Battery Charge State Correction via Full Charge Feedback

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Solution Overview

Problem

Existing battery charge state calculation methods using terminal voltage maps are prone to errors due to battery deterioration, leading to inaccurate displays that can discomfort users.

Innovation Solution

A device and method that calculates a correction value when the battery is fully charged, updating it only at full charge detection and maintaining it until the next full charge, to correct and stabilize the displayed charge state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a map showing the relationship between battery terminal voltage and battery capacity is used to calculate the state of charge, then the calculation method is simple, but the error in the calculated value becomes large due to battery deterioration

Engineering Contradiction:
Improvecalculation method complexityVSAvoidcharge state calculation accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism by detecting the actual terminal voltage at full charge and comparing it with the predicted voltage from the map. The difference (correction value) is stored and used to adjust subsequent calculations. This closed-loop feedback corrects the accumulation of errors caused by battery deterioration while maintaining the simplicity of the map-based approach.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the parameter used for calculation by introducing a correction value that adjusts the terminal voltage or capacity based on the difference between actual and predicted full charge values. This parameter adjustment compensates for battery deterioration effects without requiring a complete recalculation method.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the correction value is updated frequently to maintain accuracy, then the charge state accuracy improves, but the display shows large fluctuations that discomfort the user

Engineering Contradiction:
Improvecharge state accuracyVSAvoiddisplay stability
Core Design Contradiction:
Measurement precisionVSStability of the object's composition

Solution Approach 1:

The patent performs preliminary correction by calculating the correction value at full charge before normal operation begins. This advance correction establishes a baseline that prevents large fluctuations during subsequent charging cycles, as the correction is already applied before the user starts using the battery.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements periodic updates of the correction value only at full charge events rather than continuously. This periodic action maintains accuracy by correcting at meaningful intervals while avoiding excessive updates that would cause display fluctuations and user discomfort.

Inventive Principle:
Principle #19Periodic action

3Stability of the object's composition

If the correction value is updated only at full charge detection, then the display stability improves, but the correction may not account for gradual battery deterioration between full charge events

Engineering Contradiction:
Improvedisplay stabilityVSAvoidcorrection accuracy
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent enables the system to self-correct by automatically detecting full charge conditions and updating the correction value without user intervention. The system monitors its own state and performs necessary corrections autonomously, ensuring both stability and reliability are maintained through self-managed updates.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2899834B1Charge state calculation device and charge state calculation method
Publication Date: 2021.02.24 NISSAN MOTOR CO LTD
  • EP2899834B1 patent drawingFigure 1
  • EP2899834B1 patent drawingFigure 2A~2B
  • EP2899834B1 patent drawingFigure 3

AI summary

This charge state calculation device is provided with a detection means for detecting the voltage and/or the current of a battery (20), a charge state calculation means for calculating the charge state of the battery (20) from the values detected by the detection means, a full charge detection means for detecting the full charge of the battery, a correction value calculation means for calculating, when the full charge of the battery (20) is detected, a correction value for correcting the charge state calculated by the charge state calculation means to the charge state of 100%, a correction means for correcting a charge state calculated by the charge state calculation means by the correction value, and a display means for displaying the charge state thus corrected by the correction means, wherein the correction value calculation means updates the correction value only when the full charge of the battery (20) is detected, and maintains the updated correction value until next time the full charge of the battery will be detected.