Electromagnetic Induction Calibration Using Metrological Coil Coupling
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Solution Overview
Problem
Existing electromagnetic induction methods for determining physical parameters of electrically conductive media face challenges in accurately calibrating the ratio of magnetic secondary to primary fields due to errors in calculating the calibration factor, which are exacerbated by the need for precise coil geometries and distances, leading to inefficiencies and inaccuracies.
Innovation Solution
An indirect calibration method involving a two-stage process where the calibration factor is determined metrologically through measured mutual inductance between a calibration coil and receiving coil, using a series connection with a changeable resistor, allowing for precise calibration without complex calculations and enabling a compact measuring assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the calibration factor is calculated computationally from coil geometries and distances, then the calibration process can be performed, but measurement precision deteriorates due to errors in determining coil distances and geometries
Solution Approach 1:
The patent replaces the computational calculation method (based on mechanical measurements of coil geometries and distances) with an electrical measurement method. A test signal is applied to the calibration coil, and the induced voltage in the receiving coil is measured electrically. This substitution of electrical measurement for mechanical calculation eliminates errors associated with determining coil distances and geometries, thereby improving calibration factor precision while maintaining ease of calibration.
Solution Approach 2:
The patent introduces a test signal as an intermediary to transfer the calibration information. Instead of directly calculating the calibration factor from physical dimensions, a known test signal is applied to the calibration coil, and the response is measured in the receiving coil. This intermediary signal allows the calibration factor to be determined through electrical measurement rather than computational calculation, improving precision.
2Reliability
If a separate calibration coil is installed in the measuring assembly, then calibration can be performed, but device complexity increases
Solution Approach 1:
The calibration coil in the patent is designed to serve multiple functions: it acts as both a calibration element and an integral part of the measuring assembly. By making the calibration coil permanently installed and inductively coupled with the receiving coil, it becomes a universal component that participates in both calibration operations and normal measurements, thereby reducing overall device complexity while maintaining calibration capability.
Solution Approach 2:
The patent merges the calibration coil with the receiving coil system through permanent inductive coupling. Instead of treating them as separate, independent components, the calibration coil is integrated into the measuring assembly structure, sharing space and functional pathways with the receiving coil. This merging reduces the number of discrete components and simplifies the overall device 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
This method reduces errors in determining the calibration factor, enhances accuracy, and allows for a more compact and flexible measuring assembly, suitable for applications like sea ice thickness measurement in geophysics.
Implementation Method 1
a calibration pulse, generated in the calibration coil, inducing a calibration field (HCx), which induces a magnetic flux in the receiving coil
Implementation Method 2
In the electromagnetic induction method, the effect is utilized that eddy currents are induced by strong magnetic alternating fields in a conductive medium. These eddy currents are the cause of secondary magnetic fields
Implementation Method 3
a receiving coil is arranged. This receiving coil detects the secondary field emitted from the medium at the substrate and converts it into a voltage
Data Source
AI summary
An indirect calibration method for an electromagnetic induction method for determining physical parameters of an electrically conductive medium from a ratio (HS/HP) of a magnetic secondary field (HS), received in a receiving coil, to a magnetic primary field (HP) emitted from a transmitting coil electrically connected to a transmission signal generator, in which as measurement for the ratio (HS/HP) a received voltage (URx) is measured at an output of a receive amplifier electrically connected to the receiving coil, which is calibrated by series connection of at least one calibration coil and of a changeable calibration resistor and of a calibration factor (HCx/HP) which is adjustable therethrough, the receiving coil being permanently inductively coupled with the calibration coil, a calibration pulse, generated in the calibration coil, inducing a calibration field (HCx), inducing a magnetic flux in the receiving coil, areas and winding numbers of the receiving and calibration coils being known.