Fluxgate Sensor Dual-Core Magnetic Circuit Design
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Solution Overview
Problem
Existing fluxgate magnetic sensors with open magnetic circuit structures require a large number of windings for sufficient inductance, limiting their downsizing potential, and those with closed magnetic circuits have a narrow measurement range due to saturation flux density limitations.
Innovation Solution
A fluxgate magnetic sensor with a closed magnetic circuit structure using a first core made of a soft magnetic material that reaches magnetic saturation at a higher field intensity than a second core, allowing the coil to be wound around the first core, maintaining magnetic characteristics even when the second core is saturated, and enhancing sensitivity and measurement range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a closed magnetic circuit structure is used, then inductance is improved, but measurement range deteriorates due to saturation flux density limitations
Solution Approach 1:
The magnetic circuit is divided into two separate cores: a first core made of ferrite material and a second core made of amorphous magnetic metal. These cores are connected to form a closed magnetic circuit structure. The segmentation allows each core to contribute different magnetic properties, enabling the system to achieve both high inductance and wide measurement range by combining the advantages of different materials.
Solution Approach 2:
The patent uses composite magnetic circuit structure combining ferrite (first core) and amorphous magnetic metal (second core). The ferrite core provides high resistance to magnetic saturation, while the amorphous magnetic metal core provides high magnetic permeability. This composite approach allows the magnetic sensor to maintain high inductance from the closed magnetic circuit while extending the measurement range beyond what a single material could achieve.
2Volume of moving object
If the coil is wound around the low resistance portion made of permalloy, then inductance is improved, but measurement range deteriorates due to saturation flux density
Solution Approach 1:
Different portions of the magnetic circuit are assigned different materials with optimized properties for specific functions. The first core (ferrite) is optimized for high resistance to saturation, while the second core (amorphous magnetic metal) is optimized for high magnetic permeability. The coil is wound around the first core, which has higher saturation flux density, thereby avoiding the saturation limitation that would occur if the coil were wound around the second core alone.
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 solution provides a fluxgate magnetic sensor with high inductance and a wide measurement range, enabling sensitive detection across a broader magnetic field intensity range while maintaining cost-effectiveness through the use of commonly available materials like ferrite and amorphous magnetic metals.
Implementation Method 1
The first core and the second core form a closed magnetic circuit structure
Implementation Method 2
a coil that is wound around the first core between the first connection surface and the second connection surface
Implementation Method 3
The first core reaches magnetic saturation at a higher magnetic field intensity than that of the second core
Implementation Method 4
the second core has a higher magnetic permeability than that of the first core
Data Source
Figure 1A~1C
Figure 2~3
Figure 4~5
AI summary
Disclosed herein is a magnetic sensor including: a first core made of a first soft magnetic material, the first core having first and second connection surfaces; a second core made of a second soft magnetic material different from the first soft magnetic material, the second core having a third connection surface facing the first connection surface and a fourth connection surface facing the second connection surface; and a coil wound around the first core between the first connection surface and the second connection surface. The first core reaches magnetic saturation at a higher magnetic field intensity than that of the second core, and the second core has a higher magnetic permeability than that of the first core.