Battery Coulomb Counting with Temperature and Aging Compensation
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Solution Overview
Problem
Coulomb counter-based state of charge estimation in batteries is prone to error accumulation and does not account for changes due to battery temperature and aging, leading to reduced accuracy.
Innovation Solution
An apparatus and method that includes a first coulomb counter, a compensator, and a state of charge estimator, which calculates and compensates for charge variations using predicted open circuit voltage and overpotential values to reflect battery temperature and aging, reducing error accumulation and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If coulomb counter continuously accumulates measured currents to predict residual charge, then state of charge estimation can be performed with simple method, but error accumulation occurs and significantly degrades estimation accuracy over time
Solution Approach 1:
The patent implements feedback by continuously monitoring the difference between the estimated state of charge and actual state of charge, then using this error signal to adjust and correct the coulomb counter accumulation process. This feedback mechanism prevents error accumulation by constantly recalibrating the estimation based on actual measurements.
Solution Approach 2:
The patent changes parameters by introducing temperature and aging compensation factors that dynamically adjust the state of charge estimation. These parameter changes allow the system to account for variations in battery characteristics under different operating conditions, thereby maintaining accuracy without sacrificing the simplicity of the coulomb counter method.
2Device complexity
If coulomb counter uses fixed design capacity for state of charge calculation, then calculation is simple, but it does not reflect battery characteristics changes due to temperature and aging
Solution Approach 1:
The patent applies dynamics by transitioning from a static fixed capacity model to a dynamic capacity model that adapts to changing battery conditions. The system dynamically adjusts the capacity parameter based on temperature and aging state, allowing the coulomb counter to remain simple while accurately reflecting battery characteristic changes through real-time parameter updates.
Solution Approach 2:
The patent changes the capacity parameter from a fixed design value to a dynamic value that varies with temperature and aging. This parameter change enables the system to maintain simple calculations while accurately representing the battery's actual capacity under different operating conditions, thus improving adaptability without significantly increasing complexity.
3Reliability
If battery operates in low temperature state or aged condition, then full charge capacity is significantly reduced, but conventional coulomb counter does not reflect this reduction leading to lower estimation accuracy
Solution Approach 1:
The patent changes the capacity parameter to account for temperature and aging effects. By introducing compensation factors that modify the nominal capacity based on actual battery conditions, the system maintains reliable state of charge estimation across different operating conditions without requiring completely different measurement systems.
Solution Approach 2:
The patent implements feedback mechanisms that monitor temperature and aging indicators, then use this information to adjust the capacity parameters in the state of charge calculation. This feedback loop ensures the estimation remains reliable under varying conditions by continuously adapting to the battery's actual state.
Data Source
AI summary
Embodiments of the present disclosure includes an apparatus for estimating the state of charge of a battery, comprising: a first coulomb counter (STCC) for sampling a first charge variation (ΔQ) on the battery in a time comprising a number of predetermined periods, by adding up a battery current Im in each of the predetermined periods; a compensator for calculating a second charge variation (ΔQ_comp) by compensating for the first charge variation (ΔQ); a second coulomb counter (CCE) for calculating a first predicted charge amount (Qe) by adding up the second charge variation (ΔQ_comp); and a state of charge estimator for estimating the state of charge of the battery on the basis of the first predicted charge amount (Qe). The technique increases the accuracy of a state of charge estimation by compensating for characteristics according to battery temperature and aging.