Supercapacitor Charge Voltage Control Using Capacitance Aging Feedback
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Solution Overview
Problem
Super capacitors in building management systems face a tradeoff between energy storage and lifespan, with high operating voltages increasing energy storage but shortening lifespan, while lower voltages prolong lifespan but reduce energy storage, and there is a lack of effective methods to determine optimal charging voltages and monitor capacitor health.
Innovation Solution
A method and system for determining the lifetime of super capacitors by measuring energy requirements and effective capacitance, adjusting charge voltage based on these measurements, and providing indications for replacement, which includes a processing circuit in a failsafe device assembly to manage the charging and operation of super capacitors in building management systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If super capacitors are operated at rated voltage, then energy storage is increased, but operating life is shortened
Solution Approach 1:
The patent applies dynamics by making the charge voltage adjustable rather than fixed. The system dynamically adapts the charge voltage based on the super capacitor's age and condition, transitioning from higher voltages when new to lower voltages as it ages. This dynamic adjustment resolves the contradiction by allowing the system to optimize between energy storage and operating life at different stages of the capacitor's lifecycle.
Solution Approach 2:
The patent changes the operating parameter (charge voltage) based on the super capacitor's condition and age. By monitoring capacitance degradation and adjusting the charge voltage accordingly, the system resolves the contradiction between maximizing energy storage at rated voltage and extending operating life through lower voltage operation. The parameter change is implemented through a controller that modifies the charging profile based on measured capacitance values.
2Duration of action of stationary object
If super capacitors are operated at lower voltage, then operating life is prolonged, but energy storage is decreased
Solution Approach 1:
The system dynamically adjusts the charge voltage based on the super capacitor's age and condition rather than using a fixed low voltage. This allows the system to maximize energy storage at each stage of the capacitor's life while still protecting it from excessive stress. The dynamic approach resolves the contradiction by avoiding unnecessarily low voltages when the capacitor is still healthy.
Solution Approach 2:
The patent implements preliminary action by measuring the super capacitor's capacitance and determining its remaining life before final failure occurs. This early detection allows the system to proactively adjust the charge voltage to extend operating life while maintaining adequate energy storage. The preliminary assessment of capacitor health enables preventive voltage reduction before the capacitor fails.
3Quantity of substance
If charge voltage is increased to maximize energy storage, then capacitance degradation is accelerated, but if charge voltage is reduced to slow degradation, then energy storage capacity is reduced
Solution Approach 1:
The patent implements feedback by continuously monitoring the super capacitor's capacitance and using this information to adjust the charge voltage. The controller measures the capacitance, compares it to the rated value, and adjusts the charging profile accordingly. This feedback loop resolves the contradiction by automatically reducing voltage when capacitance degradation is detected, preventing further acceleration of degradation while maintaining adequate energy storage.
Solution Approach 2:
The system performs self-service by autonomously monitoring its own health status and adjusting its operating parameters without external intervention. The super capacitor system measures its own capacitance, determines its remaining life, and self-regulates the charge voltage to optimize both energy storage and reliability. This self-service capability resolves the contradiction by enabling the system to adapt to its own aging process.
Data Source
AI summary
A method of determining a lifetime parameter of a capacitor in a failsafe device including measuring an amount of energy required to return the failsafe device to a failsafe position, measuring an effective capacitance of the capacitor, and comparing the amount of energy to the effective capacitance to determine the lifetime parameter of the capacitor.