Capacitor Charge Voltage Adjustment for Aging Compensation
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Solution Overview
Problem
Electrochemical double layer capacitors (EDLCs) have a limited lifetime due to aging caused by temperature and voltage, which accelerates electrochemical reactions, reducing capacitance and conductance, and existing solutions like cooling require bulky fans that are not suitable for all environments.
Innovation Solution
A method to adjust the charge voltage of capacitors based on their capacitance and required energy level, ensuring the stored energy remains constant, thereby compensating for aging and extending the capacitor's lifetime, while also considering ohmic voltage drops and temperature influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the charge voltage is kept constant to simplify the control system, then the system complexity is reduced, but the energy stored in the capacitor decreases over time due to aging, causing the capacitor to fail to meet the required energy level
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant voltage charging approach to a dynamic voltage adjustment approach. The control unit continuously monitors the capacitance value and adjusts the charge voltage accordingly to maintain constant stored energy, ensuring the energy level requirement is met throughout the capacitor's lifetime while adapting to aging effects.
Solution Approach 2:
The patent implements feedback by having the control unit receive real-time capacitance values from the capacitor and use this information to adjust the charge voltage. This closed-loop feedback mechanism ensures that the stored energy remains constant despite capacitance degradation, maintaining reliability without excessive system complexity.
2Reliability
If a high initial capacitance is used to ensure sufficient energy storage throughout the capacitor's lifetime, then the required energy level is maintained, but the capacitor size, cost, and charging time increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the charge voltage based on the capacitor's aging state. Instead of using a large capacitor with fixed parameters, the system changes the voltage parameter over time to compensate for capacitance degradation, maintaining the required energy level with a smaller, faster-charging capacitor.
3Reliability
If the charge voltage is increased to compensate for capacitance loss and maintain energy level, then the required energy is maintained, but the aging of the capacitor is accelerated
Solution Approach 1:
The control unit uses feedback to monitor capacitance changes and adjusts the charge voltage in a controlled manner. This prevents excessive voltage increases that would accelerate aging, while still maintaining the required energy level by optimizing the voltage based on actual capacitance measurements.
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
The method effectively maintains the energy level above the required level, slows down aging, and reduces charging time, thereby increasing the capacitor's lifespan and efficiency.
Implementation Method 1
The energy stored in a capacitor Wstored is proportional to the capacitance value and to the square of the voltage across the capacitor
Implementation Method 2
The aging of the EDLCs is influenced by temperature and voltage. Increasing the voltage and temperature will exponentially accelerate the electrochemical reactions and thus leading to a decrease in capacitance and conductance
Implementation Method 3
receiving a conductance value of the capacitor, said conductance value being related to an ohmic voltage drop
Data Source
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AI summary
There is provided a method and arrangements for adjusting a charge voltage of a capacitor which is used as a power back-up in a system having a required energy level. The method comprises adjusting the charge voltage of the capacitor based on a received capacitance value and a received value of the required energy level. The adjustment is performed such that an energy level stored in the capacitor is kept essentially constant. The invention is advantageous in that it extends the lifetime of the capacitor.