Battery Residual Capacity Calculation Using Aging Model

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Solution Overview

Problem

Existing methods for calculating the residual electric quantity of a battery, such as the Coulombmeter and impedance track methods, do not account for the continuous decrease in maximum discharge capacity due to dead lithium and electrolyte consumption, leading to inaccurate calculations and reduced user experience.

Innovation Solution

A method and apparatus that utilize a battery aging model, obtained by tracking the number of charging and discharging cycles, fitting curves based on open circuit voltage and electric quantity variations, and adjusting for attenuation ratios to accurately determine the residual electric quantity, incorporating a coulombmeter when available or using correction coefficients when not.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the Coulombmeter method or impedance track method is used to calculate residual electric quantity, then the calculation process is simple, but the calculation accuracy deteriorates due to battery aging effects

Engineering Contradiction:
Improveresidual electric quantity calculation accuracyVSAvoidcalculation model complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent pre-establishes a battery aging model through curve fitting before actual use. The model is built by collecting battery data at different charging cycles, fitting open circuit voltage curves, and determining aging parameters in advance. This preliminary preparation allows the system to quickly apply the model during operation without real-time complexity, resolving the contradiction between accuracy and computational complexity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces a battery aging model as an intermediary between the simple Coulombmeter/impedance methods and the actual battery system. This model acts as a mediator that compensates for battery aging effects by using pre-fitted curves and aging parameters, enabling accurate residual electric quantity calculation without requiring complex real-time computations.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If traditional methods are used without considering battery aging, then the device complexity remains low, but the reliability of residual electric quantity measurement deteriorates over time

Engineering Contradiction:
Improveresidual electric quantity measurement reliabilityVSAvoidbattery aging model complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The battery aging model is constructed in advance by collecting battery data at different charging cycles, fitting open circuit voltage curves, and determining aging parameters before actual use. This preliminary preparation ensures the model is ready to compensate for aging effects from the start, maintaining measurement reliability without adding operational complexity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent incorporates battery aging feedback into the residual electric quantity calculation by using the established aging model to adjust measurements. The model provides feedback on how battery capacity degrades over charging cycles, allowing the system to compensate for aging effects and maintain reliable measurements throughout the battery's lifecycle.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3955014B1Method and apparatus for obtaining residual electric quantity, and electronic device
Publication Date: 2024.02.21 BEIJING XIAOMI MOBILE SOFTWARE CO LTD
  • EP3955014B1 patent drawingFigure 1~3
  • EP3955014B1 patent drawingFigure 4
  • EP3955014B1 patent drawingFigure 5~6

AI summary

A method for obtaining a residual electric quantity of a battery in an electronic device includes: obtaining a present electric quantity variation of a battery within a present detection period; obtaining a maximum discharge electric quantity of the battery corresponding to a number of times of charging and discharging within the present detection period; and obtaining a present residual electric quantity of the battery based on the maximum discharge electric quantity and the present electric quantity variation.