Orthogonal Fluxgate Sensor Cladding and Planar Coils
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Solution Overview
Problem
Conventional orthogonal fluxgate sensors are costly to manufacture, limit miniaturization, and suffer from high perming effects and signal noise due to the use of two ferromagnetic cores and closely coupled planar coils, which complicates the sensor configuration and reduces precision.
Innovation Solution
An orthogonal fluxgate sensor design featuring a non-magnetic excitation conductor clad with saturable magnetic material and integrated pick-up coils, allowing for compact, cost-effective manufacturing and improved signal-to-noise ratio, with the excitation conductor and sensing coils being separately driven and the ferromagnetic cladding ensuring even saturation along its length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If two ferromagnetic cores are used in parallel configuration, then the sensor can be manufactured cost-effectively in large series, but the device complexity increases and occupies more space
Solution Approach 1:
The invention divides the sensor into two independent functional parts: a single ferromagnetic core for excitation and two separate non-magnetic pickup coils for sensing. This segmentation allows each component to be optimized independently, reducing overall complexity while maintaining manufacturability
Solution Approach 2:
The invention combines the excitation function and sensing function into a single integrated sensor head, where the ferromagnetic core serves the excitation function and the pickup coils serve the sensing function, eliminating the need for separate core structures
2Volume of moving object
If planar coils are closely coupled for excitation and detection, then the sensor structure is compact, but the sensor generates huge capacitive and magnetic parasitic signals that deteriorate the signal to noise ratio
Solution Approach 1:
The invention introduces a non-magnetic material as an intermediary between the excitation field and the pickup coils. This intermediary allows the excitation field to pass through without being distorted by the coils, eliminating magnetic parasitic signals while maintaining compact sensor size
Solution Approach 2:
The invention extracts the parasitic magnetic and capacitive effects by using non-magnetic pickup coils that do not interact with the excitation field, separating the useful sensing function from the harmful parasitic interactions
3Length of stationary object
If the core length is shortened to increase measuring range, then the measuring range increases, but the difficulty to generate sufficient magnetic field strength to saturate the core increases
Solution Approach 1:
The invention changes the material parameter from ferromagnetic to non-magnetic for the pickup coils, which eliminates the saturation requirement entirely. This allows the core length to be optimized for measuring range without being constrained by saturation field strength requirements
4Measurement precision
If excitation coil winding is used around the ferromagnetic core, then the orthogonal fluxgate configuration is achieved, but the manufacturing cost increases and miniaturization is limited
Solution Approach 1:
The invention replaces the mechanical winding process with a planar fabrication approach using standard semiconductor metallization techniques. The pickup coils are formed as planar traces on a substrate, eliminating the need for complex 3D winding operations while maintaining the orthogonal fluxgate configuration
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 results in a compact, low-power, high-precision magnetic field sensor with a wide measuring range and reduced perming effect, enabling easy integration into miniaturized electronic devices and adjustable sensitivity and range without significant manufacturing changes.
Implementation Method 1
the excitation of the core and/or the detection of the measured field is performed by the 3D micro machined coils enclosing the core
Implementation Method 2
The working principle of fluxgate sensors based on the periodic saturation of ferromagnetic material with an AC excitation field
Implementation Method 3
detect the change in the flux passing through the core, which is proportional to the external magnetic field
Data Source
AI summary
Orthogonal fluxgate sensor for measuring an external magnetic field Hext, comprising a conductor for carrying an excitation current lexc, a ferromagnetic material adapted to saturate in the presence of a magnetic field generated by the excitation current, and at least one pick-up coil adapted to detect variations in the magnetic field in the vicinity of the magnetic material. The excitation conductor comprises a substantially linear elongated portion of conductive, non-magnetic material, forming an excitation rod (6). The magnetic material surrounds the excitation rod in the form of a cladding (8).