Battery Internal Resistance Calculation via Regression Analysis
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Solution Overview
Problem
Existing battery systems face challenges in accurately calculating internal resistance, leading to potential inaccuracies in detecting temperature rises and calculating open circuit voltage, especially under high current conditions where non-linearity in I-V plots occurs.
Innovation Solution
A battery system that includes a voltage sensor, current sensor, and controller to perform regression analysis on current-voltage data, calculating internal resistance from the slope of a regression line and determining the appropriateness of operations based on resistance differences between multiple detection groups or voltage differences across current ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If regression analysis is performed on current-voltage data to calculate internal resistance, then internal resistance can be obtained, but calculation accuracy deteriorates under high current conditions due to non-linearity in I-V plots
Solution Approach 1:
The patent divides the current-voltage data into multiple groups based on current magnitude ranges. Regression analysis is performed separately for each group, and the results are combined to obtain the final internal resistance value. This segmentation allows the system to handle non-linear regions by treating them as separate linear segments, thereby maintaining calculation accuracy across different operating conditions including high current scenarios.
2Productivity
If internal resistance calculation is performed using existing methods, then operation can be executed, but detection accuracy of temperature rise and open circuit voltage calculation deteriorate
Solution Approach 1:
The patent incorporates a validation mechanism that checks the reliability of internal resistance calculation results before executing operations. By evaluating whether the calculated internal resistance meets predetermined reliability criteria, the system provides feedback to determine if the calculation should be used for temperature rise detection and OCV calculation. This feedback loop ensures that only accurate calculations are used, thereby maintaining high detection accuracy while enabling operation execution.
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
This approach enhances the accuracy of internal resistance calculation, allowing for more precise operations and improved detection of battery abnormalities, thereby ensuring reliable battery performance.
Implementation Method 1
a voltage sensor configured to detect a voltage of the battery
Implementation Method 2
a current sensor configured to detect a current that passes through the battery
Implementation Method 3
highly accurate calculation of the internal resistance of the battery makes it possible to detect a temperature rise in the battery (such as abnormal heat generation in the battery) due to the Joule heat generated in the battery
Data Source
AI summary
A battery system includes a controller that performs a calculation to calculate an internal resistance of a battery, and executes a predetermined operation based on the result. The calculation includes obtaining a regression line through a regression analysis of a current-voltage plot obtained from voltage sensor and current sensor, and calculating the internal resistance from a slope of the regression line. The controller calculates a first internal resistance through the calculation based on a first group of detection values of the voltage and current detected a plurality of times, and calculate a second internal resistance through the calculation based on a second group of detection values. The controller executes the predetermined operation when a resistance difference between the first and second internal resistances is smaller than a reference value, and does not execute the operation when the resistance difference is larger than the reference value.