Battery Module SOC Control Using Ion Concentration Alignment
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Solution Overview
Problem
Existing methods for controlling battery modules of rechargeable batteries fail to accurately estimate the state of charge (SOC) due to varying deterioration states among battery cells, leading to potential overloading or underutilization of cells and difficulty in predicting full charge or discharge.
Innovation Solution
The method involves estimating the ion concentration rate of the active material in each battery cell, plotting this rate on a common axis, adjusting cell lengths based on reference values, and using this data to accurately determine the SOC of the battery module, thereby avoiding excessive loads and improving control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If battery module control is based solely on voltage of battery module or individual cells, then control simplicity is maintained, but SOC estimation accuracy deteriorates and cells may be overloaded or underutilized
Solution Approach 1:
The patent transforms the control approach by changing from direct voltage-based control to ion concentration rate-based control. By estimating ion concentration rates from voltage data and using these transformed parameters for SOC determination, the system achieves both operational simplicity and high accuracy. The ion concentration rate serves as an intermediate parameter that bridges simple voltage measurement and accurate SOC estimation.
2Device complexity
If battery module control does not account for varying deterioration states of individual cells, then control complexity is reduced, but reliability deteriorates due to potential overloading or underutilization of cells
Solution Approach 1:
The patent applies local quality by estimating ion concentration rates for each individual battery cell separately, accounting for their varying deterioration states. Each cell's ion concentration rate is determined based on its specific voltage characteristics, allowing the system to handle heterogeneous cell conditions. The final SOC is then derived from the collective ion concentration rates, ensuring reliable control that respects individual cell states.
3Speed
If voltage-based control is used without considering ion concentration dynamics, then real-time control responsiveness is improved, but measurement precision of SOC deteriorates
Solution Approach 1:
The patent introduces ion concentration rate as an intermediary parameter between voltage measurement and SOC determination. The ion concentration rate is estimated from voltage data in real-time and serves as a mediator that preserves the responsiveness of voltage-based control while achieving the precision of direct SOC measurement. This intermediary approach allows the system to maintain fast control response without sacrificing accuracy.
Data Source
AI summary
A method, executed by a control device, for controlling a battery module having battery cells includes: estimating an ion concentration rate of each battery cell; plotting the estimated ion concentration rate on a common axis, any battery cell serving as a reference battery cell, and a remaining battery cell serving as a non-reference battery cell; adjusting a length of the non-reference battery cell in accordance with the reference battery cell; shifting a position of the ion concentration rate of the non-reference battery cell on the axis to agree with that of the reference battery cell; and estimating an SOC of the battery module using a range between the ion concentration rate at a lowest upper limit voltage of the battery cells and the ion concentration rate at a highest lower limit voltage of the battery cells as an SOC range of 100% to 0% of the battery module.