Gradient Magnetic Field Sensor Sensitivity Equalization
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Solution Overview
Problem
Gradient magnetic field sensors with two sensor heads often have individual differences in sensitivity, leading to false detection of magnetic field gradients within uniform magnetic field areas, which reduces detection accuracy for target objects.
Innovation Solution
A gradient magnetic field sensor configuration that includes an AC power supply connection terminal, first and second magnetic cores, an AC current control unit, detection coils, and a detection circuit. The AC current control unit adjusts the AC current flowing through the magnetic cores to control the sensitivity of the detection coils, ensuring they are differentially connected to cancel out uniform magnetic field components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two sensor heads are used to detect magnetic field intensities at two different points, then the gradient magnetic field sensor can detect the gradient of intensities of magnetic fields, but the sensor frequently detects false gradients inside uniform magnetic field areas due to individual differences in sensitivity between the two sensor heads
Solution Approach 1:
The patent applies parameter changes by adjusting the excitation current for each sensor head individually. The excitation current adjustment unit modifies the AC excitation current supplied to each sensor head based on its detected sensitivity, thereby equalizing the sensitivity of both sensor heads and eliminating false gradient detections in uniform magnetic field areas.
Solution Approach 2:
The patent implements feedback through the sensitivity detection and adjustment mechanism. The sensitivity detection unit continuously monitors the output of each sensor head, and the excitation current adjustment unit uses this feedback information to modulate the excitation current, creating a closed-loop system that maintains balanced sensitivity between sensor heads.
2Measurement precision
If DC excitation currents are adjusted to equalize sensitivities of two sensor heads, then detection accuracy improves, but the device complexity increases due to additional control circuits
Solution Approach 1:
The patent applies universality by designing the excitation current adjustment unit to serve multiple functions: it adjusts excitation current for sensitivity equalization, compensates for individual differences between sensor heads, and maintains optimal detection performance. This multi-functional approach reduces the need for separate dedicated circuits for each function.
Solution Approach 2:
The system implements self-service through automated sensitivity detection and self-adjustment of excitation currents. The sensitivity detection unit continuously monitors sensor head performance, and the excitation current adjustment unit autonomously modulates the excitation current without external intervention, enabling the system to self-optimize its detection accuracy.
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
This configuration improves the accuracy of detecting target objects using magnetic fields by preventing false gradients from uniform magnetic field areas, thereby enhancing the sensor's detection precision.
Implementation Method 1
a detection coil in which a voltage is induced in accordance with a magnetic field generated from the magnetic core
Data Source
AI summary
A gradient magnetic field sensor includes: an AC power supply connection terminal to which a first power supply terminal included in an AC power supply is connected; a first magnetic core connected between the connection terminal and the ground; a second magnetic core connected in parallel with the first magnetic core between the connection terminal and ground; an AC current control unit connected between the connection terminal and at least one of the first magnetic core and the second magnetic core and configured to control an AC current flowing through at least one of the first and second magnetic core; a first detection coil wound around the first magnetic core; a second detection coil wound around second magnetic core and differentially-connected with the first detection coil; and a detection circuit that detects a voltage difference between first voltage output from first detection coil and second voltage output from the second.