Current Sensor Segmentation for Compact Magnetic Shielding

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Solution Overview

Problem

Current sensors face challenges in maintaining a compact size and low manufacturing cost when measuring large currents due to the increased size of magnetic shield members required for current paths with large cross-sectional areas.

Innovation Solution

The design incorporates an auxiliary current path with a smaller cross-sectional area branching from the main current path, utilizing a magnetic detection element and shield member to measure the auxiliary current, which allows for accurate calculation of the main current while minimizing the size and cost of the sensor by orienting the detection direction orthogonally to the main current's magnetic field.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the magnetic shield member surrounds the main current path to measure large current, then the measurement capability is improved, but the sensor size and manufacturing cost increase

Engineering Contradiction:

Improvemeasurement capabilityVSAvoidsensor size

Core Design Contradiction:

Measurement precisionVSVolume of stationary object

Solution Approach 1:

The current path is segmented into a main current path for carrying large current and an auxiliary current path for measurement. The magnetic shield member only surrounds the auxiliary current path, not the entire main current path, thereby reducing sensor size while maintaining measurement capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An auxiliary current path is introduced as an intermediary element. This auxiliary path carries a scaled-down version of the main current and is surrounded by the magnetic shield member, allowing indirect measurement of the main current without requiring the shield to enclose the large main current path.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the magnetic shield member surrounds the main current path, then the measurement accuracy is improved, but the manufacturing cost increases

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The current path is segmented into a main current path for carrying large current and an auxiliary current path for measurement. The magnetic shield member only surrounds the auxiliary current path, thereby reducing sensor size and manufacturing cost while maintaining measurement capability.

Inventive Principle:

Principle #1Segmentation

3Illumination intensity

If the detection direction is parallel to the main current's magnetic field, then the magnetic field detection is enhanced, but the measurement accuracy decreases due to interference

Engineering Contradiction:

Improvemagnetic field detectionVSAvoidmeasurement accuracy

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

The magnetic detection element is oriented at an asymmetric angle (45 degrees) relative to the main current path, rather than being parallel or perpendicular. This asymmetric orientation allows the detection element to sense the magnetic field while minimizing interference from the main current's magnetic field, improving measurement accuracy.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

Instead of trying to detect the magnetic field in a direction that would be strongly influenced by the main current (parallel direction), the invention uses the auxiliary current path and orients the detection element to detect the magnetic field generated by the auxiliary current, effectively inverting the detection approach to avoid interference.

Inventive Principle:

Principle #13The other way round (Inversion)

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

This configuration enables precise measurement of main currents with reduced sensor size and manufacturing costs by isolating the main current's magnetic field interference and utilizing a miniaturized magnetic shield, enhancing measurement accuracy and preventing magnetic hysteresis-related errors.

Implementation Method 1

a magnetic detection element detecting intensity of a magnetic field in a magnetic detection direction and disposed around a detection target portion which is a part of the auxiliary current path

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 2

a magnetic shield member disposed to surround the detection target portion and the magnetic detection element

Methodology Applied

Scientific EffectMagnetic shielding: Magnetic Field

Data Source

PatentUS10634703B2Current sensor

Publication Date: 2020.04.28 YAZAKI CORP

AI summary

A current sensor includes a main current path in which a main current flows, an auxiliary current path in which an auxiliary current flows, a magnetic detection element detecting intensity of a magnetic field in a magnetic detection direction and disposed around a detection target portion which is a part of the auxiliary current path, and a magnetic shield member disposed to surround the detection target portion and the magnetic detection element. The current sensor is configured to measure a magnitude of the auxiliary current flowing through the detection target portion based on the intensity of the magnetic field detected by the magnetic detection element. The auxiliary current path branches from the main current path and has a smaller cross-sectional area than that of the main current path.