Current Sensor Magnetic Shield Segmentation for Disturbance Rejection

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Solution Overview

Problem

Current sensors in vehicles, such as those in hybrid electric vehicles, face challenges in maintaining measurement accuracy due to the influence of disturbance magnetic fields, which can lead to degradation in output linearity and detection accuracy.

Innovation Solution

The implementation of a current sensor design that includes a magnetic detector and a magnetic shield, where the magnetic shield surrounds the detector and is spaced from both the conductor and the detector, effectively mitigating the impact of disturbance magnetic fields by splitting and canceling out unwanted magnetic flux components, while allowing the primary magnetic flux to reach the detector.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a magnetic sensor is placed close to a conductor to detect current, then detection sensitivity is improved, but the sensor is more affected by disturbance magnetic fields

Engineering Contradiction:

Improvecurrent detection accuracyVSAvoiddisturbance magnetic field influence

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A magnetic shield body is introduced as an intermediary between the magnetic sensor and external disturbance magnetic fields. The shield body includes a first magnetic shield portion and a second magnetic shield portion that work together to block disturbance magnetic fields from reaching the sensor, while allowing the sensor to remain positioned for effective current detection.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The magnetic shield body is divided into multiple segments (first magnetic shield portion and second magnetic shield portion) rather than using a single continuous shield. This segmentation allows the shield to effectively block disturbance magnetic fields from multiple directions while maintaining space for the conductor and sensor positioning.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If a magnetic shield is placed close to the magnetic detector to block disturbance fields, then shielding effectiveness is improved, but the detector is blocked from the primary magnetic flux

Engineering Contradiction:

Improvedisturbance magnetic field influenceVSAvoidmagnetic flux detection accuracy

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The magnetic shield portions are strategically positioned to provide localized shielding only in directions where disturbance magnetic fields originate, while leaving the path from the conductor to the sensor open. The first and second magnetic shield portions are arranged to shield from specific directions without blocking the primary magnetic flux generated by the conductor.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The magnetic shield body is configured in a three-dimensional arrangement around the conductor and sensor, with shield portions extending in different spatial dimensions. This allows the shield to block disturbance fields from multiple directions simultaneously while maintaining the magnetic flux path from the conductor to the sensor in a different spatial plane.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 design enhances the accuracy of current measurement by reducing the influence of disturbance magnetic fields, preventing magnetic saturation of the flux concentrating core, and maintaining high measurement precision.

Implementation Method 1

a magnetic detector configured to be subjected to a magnetic flux that is to be generated when a current flows through a conductor along a first axis direction, the magnetic flux being in a second axis direction

Methodology Applied

Scientific EffectMagnetic flux detection: Hall Effect

Implementation Method 2

a first soft magnetic body including a first portion, a second portion disposed between the conductor and the first portion, and a third portion magnetically coupling the first portion and the second portion to each other

Methodology Applied

Scientific EffectMagnetic coupling: Magnetic Field

Implementation Method 3

The first soft magnetic body is spaced from both of the conductor and the magnetic detector, with the first portion, the second portion, and the third portion surrounding the magnetic detector

Methodology Applied

Scientific EffectMagnetic saturation prevention: Magnetic Saturation

Data Source

PatentUS11543469B2Current sensor, and electric control apparatus including the current sensor

Publication Date: 2023.01.03 TDK CORP

AI summary

A current sensor includes a magnetic detector and a first soft magnetic body. The magnetic detector is configured to be subjected to a magnetic flux that is to be generated when a current flows through a conductor along a first axis direction, the magnetic flux being in a second axis direction. The first soft magnetic body includes a first portion, a second portion disposed between the conductor and the first portion, and a third portion magnetically coupling the first portion and the second portion to each other. The first soft magnetic body is spaced from both of the conductor and the magnetic detector, with the first portion, the second portion, and the third portion surrounding the magnetic detector along a first plane orthogonal to the second axis direction.