Battery Management System Frequency-Based Ageing Discrimination
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Solution Overview
Problem
Existing battery management systems struggle to accurately model and differentiate between various types of ageing in electrochemical batteries, leading to suboptimal charging management and premature battery degradation.
Innovation Solution
A process for managing electrochemical batteries involves measuring internal resistance at different frequencies, comparing these measurements to reference values, and adjusting charging currents based on the type of ageing detected, thereby extending battery service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fast charging at high current levels is applied to electrochemical batteries, then charging speed and productivity are improved, but battery ageing is accelerated and service life decreases
Solution Approach 1:
The charging current intensity is made dynamic rather than fixed. The BMS continuously monitors internal resistance at multiple frequencies and adjusts the charging current in real-time based on the detected ageing type and battery state, allowing fast charging when conditions permit while preventing damage when ageing is detected
Solution Approach 2:
The system changes the operational parameters of charging by monitoring internal resistance across different frequency ranges (first frequency range for cycling ageing detection, second frequency range for calendar ageing detection) and adjusting charging current intensity accordingly, transforming the charging process from static to adaptive
2Device complexity
If fixed weight model equations are used to assess battery SOH, then the assessment process is simplified, but the accuracy of ageing discrimination is insufficient
Solution Approach 1:
The SOH assessment is segmented into multiple frequency measurements rather than using a single fixed model. The system measures internal resistance at a first frequency range to detect cycling ageing and at a second frequency range to detect calendar ageing, allowing discrimination between different ageing types through comparative analysis of results from each frequency range
Solution Approach 2:
The assessment moves from a single-dimension fixed weight model to a multi-dimensional approach by introducing frequency as an additional dimension. By measuring and comparing internal resistance across different frequency ranges, the system gains the ability to distinguish between different ageing mechanisms that a single-point measurement cannot detect
Data Source
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AI summary
A process of managing an electrochemical battery (10) comprising measuring at least one first internal resistance (RHF(t)) of the battery at at least a first frequency (f1) and comparing the measured first internal resistance (RHF(t)) with a first reference internal resistance (RHF,REF); if the first measured internal resistance is less than or equal to the first reference internal resistance, making a decision regarding continued use of the battery; and otherwise measuring at least one second internal resistance (RLF(t)) of the battery at least one second frequency (f2) lower than the first frequency and comparing a difference D(t) between the measured second and first internal resistances with a reference difference (DREF) between a second and the first reference internal resistances (RLF,REF, RHF,REF); and if the difference D(t) is greater than or equal to the reference difference, making a decision regarding a disqualification of the battery (10); and otherwise reducing an intensity of a fast charge and/or regeneration current for a subsequent charging step.