Battery Parameter Estimation Using Dynamic Charging Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for estimating the open-circuit voltage and state of charge (SOC) of secondary batteries, particularly during dynamic use, are either complex or inaccurate, especially when using blended cathode materials, which complicates accurate SOC estimation in electric vehicles and hybrid vehicles.
Innovation Solution
An apparatus and method that measures current-voltage data during specific charging patterns, calculates a linear approximation equation to estimate the open-circuit voltage, and uses this to estimate the SOC, incorporating a lookup table or function to account for temperature and voltage correlations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex mathematical models or experimentally-made lookup tables are used to estimate open-circuit voltage, then estimation capability is provided, but calculation complexity increases and accuracy reduces under dynamic conditions
Solution Approach 1:
The patent changes the parameter of charging current from constant to dynamically varying (increasing to peak then decreasing), which allows the battery to reach a relaxed state where polarization is minimized. This parameter change enables accurate open-circuit voltage estimation during dynamic conditions without requiring complex mathematical models or lookup tables.
2Ease of operation
If constant current charging is used, then charging process is simple, but polarization accumulates and prevents accurate open-circuit voltage estimation
Solution Approach 1:
The patent applies periodic action by varying the charging current in a structured manner (increasing to a peak value then decreasing) rather than maintaining constant current. This periodic variation allows the battery to transition through different states, ultimately reaching a relaxed state that enables accurate voltage estimation while maintaining operational simplicity.
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 allows for reliable and accurate estimation of open-circuit voltage and SOC during dynamic charging, improving the reliability of parameter estimation for secondary batteries with blended cathode materials by reducing polarization accumulation.
Implementation Method 1
A battery is a device that produces electrical energy through electrochemical oxidation and reduction reactions
Implementation Method 2
lithium ions de-intercalated from an anode material included in an anode moves to a cathode through an electrolyte and are intercalated into a cathode material included in the cathode
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Disclosed is an apparatus and method for estimating a parameter of a secondary battery. The apparatus according to the present disclosure includes a sensor means configured to measure a plurality of current-voltage data while a charging current decreases when a secondary battery is charged in such a pattern that the charging current increases to a peak value and then decreases, and a control means configured to receive an input of the plurality of current-voltage data from the sensor means, calculate a linear approximation equation representing a correlation between a current and a voltage from the plurality of current-voltage data, and estimate a Y intercept of the linear approximation equation as an open-circuit voltage of the secondary battery.