Uncoupled Magnetic Core Current Sensing for Polyphase Fault Detection

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Solution Overview

Problem

Existing current sensors for polyphase electrical systems are bulky, expensive, and prone to electromagnetic interference, making accurate fault detection in compact environments challenging.

Innovation Solution

A current-sensing system with a mechanically uncoupled magnetic sensing element and core, utilizing a magnetic core with an opening to detect the superposition of magnetic fields from multiple conductors, providing a compact and accurate fault detection solution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If wound coils around cores are used for current sensing, then sensitivity is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

ImprovesensitivityVSAvoidcomplexity of manufacture

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the sensing element from direct contact with the magnetic core, using a magnetic core with an opening that allows the sensing element to detect the magnetic field without mechanical coupling. This eliminates the need for complex wound coils while maintaining sensitivity

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The magnetic core with an opening acts as an intermediary that guides and concentrates the magnetic field from the conductors to the sensing element, enabling accurate detection without direct contact or complex winding structures

Inventive Principle:

Principle #24Intermediary (Mediator)

2Volume of moving object

If multiple conductors are enclosed in a compact sensor, then space efficiency is improved, but electromagnetic interference increases

Engineering Contradiction:

ImprovecompactnessVSAvoidelectromagnetic interference

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The magnetic core serves as a mediator that confines and directs the magnetic fields from multiple conductors through a controlled path to the sensing element, reducing electromagnetic interference while maintaining compactness

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The magnetic core is segmented with an opening that separates the flux paths of different conductors, allowing individual field management and reducing interference between adjacent conductors in the compact structure

Inventive Principle:

Principle #1Segmentation

3Stability of the object's composition

If sensing element is in direct contact with magnetic core, then mechanical stability is improved, but thermal drift and mechanical robustness worsen

Engineering Contradiction:

Improvemechanical stabilityVSAvoidthermal and lifetime drift

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The sensing element is extracted from direct contact with the magnetic core, positioned at a distance of at least 0.5 mm away, eliminating thermal conduction paths and mechanical stress transmission while maintaining magnetic field detection capability through the core's opening

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces mechanical coupling between the sensing element and magnetic core with a magnetic field-based detection system, where the sensing element detects the magnetic field through the opening without physical contact, eliminating mechanical and thermal drift issues

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 system offers precise fault detection with improved mechanical robustness, thermal stability, and reduced sensitivity to mechanical displacements, enabling efficient monitoring of polyphase electrical systems.

Implementation Method 1

a sensing element for detecting magnetic field... the sensing element is configured for detecting a component of the superposition of the magnetic field generated through the opening by at least two currents carried by the respective target conductor

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentEP4579248A1Current sensor for monitoring electrical systems

Publication Date: 2025.07.02 MELEXIS TECHNOLOGIES SA

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AI summary

A current-sensing system for fault detection includes a sensing element for detecting a magnetic field and a magnetic core that encloses at least two target conductors. The sensing element is mechanically uncoupled from the magnetic core, and it is designed to detect a component of the magnetic field superposition by currents in the target conductors, the field being generated inside the core and traversing an opening in the core. The sensing element provides an output signal indicative of this superposition. The system is able to detect the combined magnetic field effects of multiple currents, enabling accurate fault detection in electrical systems.