Coupled Parametric Effects on Magnetic Fields of Eddy-Current Induced in Non-Ferrous Metal Plate for Simultaneous Estimation of Geometrical Parameters and Electrical Conductivity

• Published in: IEEE transactions on magnetics Vol. 53; no. 10; pp. 1 - 9
• Main Authors: Lee, Kok-Meng, Lin, Chun-Yeon, Hao, Bingjie, Li, Min
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aluminum; Coils; Conductivity; Conductivity measurement; Conductors; Current measurement; EC testing; Eddy currents; Eddy-current (EC) sensor; electrical conductivity; Electrical resistivity; Finite element method; Flux density; Frequency analysis; Frequency measurement; Frequency ranges; Frequency response; geometrical measurements; Magnetic field measurement; Magnetic fields; Magnetic flux; magnetic frequency response; Magnetism; Material properties; Mathematical models; Metal plates; Nonferrous metals; Parameter estimation; Sensors; Solid modeling; Thickness; Titanium alloys; Titanium base alloys; Two dimensional analysis; Two dimensional models
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2017.2715831

Illustrated with a magnetic field based eddy-current (EC) sensor which utilizes an anisotropic magneto-resistive sensor to directly measure the magnetic flux density (MFD) generated by the EC induced in a non-ferrous metal plate, this paper presents a material-independent method for multi-objective estimation of the plate geometrical parameters and/or electrical conductivity using frequency response analysis. The model, which agrees well with a 2-D axis-symmetric finite-element analysis, relates the measured (EC-generated) MFD to three dimensionless parameters (skin depth, plate thickness, and sensor-plate distance) normalized relative to a specified coil design. Data in the material-independent model that provides the basis to investigate the parametric effects on measured MFD can be regrouped in 2-D maps for simultaneously measuring any two of the three parameters. Experimental measurements were conducted on three different materials (Aluminum, Titanium, and Titanium alloy) with different thicknesses and sensor-plate distances between 1 and 5 mm operating in the frequency range from 100 Hz to 42.8 kHz. Experimental results show that the maximum difference between the analytically computed and experimental data is in the order of 5%, and demonstrate that the method has the capability of simultaneously measuring two unknowns out of three geometrical and/or material properties using a material-independent 2-D map.