Half Cell Free Capacity Estimation via Inflection Point Detection
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Solution Overview
Problem
Existing methods for estimating the state of charge (SOC) of secondary batteries, particularly lithium secondary batteries, require a reference electrode to be physically inserted between the positive and negative electrodes, which is impractical for various devices such as electric vehicles and energy storage systems.
Innovation Solution
An apparatus that measures battery voltage using a sensing unit and a processor to detect inflection points in SOC-voltage data, revises the SOC region of a half cell without a reference electrode by using SOC ratios, allowing for accurate estimation of free capacity based on SOC differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference electrode is physically inserted between the positive electrode and the negative electrode to measure the voltage of each electrode, then the SOC-voltage data of each electrode can be accurately estimated, but it becomes impossible to apply the method to various devices such as electric vehicles and energy storage systems
Solution Approach 1:
The patent extracts the reference electrode from the physical insertion method and replaces it with a virtual reference electrode implemented through software algorithms. The processor detects inflection points in the full cell SOC-voltage curve and uses these to revise the half cell SOC regions, eliminating the need for physical reference electrode insertion while maintaining estimation accuracy
Solution Approach 2:
The patent introduces inflection point detection as an intermediary mechanism between the full cell voltage measurement and the half cell SOC estimation. By detecting inflection points in the dV/dSOC curve and using them to revise SOC regions, the system mediates the measurement process without requiring direct physical access to individual electrodes
2Measurement precision
If the SOC region of a half cell is revised using inflection points detected from SOC-voltage data, then the free capacity can be accurately estimated without a reference electrode, but the complexity of the estimation algorithm increases
Solution Approach 1:
The patent performs preliminary detection of inflection points in the full cell SOC-voltage curve before estimating the half cell free capacity. By pre-identifying the inflection points and using them to define revised SOC regions, the algorithm prepares the necessary reference data in advance, simplifying the subsequent free capacity calculation
Solution Approach 2:
The patent creates a virtual model of the reference electrode functionality by copying the essential measurement function through inflection point detection. The revised SOC regions derived from inflection points serve as a virtual reference that replicates the information previously obtained only through physical reference electrodes
Data Source
AI summary
The present disclosure relates to an apparatus for estimating a battery free capacity, and more particularly, an apparatus for estimating a free capacity of a half cell of a battery. According to the present disclosure, it is possible to accurately estimate a free capacity of a half cell without inserting a reference electrode by revising an entire SOC region of a half cell by using an inflection point detected based on SOC-voltage data of a full cell and a half cell of the battery, respectively, and then estimating SOC-voltage data based on a SOC difference between the entire SOC regions before and after the revision.