Fluxgate Sensor Air Core Coil Leakage Field Cancellation
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Solution Overview
Problem
Conventional magnetic sensors struggle to accurately measure both DC and AC magnetic fields, especially at high frequencies like 100 kHz, due to limitations in converting magnetic fields into electric signals and ignoring phase relations, leading to errors and noise interference.
Innovation Solution
A magnetic oscillation sensor system with a core-coil and operational amplifier circuit that generates an excitation current for self-magnetization, using an air core coil to cancel leakage magnetic fields and unify oscillation frequencies across sensors, reducing noise and positional gaps for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fluxgate type magnetism detector is used to detect AC magnetic fields, then DC magnetic field detection capability is maintained, but the effective frequency range is limited to a few kHz at maximum
Solution Approach 1:
The invention divides the magnetic field detection task into two independent detection paths: one for DC magnetic fields using a fluxgate sensor, and another for AC magnetic fields up to 100 kHz using a search coil sensor. Each sensor operates optimally within its designated frequency range, avoiding the compromise that limits conventional single-sensor systems.
Solution Approach 2:
The system combines multiple sensor types (fluxgate and search coil) into a single integrated detection device that can universally detect both DC and AC magnetic fields across a wide frequency spectrum (from 0 Hz to 100 kHz), making the device adaptable to various measurement requirements without sacrificing accuracy in any frequency band.
2Ease of operation
If conventional measurement devices display effective values or wave-height values, then simple measurement is achieved, but phase relations among components are ignored causing errors of tens percent
Solution Approach 1:
The system incorporates a phase detection mechanism that monitors the phase relationships among X, Y, and Z magnetic field components. This feedback information is used to correct the synthesis calculation, ensuring that the total magnetic field strength is accurately computed by considering both amplitude and phase relationships, thereby eliminating the tens of percent errors inherent in conventional methods.
3Device complexity
If a single sensor type is used for both DC and AC magnetic field detection, then device complexity is reduced, but detection accuracy across wide frequency range cannot be guaranteed
Solution Approach 1:
The invention segments the detection function into specialized sensors: a fluxgate sensor for DC fields and a search coil sensor for AC fields. This segmentation allows each sensor to be optimized for its specific frequency range, achieving high detection accuracy across the entire spectrum while maintaining manageable system complexity through modular architecture.
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
Enables precise measurement of magnetic fields from a few nT to several mT across a wide frequency range, including up to 100 kHz, with improved accuracy and reduced noise interference, surpassing conventional fluxgate sensors in performance.
Implementation Method 1
an operational amplifier circuit causing an AC excitation current to run through the coil to generate an output in accordance with a strength of a magnetic field applied to the core
Implementation Method 2
a detector for detecting a magnetic field by virtue of non-linear magnetism characteristics of a probe or a sensor including a magnetic core made of a ferromagnetic material
Implementation Method 3
an air core coil wherein the air core coil is positioned in the vicinity of the core-coil of the magnetism sensor, and a current by which a magnetic field having the same strength as that of a leakage magnetic field generated due to an excitation current running through the core-coil
Data Source
AI summary
An apparatus for detecting magnetism includes a self-exciting fluxgate type magnetic oscillation sensor in each of three axes perpendicular to one another, the magnetic oscillation sensor including a magnetism sensor including a core-coil including a core made of a magnetic material and a coil wound around the core, and an operational amplifier circuit causing an AC excitation current to run through the coil to generate an output in accordance with a strength of an external magnetic field applied to the core. An air core coil not wound around a core is arranged in the vicinity of and in parallel with the core-coil of each of the magnetic oscillation sensors arranged in each of the axes.