Current Sensor Magnetic Field Shaping for Position Shift Tolerance
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Solution Overview
Problem
Current sensors face challenges in accurately measuring magnetic fields when the wire thickness is smaller than the sensor width, leading to significant changes in magnetic flux directions due to slight sensor position shifts, and existing solutions increase sensor size and cost to mitigate this.
Innovation Solution
A current sensor design featuring a wire with a larger width than thickness, a magnetic sensor, and a soft magnetic field shaping member that stabilizes magnetic flux vectors, reducing sensitivity changes even with positional shifts, while maintaining high accuracy and compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic sensor is disposed near a wire to detect magnetic field, then current measurement is enabled, but when wire thickness is smaller than sensor width, magnetic flux direction changes significantly with slight sensor position shifts
Solution Approach 1:
A magnetic field shaping member made of soft magnetic material is introduced as an intermediary between the wire and the magnetic sensor. This member shapes and guides the magnetic flux from the wire toward the sensor, ensuring that even when the sensor position shifts slightly, the magnetic flux vectors entering the sensor maintain consistent directions. The shaping member thus mediates the interaction between the wire and sensor, decoupling the sensor measurement from precise positioning requirements.
2Reliability
If an annular core is used to surround the wire and reduce position shift influence, then measurement stability improves, but sensor size and cost increase
Solution Approach 1:
Instead of using a complete annular core surrounding the wire, the invention employs a segmented approach with a magnetic field shaping member that only occupies the necessary space between the wire and sensor. This partial shaping member provides the required magnetic flux guidance while occupying minimal space, thus achieving position shift tolerance without the bulk and cost of a full annular core structure.
3Measurement precision
If a core with large sectional area is used for high current measurement, then measurement accuracy improves, but device size and cost increase
Solution Approach 1:
The magnetic field shaping member is designed with local quality optimization - it has sufficient magnetic path cross-sectional area only at critical locations where flux concentration is needed (near the wire and at the sensor interface), while being minimized elsewhere. This allows accurate high current measurement without requiring a uniformly large core throughout its entire structure, thus reducing overall device size and cost.
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 design effectively suppresses positional shift influences, allowing for precise magnetic field detection with reduced sensor size and cost, and enables measurement of high currents without significant changes in magnetic flux density.
Implementation Method 1
The magnetic sensor detects a magnetic field generated by a current flowing through the wire
Implementation Method 2
The at least one magnetic field shaping member includes a soft magnetic material and shapes the magnetic field
Data Source
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AI summary
A current sensor 100 includes a wire 110, a magnetic sensor 130, a magnetic field shaping member 140, and a securing member 120. The wire 110 has a thickness in the x direction and a width which is in the z direction perpendicular to the x direction and which is larger than the thickness. The magnetic field shaping member 140 includes a soft magnetic material. The magnetic field shaping member 140 is a plate-shaped member extending substantially parallel to a plane perpendicular to the z direction. The magnetic field shaping member 140 includes a first outer surface 141 facing the magnetic sensor 130. The direction along the first outer surface 141 and the direction of a sensitivity axis of the magnetic sensor 130 are substantially parallel to the x direction. The securing member 120 secures the magnetic sensor 130 and the magnetic field shaping member 140 on the same side in the z direction relative to the wire 110 such that the magnetic sensor 130 and the magnetic field shaping member 140 are located close to each other. The securing member 120 secures the wire 110, the magnetic sensor 130, and the magnetic field shaping member 140 such that the wire 110, the magnetic sensor 130, and the magnetic field shaping member 140 are kept separated from one another in the z direction while the wire 110, the magnetic sensor 130, and the magnetic field shaping member 140 are superposed on one another in the z direction.