Traction Battery Capacity Estimation Using Low-Uncertainty SOC Data
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Solution Overview
Problem
Existing battery capacity estimation methods in electric vehicles suffer from significant uncertainties due to inherent inaccuracies in state of charge (SOC) measurements and amp-hour throughput calculations, leading to unreliable battery capacity assessments.
Innovation Solution
A method and system that selectively uses battery data points with minimum uncertainties by comparing and selecting time periods with the lowest SOC difference uncertainties, thereby refining battery capacity estimation and reducing uncertainties in capacity calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If battery capacity estimation uses all available battery data points, then more data is utilized for estimation, but the uncertainty in capacity estimation increases due to inclusion of data with high SOC measurement errors
Solution Approach 1:
The patent segments the battery data points into multiple groups based on their associated SOC uncertainty levels. Instead of treating all data points uniformly, the system divides them into segments (e.g., high uncertainty, medium uncertainty, low uncertainty groups) and selectively uses segments with lower uncertainty for capacity estimation. This segmentation allows the system to utilize sufficient data points while maintaining estimation accuracy by excluding problematic high-uncertainty data.
Solution Approach 2:
The patent applies local quality by assigning different weights or selection criteria to different data points based on their local uncertainty characteristics. Data points with low SOC measurement uncertainty are selected or weighted more heavily, while data points with high uncertainty are excluded or weighted less. This local differentiation in data quality assessment enables precise capacity estimation by focusing on reliable data regions.
2Duration of action of moving object
If battery capacity estimation uses data from all time periods, then comprehensive battery behavior is captured, but the reliability of capacity assessment decreases due to varying SOC measurement accuracies across different operating conditions
Solution Approach 1:
The patent implements a dynamic data selection approach where the set of usable battery data points changes based on real-time or historical SOC uncertainty assessments. Rather than using a fixed time window or all available data uniformly, the system dynamically identifies and selects data points from various time periods that meet uncertainty criteria. This dynamic selection maintains comprehensive time period coverage while ensuring reliability by adapting to varying measurement conditions.
Solution Approach 2:
The patent changes the selection parameter from simple time-based inclusion to uncertainty-based filtering. By introducing SOC uncertainty as a critical selection parameter, the system transforms how data from different time periods is evaluated. Data points are included or excluded based on their uncertainty parameter values rather than solely on their temporal position, enabling reliable capacity assessment across comprehensive time periods.
3Productivity
If traditional battery capacity estimation methods are used, then the estimation process is simple and fast, but the accuracy of capacity estimation is insufficient due to inherent SOC measurement inaccuracies
Solution Approach 1:
The patent applies preliminary action by pre-assessing and storing SOC uncertainty values for different battery data points before the capacity estimation process. This preliminary uncertainty characterization allows the estimation algorithm to quickly filter and select appropriate data points without performing complex real-time uncertainty analysis during the estimation itself. The preprocessing step maintains fast processing speed while enabling accurate uncertainty-based data selection.
Solution Approach 2:
The patent incorporates feedback mechanisms where SOC uncertainty measurements from previous operations inform the selection of data points for subsequent capacity estimations. The system uses feedback from SOC measurement quality assessments to adjust which data points are included in the estimation, creating a closed-loop process that continuously improves accuracy while maintaining efficient processing through learned patterns in uncertainty behavior.
Data Source
AI summary
An automotive power adjusts a maximum discharge power of a traction battery according to an estimated capacity. The estimate capacity depends on data of the traction battery from instances of time selected based on a delta state of charge uncertainty associated with the instances of time. The automotive power system may further store the data.


