Solid-State Disconnect Circuit for Arc-Free Fault Isolation

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Solution Overview

Problem

Conventional contactor systems for overcurrent protection in electrical circuits, such as those used in electric vehicles, suffer from issues like arcing, device degradation, and increased maintenance costs due to their mechanical nature, and existing arc quenching techniques are large, heavy, and costly, failing to provide adequate protection to connected systems.

Innovation Solution

A solid-state disconnect apparatus with a solid-state disconnect electronic component and a sensor is used to detect fault conditions, such as short circuits or current surges, and rapidly disconnect operational components from the power source, utilizing a solid-state switch like IGBT or MOSFET to provide fast and reliable protection, with a response time of less than 10 microseconds for let-through currents ranging from 100 to 1200 amperes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional contactor systems are used for overcurrent protection, then current switching capability is achieved, but arcing and device degradation occur reducing reliability

Engineering Contradiction:

Improvedevice reliabilityVSAvoidarcing

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces mechanical contactors with solid-state electronic switches (MOSFETs or IGBTs) that perform current switching without mechanical moving parts. This substitution eliminates contact erosion and arcing problems inherent in mechanical systems, achieving reliable protection against overcurrent conditions while maintaining fast response capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If conventional arc quenching techniques are used, then arcing is suppressed, but device size and weight increase

Engineering Contradiction:

Improvearcing suppressionVSAvoiddevice weight

Core Design Contradiction:

Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

The patent eliminates the need for arc quenching techniques by replacing mechanical contactors with solid-state switches. Since solid-state devices have no mechanical contacts, there is no arc generation requiring suppression, thereby avoiding the additional weight and complexity of arc quenching mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If conventional contactor systems are used, then current switching is achieved, but maintenance costs increase

Engineering Contradiction:

Improveswitching operationVSAvoidmaintenance cost

Core Design Contradiction:

ProductivityVSEase of repair

Solution Approach 1:

The patent replaces mechanical contactors with solid-state electronic switches that have no wear parts. This eliminates the need for maintenance associated with contact erosion and mechanical wear, significantly reducing maintenance costs while maintaining full switching capability for overcurrent protection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Loss of time

If solid-state disconnect component is used, then response time is reduced, but device complexity increases

Engineering Contradiction:

Improveresponse timeVSAvoiddevice complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent uses solid-state switches (MOSFETs or IGBTs) controlled by microcontrollers or protection circuits that can detect overcurrent conditions and switch within microseconds. While the electronic control circuitry adds complexity, it enables response times less than 10 milliseconds, far faster than mechanical contactors, and the complexity is justified by the significant performance improvement.

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 solid-state solution provides enhanced reliability, reduced maintenance costs, and fast recovery from false triggers, while minimizing arcing and device degradation, offering efficient short-circuit protection and controlled pre-charge functionalities without the need for mechanical parts.

Implementation Method 1

utilizing a solid-state switch like IGBT or MOSFET to provide fast and reliable protection, with a response time of less than 10 microseconds

Methodology Applied

Scientific EffectSolid state switching:

Implementation Method 2

a sensor coupled to the solid-state disconnect electronic component. The solid-state disconnect electronic component may be configured to disconnect an operational electronic component from a power source upon the sensor detecting a fault condition

Methodology Applied

Scientific EffectElectrical sensing:

Data Source

PatentUS20250286361A1Protection and sensing systems and methods

Publication Date: 2025.09.11 LITTELFUSE INC

AI summary

A circuit protection apparatus. The apparatus includes a solid-state disconnect electronic component, and a sensor coupled to the solid-state disconnect electronic component. The solid-state disconnect electronic component is configured to disconnect an operational electronic component and a power source upon the sensor detecting a fault condition.