Modeling of eddy current transformation of an electromagnetic signal to solve the problem of determining the characteristics of iron ore
DOI:
https://doi.org/10.33216/1998-7927-2025-288-2-68-78Keywords:
electromagnetic transducer, physical parameters, modeling, eddy currentsAbstract
The method of combined electromagnetic transformation for determining the characteristics of ferromagnetic materials is proposed. The method is based on the formation of elastic ultrasonic waves in a rock mass by electromagnetic means and the determination of the parameters of the pulsed eddy current transformation, as well as the amplitude, phase, and frequency of the generated accompanying acoustic signal that has traveled a certain distance in the studied environment. The connection of certain characteristic properties of mineralogical and technological properties of rocks with the parameters of electromagnetic acoustic transformation of sounding signals is proved. The main elements of the model of the eddy-current transformation process as an integral part of the proposed method are considered.
In eddy-current monitoring devices, an AC-driven excitation coil induces an eddy current in the sample through electromagnetic coupling. In turn, the circulation of the eddy current induces a secondary magnetic field. This field will change if the electrical conductivity and magnetic permeability of the sample change. The change in the field is detected by a sensing device, which is either a coil or a magnetic sensor.
The magnetic vector potential and magnetic flux density are calculated using the distributed current source (DCS) method. DCS takes into account eddy currents and magnetization using bulk and surface current sources, which provides closed-form solutions for eddy currents, magnetic flux density, and electromotive force.
The impedance is an important parameter characterizing the frequency response of eddy current sensors. A technology has been investigated that allows, using an optimization procedure for a limited number of segments of the Foster network, to calculate the impedance of the eddy current sensor coil, its resistive and inductive components, and to determine the frequency at which these components are equal to each other. These parameters are characteristic features of the properties of ferromagnetic minerals, in particular, mineralogical and technological types of iron ore. For the practical implementation of this approach, it is proposed to apply the method of intelligent recognition using an adaptive neuro-fuzzy system.
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