Battery Aging Estimation via Relaxation Voltage Decay
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Solution Overview
Problem
Existing methods for determining the state of aging of electrochemical batteries are inefficient, requiring long measurement times and being applicable only at full charge or discharge states, which limits real-time estimation and updating, especially in automotive applications where reduced relaxation phases occur frequently.
Innovation Solution
A method involving continuous measurement of voltage signals during battery relaxation, calculation of a logarithmic signal, and estimation of the aging state parameter using a modeling function and a predetermined map, allowing for the determination of battery aging regardless of the charge level, with reduced computational resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If open-circuit voltage measurement is used to determine battery aging state, then measurement accuracy is improved, but measurement time increases significantly as equilibrium requires over one hour
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the relationship between voltage decay characteristics and aging state parameters during battery relaxation. Instead of waiting for full equilibrium, the system performs measurements during the transient relaxation phase and uses pre-stored lookup tables to determine aging state, thereby avoiding the time-consuming wait for thermodynamic equilibrium while maintaining measurement accuracy
Solution Approach 2:
The patent uses short-lived voltage transient signals during relaxation that would otherwise be discarded as waste information. By extracting useful aging state data from these temporary, non-equilibrium voltage fluctuations, the system converts what would be considered wasted relaxation time into a productive measurement opportunity
2Reliability
If full charge requirement is imposed for aging determination, then measurement reliability is improved, but applicability to partial charges deteriorates
Solution Approach 1:
The patent changes the measurement parameter from requiring full charge states to utilizing voltage decay characteristics during relaxation phases. By monitoring the rate and pattern of voltage decay after charge interruption at any state, the system can determine aging state parameters without requiring the battery to be fully charged, thereby extending applicability to partial charge conditions while maintaining reliability through characteristic analysis
3Productivity
If continuous monitoring during relaxation is implemented, then real-time estimation capability is improved, but computational complexity increases
Solution Approach 1:
The patent uses copying by creating simplified representations of the complex relaxation voltage curve through characteristic parameter extraction. Instead of processing the entire continuous voltage signal, the system identifies key features (initial voltage, decay rate, inflection points) and uses these copied characteristics to query pre-stored lookup tables, thereby achieving real-time estimation with minimal computational complexity
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
Enables accurate and efficient determination of battery aging in real-time, independent of the battery's state of charge, facilitating improved battery management and integration in on-board applications.
Implementation Method 1
the rate of change of the battery voltage signal during relaxation, when expressed as a logarithmic signal, is proportional to the rate of change of the phase transformation rate (or autocatalysis rate) of the reactants during relaxation
Implementation Method 2
the volumetric concentrations of the reactants evolve in an S-shaped or sigmoid curve with respect to time
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a method for estimating the state of ageing of an electrochemical battery based on estimating a parameter representative of the autocatalysis speed during relaxation. According to the invention, the method comprises the steps of continuously calculating (203), during the relaxation of the battery, a logarithmic signal of the voltage in relaxation, calculating (207) a function for modelling the logarithmic signal, calculating (208) a second parameter representative of the rate of change of the function for modelling the logarithmic signal during relaxation, and estimating (209) the state of ageing parameter as a function of the second parameter and of a predetermined mapping.