Battery State of Charge Calculation Error Correction
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Solution Overview
Problem
Existing methods for determining the state of charge of a battery suffer from increasing deviations over time due to integral calculation errors, leading to inaccurate results, and lack precise reliability assessment for selecting the most accurate calculation method.
Innovation Solution
The method involves analyzing and comparing errors from different calculation methods for determining the state of charge, selecting the method with the smallest error to ensure accurate results, and adjusting the open-circuit voltage calculations accordingly, incorporating various dissipation factors and error estimations from idle phases and full charge conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the state of charge is calculated by integrating battery current over time, then the calculation is simple and can be performed continuously, but the deviation from actual state of charge increases steadily over time due to integral errors
Solution Approach 1:
The patent implements feedback by continuously comparing the calculated state of charge with measured values (such as open-circuit voltage-based SOC) and using this comparison to correct the calculated SOC. The system evaluates whether the calculated SOC deviates from expected values and adjusts accordingly, preventing error accumulation over time while maintaining continuous calculation capability.
2Measurement precision
If multiple calculation methods are used to determine state of charge, then accuracy is improved by selecting the more reliable calculation, but the complexity of assessing reliability and selecting methods increases
Solution Approach 1:
The patent changes the parameter used for method selection from a complex multi-criteria reliability assessment to a simple error magnitude comparison. Instead of evaluating multiple reliability factors, the system calculates the expected error for each method (integration method vs. open-circuit voltage method) and selects the method with the smaller error, significantly simplifying the decision process while maintaining accuracy.
3Measurement precision
If the open-circuit voltage method is used to determine state of charge, then accuracy is improved during idle phases, but the method cannot be applied during battery operation when current flows
Solution Approach 1:
The patent makes the calculation method dynamic by automatically switching between the integration method and the open-circuit voltage method based on real-time battery conditions. During idle phases when accuracy is critical, the system uses open-circuit voltage measurement; during operation when current flows, it uses integration. This dynamic adaptation allows the system to maintain high accuracy across all operational states.
Data Source
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AI summary
The invention relates to a method for determining the charge state (SOC) of a battery (1) on the basis of the open-circuit voltage (Uo) thereof, which may be determined using different methods. The accuracy of the charge state calculation may be optimized if the error (err_Uo) of the open-circuit voltage (Uo) is calculated, which would result from the use of a first and at least one further method for determining the open-circuit, and the charge state (SOC) is determined on the basis of that open-circuit voltage (Uo), the error (err_Uo) of which is smaller than the error (err_Uo) that would result from the use of a different method for the determination of the open-circuit voltage.