Battery OCV Correction for Accurate Full Charge Capacity Estimation
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Solution Overview
Problem
Existing methods for correcting the full charge capacity of secondary batteries, such as the 2-point OCV correction method, suffer from inaccuracies due to changes in RSOC-OCV characteristics over time, leading to significant variations in calculated full charge capacity.
Innovation Solution
A control device for secondary batteries that corrects battery characteristics by acquiring multiple open circuit voltage data points during charging, weighting and averaging the corrections between data pairs to improve the accuracy of full charge capacity calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If 2-point OCV correction method is used, then correction process is simple, but measurement precision of full charge capacity deteriorates due to variations in RSOC-OCV characteristics
Solution Approach 1:
The patent segments the OCV correction process by dividing the battery charge/discharge cycle into multiple measurement points rather than using only 2 points. Multiple OCV values are acquired at different remaining capacity levels during charging, and corrections are performed for multiple data pairs to reduce the impact of RSOC-OCV characteristic variations.
Solution Approach 2:
The patent applies partial correction by selectively correcting only certain OCV data pairs based on their remaining capacity ranges. Corrections are performed for data pairs where the remaining capacity difference falls within specific ranges (e.g., 5-50% or 50-95%), avoiding correction of all data points while still improving measurement precision.
2Measurement precision
If multiple OCV data points are acquired and corrected, then measurement precision of full charge capacity improves, but device complexity increases
Solution Approach 1:
The patent performs correction operations selectively on partial sets of OCV data pairs rather than processing all possible combinations. By limiting corrections to data pairs with specific remaining capacity differences, the computational complexity is reduced while still achieving improved measurement precision through multiple measurements.
Solution Approach 2:
The patent segments the correction process into multiple stages: acquiring OCV data at multiple points, selecting appropriate data pairs based on remaining capacity ranges, performing corrections on selected pairs, and averaging results. This segmentation makes the complex process more manageable and systematic.
Data Source
AI summary
The present disclosure provides a control device for a secondary battery, and the control device includes a controller configured to correct battery characteristics on an open circuit voltage to a remaining capacity of the secondary battery. In the control device for the secondary battery, the controller acquires data of a plurality of open circuit voltages in the battery characteristics during charging the secondary battery. When the secondary battery is fully charged, the controller corrects the open circuit voltages between respective pairs selected and combined from at least one part of the data of the plurality of open circuit voltages. The controller weighted-averages and corrects full charge capacities, which are calculated by the correction of the open circuit voltages between the respective data pairs, with differences each between respective remaining capacities each corresponding between the respective data pairs.