Secondary Battery Aging Estimation via Segmented Calendar Cycle Models
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Solution Overview
Problem
Conventional degree-of-aging integration models for secondary batteries fail to accurately estimate the aging of batteries by not distinguishing between calendar and cycle states, leading to underestimation of aging due to sudden changes in reference equivalent time and slope of aging profiles.
Innovation Solution
An apparatus and method that measure current and temperature to determine the state of charge and operation state of a secondary battery, using cumulative degree-of-aging models to separately calculate calendar and cycle aging, and calculating a weighted average of these aging components based on their respective times to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional degree-of-aging integration model is used without distinguishing between calendar and cycle states, then the calculation process is simple, but the estimation accuracy of battery aging is poor
Solution Approach 1:
The patent divides the aging process into two distinct segments: calendar aging (occurring during no-load states) and cycle aging (occurring during charge-discharge states). Each segment has its own aging profile and reference equivalent time calculation method. This segmentation allows for more accurate estimation by accounting for the different mechanisms and rates of aging under different operational conditions, directly resolving the contradiction between estimation accuracy and model complexity.
2Measurement precision
If reference equivalent time is suddenly changed in conventional models, then the calculation remains continuous, but the slope of aging profile changes abruptly causing underestimation of aging
Solution Approach 1:
The patent implements dynamic adjustment of reference equivalent time based on the current operational state. When transitioning between calendar and cycle states, the reference equivalent time is adjusted gradually rather than suddenly, and the slope of the aging profile is dynamically modified to ensure continuity. This dynamic approach prevents abrupt changes in the aging profile while maintaining calculation continuity, resolving the contradiction between accuracy and stability.
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 a more accurate estimation of secondary battery aging by independently calculating changes in calendar and cycle aging, reflecting actual usage patterns and reducing estimation errors, especially when the slope of the aging profile is small.
Implementation Method 1
a current measuring unit configured to measure a current of the secondary battery and output a current measurement
Implementation Method 2
a temperature measuring unit configured to measure a temperature of the secondary battery and output a temperature measurement
Implementation Method 3
Secondary batteries generate electric energy by electrochemical oxidation and reduction reactions
Implementation Method 4
when a secondary battery is in a cycle state, Joule heat is generated while a charge or discharge current flows
Data Source
AI summary
An apparatus for estimating a degree of aging of a secondary battery is configured to: determine a current and a temperature of the secondary battery; determine a state of charge from the current of the secondary battery; determine a degree of calendar aging by applying a cumulative degree-of-aging model to a degree-of-calendar-aging profile corresponding to the determined state of charge and the determined temperature while the secondary battery is in a calendar state; determine a degree of cycle aging by applying the cumulative degree-of-aging model to a degree-of-cycle-aging profile corresponding to the state of charge, the temperature, and the current of the secondary battery while the secondary battery is in a cycle state; and determine, as the degree of aging of the secondary battery, a weighted average value calculated for the determined degree of calendar aging and the determined degree of cycle aging based on calendar time and cycle time.