Lithium-Ion Capacitor Backup Circuit With Voltage-Based Load Priority

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Solution Overview

Problem

Existing power control circuits using secondary batteries or electric double-layer capacitors fail to provide reliable backup power for extended periods due to self-discharge, limited temperature range, and complexity in managing power distribution to different loads, leading to inefficient and unreliable backup operations.

Innovation Solution

A power control circuit utilizing a lithium-ion capacitor with integrated first and second protection circuits to manage power distribution to different loads based on terminal voltage, ensuring power is prioritized to a secondary load over a predetermined period by controlling current flow through switching elements and regulators, thereby extending backup duration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If conventional secondary batteries are used as backup power sources, then power can be supplied to loads after voltage decreases and discharge stops, but the backup period is limited due to self-discharge and the battery cannot maintain power supply over extended periods

Engineering Contradiction:
Improvebackup periodVSAvoidself-discharge
Core Design Contradiction:
Duration of action of moving objectVSLoss of energy

Solution Approach 1:

The patent changes the energy storage parameter from conventional secondary batteries to lithium-ion capacitors, which have different electrochemical characteristics including lower self-discharge rates and extended operational duration. This parameter change enables the backup power system to maintain power supply for significantly longer periods while reducing energy loss through self-discharge.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If power is supplied to both first load (high power consumption) and second load (low power consumption) simultaneously from the lithium-ion capacitor, then both loads can operate, but the backup period is shortened due to higher total power consumption

Engineering Contradiction:
Improvepower supply to multiple loadsVSAvoidbackup period
Core Design Contradiction:
Ease of operationVSDuration of action of moving object

Solution Approach 1:

The patent implements dynamic power distribution control where the system automatically adjusts power allocation between the first load and second load based on the terminal voltage of the lithium-ion capacitor. When voltage drops below a predetermined threshold, the control unit stops power supply to the first load while continuing to supply the second load, thereby dynamically optimizing the backup period based on real-time power availability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system incorporates voltage detection and control units that continuously monitor the terminal voltage of the lithium-ion capacitor and provide feedback to adjust power distribution. This feedback mechanism enables the system to respond to changing power levels and maintain optimal operation of loads according to available energy reserves.

Inventive Principle:
Principle #23Feedback

3Quantity of substance

If the first protection circuit stops supplying current to the first load at a higher voltage threshold, then more charge remains in the lithium-ion capacitor, but the first load may stop prematurely before completing necessary operations

Engineering Contradiction:
Improvecharge amount in lithium-ion capacitorVSAvoidload operation completion
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent employs dynamic voltage threshold control where the stop voltage for the first load is not fixed but adjusted based on the terminal voltage of the lithium-ion capacitor. The control unit monitors voltage in real-time and dynamically determines when to stop power supply to the first load, ensuring that sufficient charge remains while allowing the load to complete necessary operations before shutdown.

Inventive Principle:
Principle #15Dynamics

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 lithium-ion capacitor-based power control circuit provides stable backup power to both high and low-power loads over an extended period, with reduced self-discharge and wider temperature tolerance, simplifying installation and maintenance, and avoiding unnecessary power consumption.

Implementation Method 1

a lithium-ion capacitor configured to be charged by power supplied by an external power source

Methodology Applied
Scientific EffectElectrochemical energy storage: Battery (electricity)

Data Source

PatentEP3823124B1Power control circuit using a using lithium-ion capacitor as backup power source
Publication Date: 2025.09.03 YOKOGAWA ELECTRIC CORP
  • EP3823124B1 patent drawingFigure 1
  • EP3823124B1 patent drawingFigure 2
  • EP3823124B1 patent drawingFigure 3

AI summary

A power control circuit includes: a lithium-ion capacitor (LIC) charged by power supplied by an power source; a first protection circuit supplying, to a first load operating using power supplied by the external power source, a first discharge current of the LIC when the power is no longer supplied from the power source; and a second protection circuit supplying, to a second load operating using the power, a second discharge current of the LIC when the power is no longer supplied. The second load operates at a lower power consumption than the first load. The first protection circuit stops supplying the first discharge current to the first load when a voltage of the LIC becomes less than a first voltage. The second protection circuit stops supplying the second discharge current to the second load when the voltage becomes less than a second voltage being lower than the first voltage.