Battery SOC Estimation Using Integrated Voltage Error Feedback
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Solution Overview
Problem
Existing methods for estimating the state of charge (SOC) of batteries, such as the ampere-counting model and equivalent circuit model, suffer from inaccuracies due to measurement errors and nonlinear battery characteristics, leading to accumulated errors in estimated voltage and SOC.
Innovation Solution
A device that measures battery voltage and current, using a processor to estimate a second voltage by integrating voltage errors and correcting it based on an integrated voltage error within a reference error range, thereby improving SOC estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the ampere-counting model is used to estimate SOC, then the estimation can be performed continuously, but measurement error accumulates over time leading to deteriorating accuracy
Solution Approach 1:
The patent implements a feedback mechanism by comparing the estimated voltage with the actual voltage measured by the voltage sensor, calculating voltage error, and using this error to correct the ampere-counted SOC. The voltage error is integrated over time and used to adjust the SOC estimation, creating a closed-loop system that continuously corrects accumulation errors.
2Measurement precision
If the equivalent circuit model is used to estimate SOC, then the estimation can account for battery nonlinearities, but the model becomes complex and difficult to design to perfectly simulate battery characteristics
Solution Approach 1:
The patent segments the SOC estimation into two independent parts: (1) an ampere-counting model that provides continuous SOC estimation, and (2) a voltage-based correction mechanism that accounts for voltage deviations. This segmentation allows each part to have simpler characteristics while together they achieve accurate SOC estimation without requiring a complex equivalent circuit model.
3Measurement precision
If voltage estimation is performed using extended Kalman filter, then SOC can be estimated more accurately, but error in estimated voltage accumulates and deteriorates SOC estimation accuracy
Solution Approach 1:
The patent uses the voltage sensor to continuously monitor the actual battery voltage and compares it with the estimated voltage from the extended Kalman filter. The voltage error is integrated over time and fed back to correct the SOC estimation, creating a feedback loop that prevents error accumulation and improves both voltage and SOC estimation reliability.
Data Source
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AI summary
A device for estimating state of charge of battery of the present disclosure includes: a sensing unit configured to measure at least one of a first voltage and an OCV of a battery; and a processor operably coupled to the sensing unit. The processor is configured to estimate a second voltage of the battery based on the OCV of the battery or a previously estimated first SOC, calculate a counted voltage error by counting a voltage error between the first voltage and the second voltage of the battery, correct the second voltage of the battery depending on whether the counted voltage error is included in a reference error range, and estimate a first SOC of the battery based on the second voltage or the corrected second voltage.