Secondary Battery Capacity Estimation from Partial Charging Curves

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Solution Overview

Problem

Existing methods for secondary battery degradation determination, such as those described in Japanese Unexamined Patent Application Publication No. 2022-020404, require significant time and resources as they need to fully charge and discharge batteries to acquire charging and discharging characteristics, making them inefficient for recycling processes.

Innovation Solution

A secondary battery degradation determination apparatus and method that calculates an estimated electric capacity using a multiple regression model or trained neural network, based on charging and discharging curves, allowing for quick and efficient degradation assessment without the need for full charging and discharging cycles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If full charging and discharging cycles are performed to acquire charging and discharging characteristics, then degradation determination accuracy is improved, but assessment time increases significantly

Engineering Contradiction:
Improvedegradation determination accuracyVSAvoidassessment time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies partial action by performing only a charging process or a shortened charging-discharging cycle instead of complete full charging and discharging cycles. The controller calculates estimated electric capacity based on partial charging data (e.g., charging curve slope, voltage changes during charging) combined with battery usage history, achieving sufficient degradation assessment accuracy without requiring full discharge cycles, thus significantly reducing assessment time.

Inventive Principle:
Principle #16Partial or excessive action

2Reliability

If charging and discharging characteristics are acquired through full cycles, then degradation determination reliability is improved, but resource consumption increases

Engineering Contradiction:
Improvedegradation determination reliabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system uses partial charging data combined with historical usage information to estimate degradation, avoiding the need for complete charging and discharging cycles. This reduces energy consumption while maintaining reliability through the use of regression models that incorporate multiple factors including charging curves, discharge curves, and battery usage history.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent performs preliminary charging to acquire charging characteristics, and optionally performs preliminary discharge to acquire discharging characteristics before calculating degradation. By obtaining necessary data through preliminary partial cycles rather than full cycles, the system reduces energy consumption while ensuring sufficient data quality for reliable degradation determination.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If complete charging and discharging cycles are performed, then charging and discharging characteristics are accurately acquired, but processing complexity increases

Engineering Contradiction:
Improvecharacteristics acquisition accuracyVSAvoidprocess complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent simplifies the process by requiring only charging characteristics (and optionally discharge characteristics) rather than both complete charging and discharging cycles. The controller calculates estimated electric capacity using regression models based on charging curve data combined with battery usage history, reducing process complexity while maintaining measurement precision through the use of historical data integration.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4290255A1Secondary battery degradation determination apparatus and secondary battery degradation determination method
Publication Date: 2023.12.13 TOYOTA SYST CORP
  • EP4290255A1 patent drawingFigure 1
  • EP4290255A1 patent drawingFigure 2
  • EP4290255A1 patent drawingFigure 3

AI summary

A secondary battery degradation determination apparatus configured to perform degradation determination for a secondary battery (20) as a determination target includes a processor. The processor is configured to calculate an estimated electric capacity of the secondary battery (20), based on at least a slope between any two points on a charging curve indicating a charging characteristic of the secondary battery (20); and perform the degradation determination for the secondary battery (20), based on the estimated electric capacity that is calculated.