Valve Regulated Lead-Acid Battery SOC Estimation with Liquid Reduction
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Solution Overview
Problem
Conventional methods for estimating the state of charge (SOC) of valve-regulated lead-acid batteries are inaccurate due to the small amount of electrolyte solution, which affects sulfuric acid concentration, leading to decreased estimation accuracy over time.
Innovation Solution
A method that identifies the overcharge amount and uses a correlation between overcharge and liquid reduction to estimate the SOC, incorporating temperature adjustments for more accurate liquid reduction conversion rates, thereby improving SOC estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the state of charge is estimated simply based on the measurement result of the open circuit voltage as in the conventional method, then the estimation process is simple, but the estimation accuracy of the state of charge will be gradually deteriorated in the process of using the battery
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing multiple OCV-SOC correlation data sets corresponding to different liquid reduction amounts before actual battery operation. During state of charge estimation, the system first determines the current liquid reduction amount based on usage history, then selects the appropriate pre-prepared correlation data set that matches the current condition. This approach allows the system to use accurate, condition-specific correlation data without performing complex real-time calculations, thereby maintaining both high estimation accuracy and computational efficiency.
2Ease of operation
If the valve regulated lead-acid battery has a small amount of electrolyte solution, then the battery has high degree of freedom in installation posture and easy maintenance, but even a small liquid reduction amount has a large effect on the sulfuric acid concentration, leading to decreased estimation accuracy over time
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the OCV-SOC correlation parameters based on the liquid reduction amount. Instead of using a fixed correlation, the system modifies the correlation characteristics according to the current electrolyte condition. The liquid reduction amount serves as a key parameter that determines which correlation data set to use, allowing the estimation model to adapt to changing battery conditions while maintaining accuracy despite the small electrolyte volume in valve-regulated batteries.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise estimation of SOC by accounting for liquid reduction and temperature effects, enhancing the accuracy of SOC estimation in valve-regulated lead-acid batteries.
Implementation Method 1
an open circuit voltage acquisition step of acquiring an open circuit voltage of the lead-acid battery after the reference time
Implementation Method 2
estimation of the liquid reduction amount of the electrolyte solution and the sulfuric acid concentration
Implementation Method 3
the valve regulated lead-acid battery absorbs gas generated from the inside during use by an electrode plate, and thus the electrolyte solution is less likely to be reduced
Data Source
AI summary
A method for estimating a state of charge of a valve regulated lead-acid battery includes; an overcharge amount identification step of identifying an overcharge amount when the lead-acid battery is overcharged after an arbitrary reference time; an open circuit voltage acquisition step of acquiring an open circuit voltage of the lead-acid battery after the reference time; and a state-of-charge estimation step of estimating a state of charge of the lead-acid battery based on the acquired open circuit voltage and a correlation between an open circuit voltage and state of charge in which a rate of change of the state of charge with respect to the open circuit voltage is smaller as the overcharge amount from the reference time until an acquisition time of the open circuit voltage is larger.