Battery Full Charge Capacity Estimation Using Deterioration Models
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Solution Overview
Problem
Existing methods for estimating battery full charge capacity are inaccurate and dependent on significant changes in the charged state, leading to potential deviations over time, especially in electric vehicles.
Innovation Solution
A method involving a battery management system that utilizes a capacity deterioration model to estimate full charge capacity based on preset information, combined with discharge current integration and weighted averaging, using sensors to acquire real-time data and adjust estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If estimation is based on discharge current integration and charged state change, then estimation accuracy improves when charged state change is large, but estimation accuracy deteriorates when charged state change is small
Solution Approach 1:
The patent changes the estimation parameters by introducing a capacity deterioration model that uses preset battery information (initial capacity, impedance, cycle count, temperature) as input parameters. This allows the system to estimate full charge capacity accurately regardless of the charged state change degree, as the model compensates for small changes by relying on the predetermined relationship between preset information and capacity deterioration
Solution Approach 2:
The patent performs preliminary action by pre-establishing the capacity deterioration model with predetermined relationships between battery preset information and capacity deterioration amounts. This preliminary modeling allows the system to directly estimate full charge capacity without requiring large charged state changes during operation, as the estimation logic is prepared in advance
2Measurement precision
If estimation relies on significant charged state change, then estimation accuracy improves, but estimation reliability deteriorates over time as battery operates
Solution Approach 1:
The patent implements feedback by continuously updating the full charge capacity estimation using the capacity deterioration model that incorporates battery cycle count, temperature history, and impedance changes. The model continuously adjusts estimates based on accumulated operational data, maintaining reliability over the battery lifecycle without requiring periodic large charged state changes
Solution Approach 2:
The patent establishes preliminary action through the capacity deterioration model that predetermines the relationship between battery operating conditions and capacity loss. This pre-established model provides consistent estimation reliability over time by relying on the predetermined deterioration pattern rather than requiring repeated calibration through large charged state changes
Data Source
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AI summary
In a battery system 100 managed by a control unit 20 (a battery management system), a first estimation portion 46 estimates an estimated value H1, based on a value acquired by an acquisition portion 42 and a capacity deterioration model DM1. The acquisition portion 42 acquires information including a voltage value, a temperature value, and a current value. The capacity deterioration model DM1 is a model related to preset information and a capacity deterioration amount of a battery 1. The estimated value H1 is estimated, for example, when an ignition of an electric vehicle is turned on.