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Quantifying the Relative Thickness of Conductive Ferromagnetic Materials Using Detector Coil-Based Pulsed Eddy Current Sensors
Published on: January 16, 2020
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Time-domain modeling analysis of pulsed eddy current testing on ferromagnetic casing
Hu Sun1, Yibing Shi1, Wei Zhang1
1School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.
The Review of Scientific Instruments
|October 2, 2020
Summary
This study introduces a voltage-driven pulsed eddy current method for ferromagnetic material evaluation, overcoming signal distortion issues common in current-driven systems. The new approach offers improved signal stability and accuracy in testing.
Area of Science:
- Materials Science
- Electromagnetism
- Non-Destructive Testing
Background:
- Pulsed eddy current (PEC) testing is valuable for ferromagnetic materials due to low power needs and broad frequency spectra.
- Current-driven PEC systems face challenges with driver coil inductance, causing reverse electromotive force and signal distortion.
- Existing excitation circuits struggle to meet power and stability demands for counteracting this reverse electromotive force.
Purpose of the Study:
- To investigate a pulsed eddy current field generated by a voltage-driven coil for ferromagnetic casing evaluation.
- To formulate analytic solutions for the voltage-driven pulsed eddy current field.
- To analyze and address the limitations of current-driven PEC methods.
Main Methods:
- Developing a theoretical model for a voltage-driven pulsed eddy current system with concentric coils.
- Formulating analytic solutions for the induced electromotive force in pick-up coils using the superposition principle.
- Analyzing the electromotive force induced by coil inductance and eddy currents.
- Adopting a novel pulse excitation function for improved signal generation.
Main Results:
- The study presents analytic solutions for the voltage-driven pulsed eddy current field.
- It analyzes the electromotive force generated by coil inductance and eddy currents, contrasting with current-driven methods.
- Theoretical findings were validated through experimental verification.
Conclusions:
- A voltage-driven pulsed eddy current approach offers a viable alternative to current-driven methods for ferromagnetic material evaluation.
- This method effectively mitigates signal distortion issues caused by reverse electromotive force.
- The developed analytic solutions and experimental validation confirm the efficacy of the proposed technique.
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