Remote Current Sense Eddy-Current Sensor for High-Frequency Inspection
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Solution Overview
Problem
Conventional eddy-current sensors face limitations in high excitation frequencies and long cable lengths due to cable impedance effects, which affect measurement accuracy and restrict the upper bound for inspection frequencies, especially in materials like titanium, nickel superalloys, and non-magnetic stainless steels, and are not suitable for applications such as additive manufacturing.
Innovation Solution
The use of a remote current sense eddy current sensor with separate loop portions for the drive and sense conductors, allowing for local measurement of the drive current through a current sense conductor, which is kept in a known environment to maintain consistent transimpedance, and combining measurements from both the remote current sense and sense element to calibrate results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional eddy-current sensors use long cables to connect the drive signal source to the sensor array, then the sensor can be physically located at a distance from the drive signal generation, but cable impedance effects degrade measurement accuracy and restrict the upper bound for inspection frequencies
Solution Approach 1:
The patent replaces the electrical cable connection system with a wireless communication system. The sensor array transmits measurement data wirelessly to the drive signal source or processing system, eliminating cable impedance effects entirely. This allows arbitrary physical separation while maintaining measurement accuracy at high frequencies, as the wireless transmission is not subject to cable inductance, capacitance, or resistance.
2Measurement precision
If conventional eddy-current sensors operate at high excitation frequencies to improve defect detectability in materials like titanium and nickel superalloys, then inspection sensitivity increases, but cable impedance effects become more severe and limit the usable frequency range
Solution Approach 1:
By replacing the cable-based electrical connection with wireless communication, the system eliminates the frequency-dependent impedance effects that plague high-frequency eddy-current measurements. Wireless transmission does not suffer from cable inductance and capacitance, allowing the sensor to operate at high excitation frequencies needed for detecting defects in challenging materials like titanium and nickel superalloys, while maintaining measurement reliability.
Solution Approach 2:
The patent extracts and removes the cable from the system entirely, separating the drive signal generation from the sensor array operation. The sensor array receives power and transmits data through wireless means, extracting the measurement function from the cable infrastructure that causes impedance problems at high frequencies.
3Measurement precision
If the sensor array is placed close to the material surface to improve measurement sensitivity, then defect detectability increases, but the cable and electronic circuitry become vulnerable to electromagnetic interference and physical damage
Solution Approach 1:
The patent segments the eddy-current inspection system into two independent components: a protected drive signal source located away from the test material, and a minimal sensor array that can be safely positioned close to the material surface. The sensor array contains only the essential sensing elements and wireless transmission capability, separating the vulnerable electronics from the harsh measurement environment while maintaining high measurement sensitivity through close proximity to the material.
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 approach enables accurate measurement at higher excitation frequencies and longer cable lengths, improving detectability of defects in materials like titanium and nickel superalloys, and facilitating inspections in complex environments, such as additive manufacturing.
Implementation Method 1
A time-varying current is applied to the primary winding, which creates a magnetic field that penetrates into the MUT and induces a voltage at the terminals of the secondary elements
Implementation Method 2
This terminal voltage reflects the properties of the MUT
Implementation Method 3
The induced voltage on these sense elements is due to the mutual inductance between each sense element and the drive winding
Data Source
AI summary
An eddy current sensor with a remote current sense has a drive conductor, current sense conductor, and one or more sense conductors. The drive conductor has first and second loop portions, the current sense conductor has a third loop portion, and the sense conductor has a sense loop portion. The first and third loop portions are proximal to each other to form the remote current sense. The sense loop portion and the second loop portion are proximal to each other to form a sense element. The remote current sense and sense element are suitably distant from one another to have separate environments of sensitivity. The sensor may be used by collecting transimpedance measurements from both the remote current sense and sense element under known conditions, and with the sense element under unknown conditions. These measurements are combined to provide a calibrated measurement result suitable for further analysis.