Resistive Metallic Fuse Eddy Current Disconnection

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Solution Overview

Problem

Electric vehicle battery systems face challenges in safely and reliably disconnecting circuits when magnetic contactors fail, particularly in high-voltage applications, where a second contactor adds weight, cost, and risk of failure, and existing solutions do not effectively address the risk of circuit damage or safety hazards from stuck switches.

Innovation Solution

A redundant disconnection system using a resistive metallic fuse connected in series with a switch and an inductor, where an AC power source induces eddy currents to melt or vaporize the fuse, ensuring circuit disconnection even if the switch fails to open, thereby preventing damage and ensuring safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a second contactor is added in series to provide redundancy, then circuit disconnection reliability is improved, but device complexity and weight increase

Engineering Contradiction:

Improvecircuit disconnection reliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

An inductor is introduced as an intermediary component between the DC circuit and the fuse. The inductor converts DC current into AC current through electromagnetic induction, enabling the fuse to be actuated without requiring a second DC contactor. This mediator component resolves the contradiction by providing a different mechanism for circuit interruption.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical approach of using a second DC contactor with an electromagnetic field-based approach. The inductor generates an alternating magnetic field that induces AC current in the fuse, substituting mechanical switching with electromagnetic actuation to achieve the same redundancy goal with fewer mechanical components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a second contactor is added in series to provide redundancy, then circuit disconnection reliability is improved, but weight increases

Engineering Contradiction:

Improvecircuit disconnection reliabilityVSAvoidsystem weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The inductor serves as a mediator that transforms the actuation mechanism from mechanical (second contactor) to electromagnetic (induced AC current). This eliminates the need for additional heavy mechanical switching components while maintaining redundancy through the fuse mechanism.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

By replacing the mechanical second contactor with an electromagnetic induction system, the patent significantly reduces system weight. The inductor and fuse combination is lighter than an additional DC contactor assembly, achieving weight reduction while maintaining circuit disconnection reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If existing fuse designs are used in DC circuits, then manufacturing simplicity is maintained, but reliability deteriorates due to inability to clear fused material

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcircuit disconnection reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the electrical parameters applied to the fuse from steady DC current to alternating AC current induced by the inductor. This parameter change causes the fuse to vibrate and clear fused material during operation, improving reliability while maintaining the simplicity of the fuse design and manufacturing process.

Inventive Principle:

Principle #35Parameter changes

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 system effectively and reliably disconnects the circuit by melting or vaporizing the fuse, preventing damage and safety hazards, while reducing weight and cost by eliminating the need for a second contactor, and ensuring rapid disconnection in case of switch failure.

Implementation Method 1

the AC power source may be configured to cause the inductor to induce within the resistive metallic fuse eddy currents of sufficient magnitude to melt or vaporize at least a portion of the resistive metallic fuse

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Implementation Method 3

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS9731606B1Redundant circuit disconnection for electric vehicles

Publication Date: 2017.08.15 FARADAY&FUTURE INC

AI summary

Systems and methods for redundant circuit disconnection in electric vehicles are disclosed. Systems can include a resistive metallic fuse connected within an electrical circuit for a battery or otherwise, an inductor comprising a coil of at least one turn of wire about a longitudinal axis, and an AC power source configured to provide an alternating current across the inductor. The resistive metallic fuse may be disposed within the inductor along the longitudinal axis, and the AC power source may be configured to cause the inductor to induce within the resistive metallic fuse eddy currents of sufficient magnitude to melt or vaporize at least a portion of the resistive metallic fuse disposed therein.