Magnetic Sensor Shield Segmentation for Current Measurement Accuracy
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Solution Overview
Problem
Existing magnetic sensors face challenges in accurately measuring large currents due to limitations in handling strong magnetic fields, which can cause residual magnetization, magnetic saturation, and increased hysteresis, leading to reduced measurement accuracy.
Innovation Solution
A magnetic sensor design featuring a magnetoresistive element, a magnetic shield with a first shield part and second shield parts, and a magnetic balance coil, where the second shield parts form a bypass magnetic path to effectively attenuate perpendicular magnetic fields, thereby enhancing the sensor's tolerance and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic shield is disposed between the current to be measured and the magnetoresistive element to attenuate the induced magnetic field, then the detectable range of magnetic field strength is expanded, but residual magnetization occurs in the magnetic shield causing increased hysteresis and reduced measurement accuracy
Solution Approach 1:
The magnetic shield is divided into a first shield part extending in the in-plane perpendicular direction and second shield parts provided on either side in the longitudinal direction of the first shield part. This segmentation creates multiple magnetic paths that distribute and control the magnetic field attenuation, reducing residual magnetization effects while maintaining shielding effectiveness.
Solution Approach 2:
A magnetic balance coil is introduced as an intermediary element disposed between the magnetoresistive element and the magnetic shield. The coil generates a compensating magnetic field that counteracts the residual magnetization field from the magnetic shield, thereby eliminating hysteresis effects and improving measurement accuracy.
2Object-affected harmful factors
If the distance between the magnetoresistive element and the magnetic shield is reduced to enhance the magnetic field attenuation effect, then the shielding effectiveness is improved, but the strong magnetic field causes magnetic saturation and increased hysteresis in the magnetoresistive element
Solution Approach 1:
The magnetic shield is segmented into first and second shield parts that create distributed magnetic paths. This segmentation allows the shield to effectively attenuate the measurement-target magnetic field while distributing the magnetic flux density to prevent saturation and residual magnetization effects.
Solution Approach 2:
The magnetic balance coil acts as an intermediary that generates a compensating magnetic field to counteract residual magnetization from the magnetic shield, enabling the system to maintain both effective shielding and high measurement accuracy.
3Object-affected harmful factors
If the magnetic shield is made larger to improve shielding coverage, then the magnetic field attenuation is enhanced, but the device complexity and size increase
Solution Approach 1:
The magnetic shield is divided into a first shield part and second shield parts arranged in a specific configuration. This segmentation provides effective shielding coverage for perpendicular magnetic fields while maintaining a compact structure that does not excessively increase device size or complexity.
Solution Approach 2:
The magnetic shield structure utilizes three-dimensional spatial arrangement with the first shield part extending in the in-plane perpendicular direction and second shield parts positioned on either side. This dimensional arrangement achieves effective perpendicular field shielding without requiring excessive planar area.
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 proposed magnetic sensor achieves high tolerance to perpendicular magnetic fields, reducing measurement inaccuracies and maintaining high detection accuracy even under strong magnetic field conditions.
Implementation Method 1
a magnetoresistive element formed in an element formation plane and having a sensitivity axis extending in an in-plane direction
Implementation Method 2
a magnetic shield disposed apart from the magnetoresistive element in a thickness direction perpendicular to the element formation plane and configured to attenuate the strength of the measurement-target magnetic field applied to the magnetoresistive element
Implementation Method 3
a magnetic balance coil disposed between the magnetoresistive element and the magnetic shield, whereby the strength of the measurement-target magnetic field is measured based on a current flowing through the magnetic balance coil
Data Source
AI summary
A magnetic sensor includes a magnetoresistive element having a sensitivity axis in a Y direction, a magnetic shield disposed apart in a Z direction from the magnetoresistive element and configured to attenuate the intensity of a magnetic field to be measured, and a magnetic balance coil. The magnetic shield includes a first shield part longitudinally extending in the X direction and second shield parts provided on either side of the first shield part. The first shield part has a portion that overlaps the magnetoresistive element when viewed in the Z direction. Each second shield part has a portion that overlaps the magnetoresistive element when viewed in the X direction. A magnetic path for a magnetic field in the X direction can be formed from one of the second shield parts to the other one of the second shield parts via the first shield part.