Inductive Magnetic Sensor Circuit for Ultra-Low Frequency Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inductive magnetic sensors face limitations in expanding low-frequency bandwidth and achieving high sensitivity for ultra-low frequency signals due to low effective permeability and high noise levels at low frequencies, making them inconvenient for field applications.
Innovation Solution
The design incorporates a signal pre-amplifying measurement circuit with resonant notch filters and a low-noise autozero processing circuit, along with a magnetic core and coil group, to extend the low-frequency characteristics and improve signal-to-noise ratio by moving the resonant frequency to lower ranges and incorporating capacitors for noise suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the length-to-diameter ratio of the magnetic core is increased to improve effective permeability, then sensitivity is improved, but the device becomes inconvenient for field work due to increased size
Solution Approach 1:
The patent changes the resonant frequency parameter of the measurement coil to extend the passband to low frequencies. By adjusting the resonant frequency to be lower than the lower cutoff frequency of the passband, the system achieves both high sensitivity and extended low-frequency response without requiring an increased magnetic core length-to-diameter ratio
Solution Approach 2:
The patent introduces a switchable capacitor that can be connected or disconnected based on the measurement frequency range. This dynamic adjustment allows the resonant frequency to be optimized for different operating conditions, enabling the system to maintain high sensitivity across both low-frequency and higher-frequency measurements
2Reliability
If magnetic flux feedback is introduced to suppress quality factor at resonant frequency for system stability, then stability is improved, but sensitivity for ultra-low frequency signals becomes extremely low
Solution Approach 1:
The patent dynamically switches the feedback loop on or off based on the measurement frequency. For ultra-low frequency measurements, the feedback loop is turned off to maintain high sensitivity. For higher frequency measurements where stability is critical, the feedback loop is activated to suppress resonant peaks. This dynamic control resolves the contradiction between stability and sensitivity
3Reliability
If the resonant frequency of the coil is kept high to ensure system stability, then stability is improved, but the passband cannot be extended to low frequencies
Solution Approach 1:
The patent changes the resonant frequency parameter from a fixed high value to a switchable configuration. By using a switchable capacitor, the resonant frequency can be adjusted to match the measurement requirements. When measuring low frequencies, the capacitor is connected to lower the resonant frequency and extend the passband. When measuring higher frequencies, the capacitor is disconnected to maintain higher resonant frequency for stability
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 enhances the low-frequency magnetic sensor's performance by extending its passband, reducing noise, and increasing gain without saturation, making it more suitable for field work and reducing the sensor's volume and weight.
Implementation Method 1
An inductive magnetic sensor (hereinafter referred to as a magnetic sensor) is a device based on the Faraday's law of electromagnetic induction, which uses a direct-proportion relationship between an output voltage of a coil and a change amount of magnetic flux passing through the coil
Implementation Method 2
a feedback coil wound on the magnetic core, configured to generate a counteracting magnetic flux to suppress the resonant frequency effects
Data Source
AI summary
The present disclosure provides an inductive magnetic sensor, which includes a signal pre-amplifying measurement circuit, a feedback loop, a magnetic core and coil group, a low-noise autozero processing circuit, and an output protection module. The magnetic core and coil group is electrically connected between the signal pre-amplifying measurement circuit and the feedback loop, the signal pre-amplifying measurement circuit comprises the low-noise autozero processing circuit, and the feedback loop and the low-noise autozero processing circuit are electrically connected to the output protection module respectively. By introducing the resonant notch filter, it may extend the passband to the low frequency, and extend the low-frequency characteristic of the magnetic sensor, to obtain a better low-frequency magnetic sensor. The present disclosure further provides an electromagnetic prospecting equipment.