Battery Power Limit Prediction Using an Equivalent Circuit Model
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Solution Overview
Problem
Existing battery management systems struggle to accurately predict terminal voltage and net resistance, leading to incorrect determination of power limits during charging and discharging, which compromises battery safety.
Innovation Solution
A method and battery management system that utilizes an equivalent circuit model to predict terminal voltage and net resistance using equations based on measured current and resistance, allowing for periodic updates of charge and discharge power limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If terminal voltage and current are measured directly without prediction, then measurement simplicity is maintained, but prediction accuracy of terminal voltage deteriorates under fluctuating conditions
Solution Approach 1:
The patent applies preliminary action by predicting terminal voltage and net resistance before actual charging/discharging operations. The equivalent circuit model pre-calculates these parameters based on current state, allowing the system to determine power limits in advance rather than reacting to real-time fluctuations, thus improving prediction accuracy while maintaining manageable system complexity
Solution Approach 2:
The patent introduces an equivalent circuit model as an intermediary between direct measurement and power limit determination. This model acts as a mediator that processes current measurements and predicts future terminal voltage and resistance, resolving the contradiction by providing accurate predictions without requiring direct complex real-time monitoring of fluctuating parameters
2Reliability
If power limit is determined based on incorrectly predicted terminal voltage, then determination speed is maintained, but battery safety deteriorates
Solution Approach 1:
The system performs preliminary prediction of terminal voltage and net resistance using the equivalent circuit model before determining power limits. This advance calculation ensures that power limits are based on accurate predicted values rather than incorrect real-time measurements, improving battery safety without significant time loss since the predictions are computed efficiently
Solution Approach 2:
The patent implements feedback by continuously updating the equivalent circuit model parameters based on actual measurements and using these updated parameters for subsequent predictions. This closed-loop approach ensures that prediction accuracy improves over time, enhancing battery safety while maintaining efficient determination timing through iterative refinement
3Measurement precision
If equivalent circuit model is used to predict terminal voltage and net resistance, then prediction accuracy improves, but calculation complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the battery into an equivalent circuit model with distinct components (resistors and capacitors). This segmentation allows separate estimation of individual parameters (R1, R2, C) and their contributions to terminal voltage and net resistance, improving prediction accuracy while managing calculation complexity through modular parameter estimation
Solution Approach 2:
The patent utilizes parameter changes by dynamically updating the equivalent circuit model parameters (resistances and capacitances) based on current battery state. This allows the model to adapt to changing battery conditions, maintaining high prediction accuracy while controlling calculation complexity through efficient parameter update strategies rather than full recalculation
Data Source
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AI summary
Disclosed is a method and a battery management system for periodically determining at least one of charge power limit and discharge power limit of a battery. The method according to an embodiment of the present disclosure includes predicting the terminal voltage and the net resistance of the battery after a predefined time from the current time using an equivalent circuit model for the battery, and determining the charge power limit or the discharge power limit of the battery from the predicted terminal voltage and net resistance.