Vehicle Capacitor SOH Measurement Using ESR and Capacitance
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Solution Overview
Problem
There is a need to accurately evaluate and monitor the State of Health (SOH) of super-capacitors and ultra-capacitors in vehicle applications to prevent premature failure, which can lead to operational issues such as an inability to start an internal combustion engine.
Innovation Solution
A measurement tool and method that perform specific charge and discharge cycles on the capacitor, obtaining current and voltage measurements to calculate Equivalent Series Resistance (ESR) and capacitance, thereby determining the SOH, while considering ambient temperature to optimize charging and discharging processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If charge and discharge cycles are performed to measure capacitor health, then measurement accuracy is improved, but measurement time increases
Solution Approach 1:
The measurement tool performs preliminary characterization of the capacitor component by executing charge and discharge cycles to establish baseline capacitance and ESR values. These preliminary measurements are stored and used as reference for subsequent SOH assessments, enabling rapid evaluation without repeating full characterization cycles each time.
Solution Approach 2:
Instead of performing complete charge and discharge cycles for every measurement, the system uses partial cycles or simplified measurement sequences that capture the essential degradation indicators. This partial action approach maintains sufficient measurement accuracy while significantly reducing the time required compared to full characterization cycles.
2Measurement precision
If multiple parameters (ESR and capacitance) are measured to determine SOH, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The measurement tool combines multiple measurement functions into a single integrated device that can perform both capacitance measurement and ESR measurement, as well as temperature compensation, within one unit. This merging of functions reduces the need for multiple separate instruments while maintaining comprehensive SOH evaluation capability.
Solution Approach 2:
The measurement tool is designed as a universal device capable of measuring multiple parameters (capacitance, ESR, temperature) and evaluating SOH for different types of capacitor components. This multi-functionality allows a single device to replace several specialized instruments, reducing overall system complexity while improving measurement precision through comprehensive parameter assessment.
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 quick and efficient prediction of the capacitor's SOH, enabling pre-emptive maintenance and inventory management, providing users with accurate indications of the capacitor's health and expected replacement time.
Implementation Method 1
the charging and discharging is performed further based on the ambient temperature surrounding the capacitor component. Since the ambient temperature surrounding capacitor component will affect its ability to store voltage, this means that the ambient temperature is used to optimize the charging and discharge cycles of the capacitor component
Implementation Method 2
determining an Equivalent Series Resistance, ESR, and a capacitance of the capacitor component based on the obtained current and voltage measurements
Data Source
AI summary
The disclosure relates to a method performed by a measurement tool for determining a State of Health, SOH, of a capacitor component in a vehicle, wherein the method comprises performing charging and discharging of the capacitor component according to a specific determined charge and discharge cycle; obtaining current and voltage measurements during both the charging and discharging of the capacitor component; determining an Equivalent Series Resistance, ESR, and a capacitance of the capacitor component based on the obtained current and voltage measurements; and determining the SOH of the capacitor component based on the determined capacitance and ESR.