Battery State Estimation Parameter Thresholding
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Solution Overview
Problem
Existing battery state estimation methods suffer from significant identification errors in certain parameters, which can lead to improper estimation of the battery state, especially when these errors are large.
Innovation Solution
A battery state estimating device and method that detects current and terminal voltage, uses a predetermined battery model to estimate terminal voltage, and performs upper limit processing by setting certain parameters to a threshold when they exceed a predetermined value, thereby reducing estimation errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential identification of battery model parameters is performed to improve estimation accuracy, then the difference between measured and estimated voltage values converges to zero, but identification errors in certain parameters can become large and cause improper estimation of battery state
Solution Approach 1:
The patent applies parameter changes by introducing upper limit thresholds for battery model parameters. When identified parameters exceed these thresholds, they are constrained to the threshold values, preventing identification errors from becoming excessively large and causing improper battery state estimation while maintaining voltage estimation accuracy.
Solution Approach 2:
The patent implements feedback by continuously monitoring identified parameter values against predetermined upper limits. When parameters exceed thresholds, the system applies corrective action by setting them to the threshold values, creating a feedback loop that maintains reliable battery state estimation while preserving voltage estimation precision.
2Reliability
If upper limit processing is applied to constrain parameter values, then identification errors are reduced and battery state estimation reliability improves, but the natural convergence behavior of parameter identification may be altered
Solution Approach 1:
The patent applies beforehand cushioning by establishing upper limit thresholds for battery model parameters before identification errors can cause harmful effects. These predetermined thresholds act as protective constraints that prevent parameter values from diverging excessively, cushioning against potential estimation failures while maintaining overall system reliability.
Data Source
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AI summary
A battery state estimating device being one aspect of the present invention detects a current and a terminal voltage of a secondary battery, estimates a terminal voltage of the secondary battery which is based on a predetermined battery model by using measured values I(k) and V(k) respectively of the detected current and the detected terminal voltage, and sequentially identifies a parameter φ^(k) of the battery model in such a way that the difference between a value based on the measured value of the terminal voltage and an estimate value of the terminal voltage converges to zero. Then, when a certain parameter φn in the identified parameter is equal to or larger than a predetermined first threshold δ1, the battery state estimating device performs upper limit processing of setting the value of the certain parameter φn to the first threshold δ1.