Expanding the functional capabilities of an electromagnetic converter with a spatially periodic magnetic field structure

Abstract

This study investigates the process of interaction between the non-uniform electromagnetic field of a primary transducer and a metallic cylindrical article in order to obtain multiparametric information. The study tackles the scientific and technical task of expanding the functional capabilities of an electromagnetic transducer by increasing the number of controllable parameters for an article at a single excitation frequency using the same transducer. The method is based on extracting the amplitude and phase of the spatial harmonics of the non-uniform probing field. The advantage of such transducers is in the fact that, while operating at a single fixed excitation frequency, they enable multiparametric inspection of metal articles. The results have practical significance for the instrumentation industry when designing and manufacturing primary transducers with a spatially periodic structure of the excitation magnetic field. This makes it possible to perform contactless monitoring of the electrical, magnetic, and geometric parameters of cylindrical articles of various sizes and types. For a transducer having two poles with currents in opposite directions, at γ = 36° and d/а = 0.5, the influence of the 5th spatial harmonic on the extracted 1st and 3rd harmonics is zero, while the influence of the 7th harmonic on the 1st and 3rd harmonics amounts to 0.36% and 2.7%, respectively. The influence of the 7th harmonic on the 3rd can be reduced to 1% by choosing d/a = 0.4. An algorithm for monitoring three parameters of a cylindrical article has been developed, based on the normalized amplitudes of the 1st and 3rd harmonics and the phase of the 1st harmonic, thereby expanding the functional capabilities of the method. It has been established that the influence of higher spatial harmonics on the measurement results is insignificant, and the total error does not exceed 1.5% without higher harmonics, in contrast to single-frequency methods where the error exceeds 5%.