Battery State of Charge Estimation via Voltage Drift Detection
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Solution Overview
Problem
Existing battery management systems face challenges in accurately estimating the state of charge and state of health of batteries due to degradation over time and aging, requiring frequent complete charge or discharge cycles, which are time-consuming and inefficient.
Innovation Solution
A method that involves detecting specific points on the time derivative of the voltage curve during charging or discharging to estimate the state of charge and health, allowing for precise resetting of estimation algorithms without the need for full charge or discharge cycles, using temperature control and dispersion balancing to optimize the estimation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complete charge or discharge cycles are performed to reset the state of charge gauge, then the estimation accuracy is improved, but the time consumption increases significantly
Solution Approach 1:
The patent extracts the essential information needed for resetting the state of charge gauge from the complete charge/discharge process. By detecting specific characteristic points (such as voltage plateaus or inflection points) during partial charging or discharging, the system obtains sufficient data to reset the gauge without requiring full charge/discharge cycles, thus reducing time while maintaining accuracy
Solution Approach 2:
Instead of performing complete charge or discharge cycles (excessive action), the patent uses partial charging or discharging processes that are sufficient to detect characteristic points and reset the gauge. This partial action approach achieves the resetting objective without the time penalty of full cycles
2Loss of time
If voltage measurement during rest phase is used to reset the state of charge gauge, then the time loss is reduced, but the measurement precision requirement increases
Solution Approach 1:
The patent changes the measurement parameter from static open-circuit voltage (which requires very high precision) to dynamic voltage characteristics during charging/discharging processes. By measuring voltage changes during active processes and detecting characteristic points on the voltage curve, the system reduces the precision burden on sensors while maintaining resetting accuracy
3Measurement precision
If complete discharge and recharging is performed to reset the state of health estimation, then the estimation accuracy is improved, but the productivity decreases
Solution Approach 1:
The patent extracts the necessary information for state of health resetting from partial charge/discharge processes by detecting characteristic points. This extraction approach provides sufficient data to update the state of health estimation without requiring complete charge/discharge cycles, thus maintaining accuracy while improving productivity
Solution Approach 2:
The system performs preliminary detection of characteristic points during normal charging or discharging operations to accumulate data for state of health estimation. This preliminary action allows the system to reset state of health without waiting for complete charge/discharge cycles, improving operational efficiency
Data Source
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AI summary
The invention relates to a method for evaluating the charge status of a battery, comprising at least one phase for estimating the charge status of the battery using an algorithm for estimating the charge status and at least one phase for recalibrating the estimating algorithm employed during the estimating phase, characterized in that the recalibration phase comprises carrying out the following steps: - detecting an actual value of a charge status of the battery at a given moment by carrying out the following steps: charging or discharging (E8) the battery, between first and second charge status levels; - measuring (E12) the voltage across the terminals of the battery during that charge or discharge; - evaluating the time drift (E14) of said voltage; - detecting at least one particular point (E16) of that drift corresponding to an actual, known and predefined charge status value, - recalibrating (E20) the estimating algorithm, knowing said actual charge status value at said given moment.