rates to change and inconsistency develops
Solution Approach 1:
The patent implements feedback by continuously monitoring the self-discharge rates of cells during use and comparing them to the average self-discharge rate of the battery pack. When a cell's self-discharge rate deviates beyond a threshold from the average, the system identifies this cell and can take corrective actions such as adjusting charging strategies or replacing the cell, thereby maintaining consistency despite aging effects.
Data Source
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AI summary
Provided is a battery management method, including: obtaining a current high-voltage inflection point power value of each cell; obtaining a current historical cumulative balance power value of each cell (S 102); obtaining a current equivalent self-discharge value of each cell through calculation (S103); obtaining an equivalent self-discharge value at a previous moment of each cell (S 104); obtaining a target equivalent self-discharge value of each cell through calculation (S 105); determining a maximum target equivalent self-discharge value and a minimum target equivalent self-discharge value (S 106); obtaining a maximum equivalent self-discharge rate and a minimum equivalent self-discharge rate through calculation (S 107); and when a difference between the maximum equivalent self-discharge rate and the minimum equivalent self-discharge rate is greater than a preset threshold, managing a target cell corresponding to the maximum target equivalent self-discharge value (S108). The present invention further provides a battery management apparatus, a vehicle, and a computer-readable storage medium.