Battery Charge Estimation Using Impedance Correction
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Solution Overview
Problem
Existing battery state estimating apparatuses face challenges in accurately estimating the charge amount of batteries with multiple electrode bodies due to variations in temperature and deterioration states, leading to discrepancies between estimated and actual charge amounts, which can result in overcharge or over-discharge.
Innovation Solution
A battery state estimating apparatus that includes a voltage detector, an impedance detector, a first estimator, a second estimator, and a determinator to estimate the charge amount based on voltage and impedance, with a predetermined range to determine when to use impedance-corrected values for accurate estimation, thereby preventing overcharge or over-discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If voltage-based charge amount estimation is used for batteries with multiple electrode bodies, then the estimation process is simple, but the estimation accuracy deteriorates due to variations in temperature and deterioration state across electrode bodies
Solution Approach 1:
The patent combines voltage-based estimation and impedance-based estimation into a unified charge amount determination system. The charge amount determination unit integrates results from both estimation methods, using impedance information to correct voltage-based estimates when discrepancies are detected, thereby resolving the contradiction between simplicity and accuracy.
Solution Approach 2:
The system implements feedback by using impedance measurement results to validate and correct voltage-based charge amount estimates. When the charge amount determined from impedance differs from the voltage-based estimate beyond a threshold, the system adjusts the voltage-based estimate using the impedance information, creating a self-correcting mechanism that improves accuracy.
2Measurement precision
If separately detecting voltages of each electrode body is used to reduce variations, then the estimation accuracy improves, but the apparatus configuration becomes complicated
Solution Approach 1:
The patent introduces impedance as an intermediary parameter that reflects the collective state of all electrode bodies without requiring individual measurements. Impedance measurement serves as a mediator that captures variations in temperature and deterioration across electrode bodies through a single measurement, avoiding the need for multiple voltage detectors while maintaining accuracy.
3Measurement precision
If impedance-based charge amount estimation is used, then the estimation accuracy improves by accounting for temperature and deterioration variations, but the measurement and calculation complexity increases
Solution Approach 1:
The system applies partial action by using impedance information selectively rather than continuously. The charge amount determination unit only activates impedance-based correction when the difference between voltage-based and impedance-based estimates exceeds a predetermined threshold, reducing unnecessary calculations while maintaining accuracy when needed.
4Ease of operation
If voltage-based estimation is used, then the measurement process is simple, but the reliability deteriorates due to unintended discrepancy between estimated and actual charge amount
Solution Approach 1:
The system implements feedback by using impedance measurement results to validate and correct voltage-based charge amount estimates. When the charge amount determined from impedance differs from the voltage-based estimate beyond a threshold, the system adjusts the voltage-based estimate using the impedance information, creating a self-correcting mechanism that improves reliability.
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
The apparatus accurately estimates the charge amount of batteries with multiple electrode bodies by using both voltage and impedance measurements, ensuring precise control and preventing battery overcharge or over-discharge, even in conditions of temperature and deterioration variations.
Implementation Method 1
a voltage detector configured to detect a voltage between a positive electrode and a negative electrode of a battery
Implementation Method 2
an impedance detector configured to detect an impedance of the battery
Data Source
AI summary
A battery state estimating apparatus is provided with; a voltage detector configured to detect a voltage between a positive electrode and a negative electrode of a battery; an impedance detector configured to detect an impedance of the battery; a first estimator configured to estimate a first temporary value of a charge amount of the battery; a second estimator configured to estimate a second temporary value of the charge amount of the battery; and a determinator configured (i) to determine that the first temporary value is the charge amount of the battery if the first temporary value or the second temporary value is out of a predetermined range, and (ii) to determine that the second temporary value, or a corrected value of the first temporary value is the charge amount of the battery if the first temporary value or the second temporary value is within the predetermined range.