Comparison of impulse processes in spatially shifted ring-like cores made of ferrite and thin sheet steel

Abstract

Purpose. Development of a numerical simulation model of pulse processes of magnetic cores made of ferrite and thin-sheet electrical steel in order to estimate the magnitude of pulse overvoltages. Methodology. The distribution of the electromagnetic field and eddy currents was calculated using the finite element method. Computer-aided design tools were used to develop geometric models of the computational domain of the studied processes in ring-shaped cores. The theory of transient processes and the laws of electric circuits were used to excite pulse processes in the studied system. Findings. A three-dimensional numerical ring-field mathematical model of pulse excitation of ring-shaped cores made of different materials of electrical steel of the sensor and inductor was developed, which is used to diagnose interturn short circuits of the filled windings. The model allows determining the time dependences of current, voltage and the nature of the change in magnetic flux during the passage of the pulse excitation front. The distributions of the electromagnetic field, eddy currents and the dynamics of their attenuation were obtained for different values ​​of the magnetic permeability and electrical conductivity of the materials. The obtained results allow us to quantitatively assess the influence of material parameters on pulse processes, to determine the limits of efficiency of using ferrite and cores from different types of electrical steel in high-frequency diagnostic systems, sensors and energy converters. Originality. The results of the analysis of numerical simulation modeling of the studied system showed that, depending on the type of core material, wave penetration processes with minimal losses are inherent in ferrite material. In thin-sheet steel, eddy currents in each individual sheet have a significant effect on pulse shielding, which significantly affects the output signal. Practical value. The obtained results can be used to build systems for diagnosing interturn insulation of windings of electrical machines, in particular, as a methodological basis for diagnostic devices based on the use of the proposed approach.