Rechargeable Battery SoH Estimation During DC Fast Charging
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Solution Overview
Problem
Existing methods for estimating the State of Health (SoH) of rechargeable batteries lack universality, requiring customized charging stations and providing only statistical indications, and do not accurately measure internal resistance.
Innovation Solution
A method and system that utilize a DC power charging process to calculate SoH using the formula SoH=(DE)/(SoCEND−SoCSTART), where DE is the energy provided during charging, and SoCSTART and SoCEND are initial and final State of Charge values, obtained from an electronic control unit, with a DC logger measuring current or power and a diagnostic device computing SoH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If customized charging stations are used to estimate SoH based on internal resistance extrapolation, then measurement precision may be improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies universality by enabling existing fast-charging stations to perform SoH estimation functions without customization. The method uses standard charging operations that any fast-charging station can execute, eliminating the need for specialized equipment while maintaining measurement capability across different battery types and manufacturers.
Solution Approach 2:
The patent implements self-service by having the battery itself provide the measurement data during normal charging operations. The battery's voltage and current characteristics during fast charging contain the information needed for SoH estimation, eliminating the need for external specialized measurement devices or customized charging infrastructure.
2Measurement precision
If complete discharge and charge cycles are performed to measure capacity, then SoH estimation accuracy is improved, but loss of time increases
Solution Approach 1:
The patent applies partial action by performing SoH estimation during a partial charging process rather than requiring complete charge cycles. The method calculates SoH based on energy delivered and state of charge changes during fast charging, obtaining sufficient data without completing the full charge cycle, thus reducing time loss while maintaining estimation accuracy.
Solution Approach 2:
The patent implements preliminary action by performing SoH estimation during the charging process itself rather than after complete charge cycles. The measurement is conducted preliminarily during the fast charging operation, providing quick SoH assessment without waiting for battery depletion or full charging completion.
3Ease of operation
If statistical indications are provided instead of actual internal resistance measurement, then ease of operation is improved, but measurement precision deteriorates
Solution Approach 1:
The patent substitutes direct electrical measurement with a computational approach. Instead of using complex measurement systems to directly measure internal resistance, the method calculates SoH using energy delivery data and state of charge changes during fast charging, replacing physical measurement complexity with mathematical computation based on readily available charging parameters.
4Adaptability or versatility
If different SoH definitions are used by various diagnostic tools, then adaptability to different vehicle manufacturers is improved, but loss of information increases
Solution Approach 1:
The patent changes the fundamental parameter used for SoH definition from manufacturer-specific metrics to a universal energy-based definition. By defining SoH as the ratio of actual energy delivery capacity to nominal energy delivery capacity during fast charging, the method provides a consistent, comparable metric across different battery types and manufacturers, eliminating information loss from inconsistent definitions.
Data Source
AI summary
A method for estimating the State of Health (SoH) of a rechargeable battery. The method may include obtaining a first value of State of Charge of the battery and subjecting the battery to a DC power charging. The method may further include after having performed the DC power charging, obtaining a second value of State of Charge of the battery and computing energy provided to the battery. The method may further include computing the State of Health using the following formula SoH=(DE)/(SoCEND−SoCSTART). In some embodiments, DE may be the energy provided to the battery during the DC power charging, SoCSTART may be the first value of SoC of the battery, and SoCEND may be the second value of SoC of the battery.