Battery Model Identification via 3D Degradation Estimation
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Solution Overview
Problem
Current battery state estimation methods, such as Thevenin circuit models, compromise on accuracy and uniqueness in representing battery degradation, particularly in modeling capacitance effects during charging and discharging, and fail to accurately predict the state of health and function of batteries under constant current conditions.
Innovation Solution
A three-dimensional first principle degradation model is used to estimate battery degradation information from terminal voltage and current data, allowing for the identification of a more accurate circuit model that represents battery behavior at various levels of degradation, enabling precise estimation of state of health, state of function, and state of charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Thevenin circuit model is used for battery state estimation, then the model is simple and easy to implement, but the accuracy and uniqueness in representing battery degradation is compromised
Solution Approach 1:
The battery is segmented into multiple parallel equivalent circuits, each representing different degradation mechanisms (capacitance effects, ohmic resistance, polarization). This segmentation allows the model to capture complex degradation behaviors that a single Thevenin model cannot represent, improving accuracy while maintaining computational tractability through modular structure
Solution Approach 2:
The patent uses a composite modeling approach combining multiple circuit models (Thevenin elements) in parallel to create a more comprehensive representation of battery degradation. Each parallel branch represents different physical degradation mechanisms, and their combined effect provides accurate state estimation without requiring a single overly complex model
2Device complexity
If traditional circuit models are used, then the model structure is simple, but the ability to accurately predict state of health and function under constant current conditions deteriorates
Solution Approach 1:
The patent implements dynamic parameter estimation where circuit model parameters (resistance, capacitance values) are continuously updated based on real-time battery measurements and degradation state. This dynamic adaptation allows the model to accurately predict SOH and SOF under varying operating conditions including constant current scenarios, without requiring a statically complex model structure
Solution Approach 2:
The system uses feedback from real-time battery measurements (voltage, current, temperature) to continuously update the degradation state and adjust circuit model parameters. This feedback mechanism improves prediction reliability by ensuring the model adapts to actual battery behavior, compensating for the simplicity of the underlying circuit structure
Data Source
AI summary
A method, an apparatus, and a system for determining a state of a battery are provided. The method includes acquiring battery information from a sensor associated with the battery. The battery information includes at least terminal voltage and a terminal current. The method further includes estimating degradation information based on a first principle degradation model and the battery information. The first principle degradation model is a three dimensional model that includes a plurality of layers having one or more attributes representative of physical parameters of the battery. The method further includes identifying a circuit model based on the degradation information and the battery information, determining the state of the battery using the identified circuit model, and implementing a control action or a notification based on the determined state of the battery.