Researching Dynamic Processes in Electromechanical Braking Devices with Massive Magnetic System

The authors review the key specifics of electromagnetic wave penetration in a solid ferromagnetic core of the brake-release solenoid when its coil is powered by the DC current. The obtained experimental time-dependencies for the magnetic inductance in various parts of the core in the transient mode showed that eddy current excitation can be represented as a result of the crossing of core layers with a magnetic field moving at a certain speed from the internal border towards the center line. The field movement in the core is characterized by a significant unevenness of magnetic inductance with respect to coordinate
${r}$
. The analysis of experimental data helped obtain simplified formulae allowing to calculate the eddy current value induced in the core during transient operation modes. The formulae are based on a number of common assumptions. The authors demonstrate that when coefficient
${\sigma}$
depending on the core material is inserted in the calculation formulae, we can achieve a satisfactory alignment of the mean inductance curve with the experimental dependence
${B_{m}\left(t\right)}$
. The authors also describe the practical calculation of
${\sigma}$
using the experimental data. The obtained analytical dependencies help calculate the coil data for the brake-release solenoid and the brake response parameters taking into account the demagnetizing action of the eddy current by summing its value with the magnetomotive force of the coil determined while calculating the magnetic circuit.