Electric Field Current Limiter for Fast Inrush Protection

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Solution Overview

Problem

Existing protection devices for integrated circuits and electrically conductive devices are inadequate in responding to various undesirable power conditions, such as current inrush and surges, leading to potential damage and the need for larger components to compensate, which results in inefficiencies and increased costs.

Innovation Solution

A current limiter is introduced, configured as a fast-response device using an electric field activated by voltage differences between a power source and a load terminal, comprising a switch and control circuit that transitions between non-current-limiting and current-limiting states to manage current effectively, independent of temperature changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protection device is used to protect integrated circuits from power conditions, then protection is provided, but the device may not respond to each type of undesirable power condition (current in-rush, current surge) adequately

Engineering Contradiction:
Improveprotection capabilityVSAvoidresponse to various power conditions
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The protection function is divided into two separate devices: a fast-response current limiter that responds to current in-rush and surge conditions, and a slower-acting protection device that handles other power conditions. This segmentation allows each device to be optimized for its specific function, improving overall system reliability and adaptability to different power conditions.

Inventive Principle:
Principle #1Segmentation

2Reliability

If protection devices are added to compensate for inadequacies in response to certain power conditions, then protection is improved, but device size and complexity increase

Engineering Contradiction:
Improveprotection adequacyVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the fast-response current limiting function with the overall protection device into a single integrated unit. The current limiter is configured to operate in conjunction with the protection device, creating a unified system that provides both fast response to current in-rush/surge conditions and protection against other power conditions, thereby reducing the need for multiple separate components.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If larger components are used to compensate for protection device inadequacies, then protection is improved, but device weight and size increase

Engineering Contradiction:
Improveprotection levelVSAvoiddevice weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The current limiter changes the response time parameter of the protection system by introducing a very fast response mechanism that operates independently of thermal effects. This allows the use of smaller, lighter components since the fast-response current limiter handles the most critical transient conditions that would otherwise require oversized protection components.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If traditional protection devices are used, then protection is provided, but response time to current in-rush and surge is slow

Engineering Contradiction:
Improveprotection functionVSAvoidresponse time
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The patent replaces thermal-based protection mechanisms with an electric field-based current limiting mechanism. The current limiter uses an electric field to detect and respond to current in-rush and surge conditions almost instantaneously, eliminating the delay inherent in thermal-based protection devices that rely on temperature changes to trigger protection.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 current limiter provides rapid and effective current limitation, reducing the need for additional protection components, enhancing efficiency and reducing the size and weight of devices while maintaining protection across varying temperatures.

Implementation Method 1

The current limiter is configured to limit, as a fast-response current limiter, a current from the power source terminal to the load terminal using an electric field activated in response to a difference in voltage between the power source terminal and the load terminal

Methodology Applied
Scientific EffectElectric field: Electric Field

Data Source

PatentEP2779346B1Methods and apparatus including a current limiter
Publication Date: 2020.05.27 FAIRCHILD SEMICON CORP
  • EP2779346B1 patent drawingFigure 1A~1C
  • EP2779346B1 patent drawingFigure 2
  • EP2779346B1 patent drawingFigure 3A~3B

AI summary

In one general aspect, an apparatus can include a load terminal, and a power source terminal. The apparatus can include a current limiter coupled to the load terminal and coupled to the power terminal. The current limiter can be configured to limit a current from the power source terminal to the load terminal using an electric field activated in response to a difference in voltage between the power source terminal and the load terminal.