Battery Module Current Control for Cell Resistance Imbalance
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Solution Overview
Problem
In battery systems, inconsistent internal resistances among cells lead to uneven current distribution during charging and discharging, potentially causing overcharging and reducing battery lifespan and safety.
Innovation Solution
A battery control method and apparatus that adjusts the current through each battery cell to ensure it remains within a safe range by identifying the module with the largest resistance difference and controlling the charging or discharging current accordingly, using resistance values and state of charge data to determine safe current limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If battery cells with inconsistent internal resistances are connected in parallel to increase battery capacity, then the battery capacity increases, but the current distribution becomes uneven leading to overcharging and reduced safety
Solution Approach 1:
The patent measures the internal resistance of each battery cell before charging/discharging operations and pre-calculates the safe current limit based on the cell with the largest resistance difference in parallel modules. This preliminary assessment prevents overcharging by establishing safe operating parameters before the charging process begins.
Solution Approach 2:
The patent implements a feedback mechanism where the control device continuously monitors the actual charging current and compares it against the pre-calculated safe current limit. Based on this feedback, the charging current is dynamically adjusted to ensure it does not exceed the safe threshold, thereby preventing overcharging and maintaining battery safety.
2Speed
If fast charging is applied to battery cells with inconsistent internal resistances, then charging speed increases, but the branch current exceeds the limiting value causing overcharging
Solution Approach 1:
The patent dynamically adjusts the charging current based on real-time measurements of internal resistance and state of charge. The safe current limit is not fixed but is continuously updated according to the actual battery conditions, allowing the system to optimize charging speed while preventing overcharging through adaptive current control.
Solution Approach 2:
The patent changes the charging current parameter dynamically during the charging process. By measuring internal resistance at different states and adjusting the charging current accordingly, the system maintains optimal charging speed while ensuring the current never exceeds the safe threshold determined by the cell with the largest resistance difference.
Data Source
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AI summary
Embodiments of this application disclose a battery control method. The method in the embodiments of this application includes: detecting whether current value of N battery modules is greater than a safe current, where the safe current is a safe current of a target battery module, and the target battery module is a battery module that has a largest resistance difference of parallel branch circuits respectively corresponding to M battery cells in a same battery module; and when a current value of at least one of the N battery modules is greater than the safe current, adjusting the current value of the N battery modules, so that the current value respectively corresponding to the N battery modules is equal to or less than the safe current. This application is used to control a current that passes through a battery to be less than or equal to a safe current corresponding to a battery module that has a largest resistance difference of parallel branch circuits respectively corresponding to battery cells in a same battery module, so that a charging current or a discharging current of each battery cell in the battery module is within a safe current range. This improves safety performance and a lifespan of the battery.