Battery Cell Balancing by Charge Capacity Tracking
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Solution Overview
Problem
Conventional cell balancing methods in battery modules suffer from slow balancing speed, erroneous balancing, and short balancing time, leading to rapid capacity fading, increased internal resistance, and reduced available capacity due to cell inconsistency.
Innovation Solution
A cell balancing device and method that determines balancing capacity based on the charge capacity of cells with voltages greater than or equal to the minimum cell voltage, updating balancing capacity during charging and static conditions, and performing balancing operations when specific conditions are met to enhance accuracy and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional balancing is activated only at the end of charging stage or static standing stage based on instantaneous voltage difference, then device complexity is reduced and ease of operation is improved, but balancing speed becomes slow and balancing time is limited
Solution Approach 1:
The patent transforms the static balancing approach (activated only at specific stages) into a dynamic balancing approach that continuously monitors charge capacity and activates balancing based on real-time cell voltage differences during charging operations. This enables balancing to occur at any moment when voltage difference exceeds the threshold, significantly improving balancing speed without requiring complex additional hardware.
Solution Approach 2:
The patent implements a feedback mechanism that continuously monitors the charge capacity of each cell and the voltage difference between cells during charging operations. When the voltage difference exceeds a predetermined threshold, the system provides feedback to activate balancing for cells with higher charge capacity, creating a closed-loop control system that improves balancing speed and accuracy.
2Measurement precision
If instantaneous voltage difference is used as the basis for determining balancing activation, then measurement simplicity is improved, but measurement precision deteriorates leading to erroneous balancing
Solution Approach 1:
The patent introduces charge capacity as an intermediary parameter between instantaneous voltage measurement and balancing activation decision. Instead of directly using voltage difference, the system integrates current over time to calculate charge capacity, which serves as a more reliable indicator of actual cell state and reduces erroneous balancing while maintaining measurement simplicity.
Solution Approach 2:
The patent changes the measurement parameter from instantaneous voltage difference to charge capacity (integrated current over time). This parameter transformation provides a more accurate representation of cell state and balancing needs, improving measurement precision and reducing erroneous balancing activation while the system continues to use simple current integration for calculation.
3Productivity
If balancing is performed based on voltage difference threshold at limited time points, then ease of operation is improved, but productivity deteriorates due to reduced balancing time and frequency
Solution Approach 1:
The patent implements continuous monitoring of charge capacity and voltage difference during the entire charging operation, allowing balancing to be activated at any moment when the voltage difference threshold is exceeded. This continuous action approach maximizes balancing opportunities and time, significantly improving balancing efficiency and productivity while maintaining operational simplicity through automated threshold-based control.
Data Source
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AI summary
This application discloses a cell balancing device and method. The method includes: obtaining a first minimum cell voltage value and a first maximum cell voltage value of a to-be-balanced battery module in a latest full-charging operation; determining a first charge capacity of a first target cell in the battery module in a corresponding first time period in response to a first charging operation performed by the battery module; and updating a balancing capacity of the first target cell based on the first charge capacity. The first target cell is a cell with a voltage value greater than or equal to the first minimum cell voltage value. The first time period corresponding to the first target cell is a period of time that begins when the voltage value of the first target cell reaches the first minimum cell voltage value for a first time and that ends when the first charging operation of the battery module is ended.