Battery Condition Estimation via Voltage Inflection Points
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Solution Overview
Problem
Existing methods for estimating the condition of electric storage devices require charging or discharging them until they reach a fully charged or fully discharged state, which is time-consuming and limits frequent condition estimation.
Innovation Solution
A condition estimation device that detects distinctive points in voltage variation per unit remaining capacity or unit time during charge or discharge, allowing for condition estimation without reaching full charge or discharge states, using a controller to estimate capacity and internal resistance based on these points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electric storage device is charged or discharged until it reaches a fully charged or fully discharged state for condition estimation, then the measurement precision of battery capacity is improved, but the time required for condition estimation increases
Solution Approach 1:
The patent extracts the essential information needed for accurate battery capacity measurement from the complete charge-discharge cycle. By identifying and utilizing distinctive points (inflection points) in the voltage-time curve that occur during partial charging/discharging, the method extracts sufficient diagnostic information without requiring the full cycle to complete, thus reducing time while maintaining measurement precision
Solution Approach 2:
The patent applies partial action by performing condition estimation using only a portion of the charge-discharge cycle rather than the complete cycle to full charge/discharge. The distinctive points method requires only monitoring voltage changes during a limited charge/discharge interval, which is less than the full cycle, thereby reducing the time investment while still providing accurate capacity estimation
2Reliability
If the electric storage device is charged or discharged until it reaches a fully charged or fully discharged state for condition estimation, then the reliability of condition data is improved, but the frequency of condition estimation decreases
Solution Approach 1:
The method extracts reliable condition data from specific distinctive points in the voltage-time curve that occur during partial charging/discharging. These inflection points contain sufficient information about battery capacity and health, allowing reliable estimation without requiring the time-consuming full charge-discharge cycles that would limit estimation frequency
Solution Approach 2:
The patent performs preliminary identification of distinctive points during the charge-discharge process before complete charging or discharging occurs. By detecting inflection points in real-time during the process, the system can estimate battery condition at multiple intervals throughout operation, increasing frequency while maintaining reliability through the use of these predetermined characteristic points
3Measurement precision
If the electric storage device is charged or discharged until it reaches a fully charged or fully discharged state for condition estimation, then the accuracy of capacity measurement is improved, but the complexity of the estimation process increases
Solution Approach 1:
The patent replaces the mechanical complexity of complete charge-discharge cycling with a computational approach. By using mathematical detection of distinctive points (inflection points) in the voltage-time curve and applying calculation formulas based on these points, the system achieves accurate capacity measurement through data processing rather than through the complex procedural steps of managing full charge-discharge cycles
Solution Approach 2:
The patent changes the measurement parameter from requiring complete charge-discharge cycle completion to monitoring voltage-time characteristics during partial cycling. By focusing on the temporal and voltage parameters at distinctive points rather than the absolute charge state, the method simplifies the estimation process while maintaining measurement accuracy through parameter-based calculation
Data Source
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AI summary
A condition estimation device for estimating condition of an electric storage device includes a voltage detector and a controller. A voltage measurement circuit (24) as the voltage detector is configured to detect a voltage (V) of a secondary battery (14) as the electric storage device. A BM (62) as the controller is configured to perform a distinctive point detection process to detect a distinctive point (P) based on the voltage (V) detected by the voltage measurement circuit (24), and an estimation process to estimate the condition of the secondary battery (14) (e.g., a battery capacity (X)) based on the distinctive point (P) detected in the distinctive point detection process. The distinctive point (P) is a point at which a variation in voltage per unit remaining capacity or per unit time (ΔV) of the secondary battery (14) during charge or discharge is a local maximum value. In this configuration, the condition of the secondary battery (14) (e.g., the battery capacity (X)) can be estimated without charging or discharging the secondary battery (14) until the secondary battery (14) satisfies a predetermined fully charged condition or fully discharged condition.