Bronisław Tomczuk

A hybrid field-circuit model of a single-phase shell-type transformer that incorporates a three-dimensional analysis of the magnetic field in a transformer with beveled edges of the magnetic shunt. The finite element method (FEM) was employed, and the expressions for computing the magnetic field's differential and integral parameters were provided. For various positions of the magnetic shunt, the self- and mutual inductances of the transformer windings are calculated. Their values are stored in matrix form and serve as input data for the transformer circuit model. The differential equations governing the operation of a transformer with a movable magnetic shunt are formulated using Lagrangian methods. They were applied to the transformer's T-type equivalent circuit. This simulation model has been verified experimentally. Comparison of the measured and simulated time-course currents yields a good agreement. Furthermore, three electric arc models have been introduced to assess the applicability of the proposed approach under nonlinear loading. The results confirm that the mathematical model accurately predicts the transformer transients across a range of operating scenarios. Moreover, the presented simulation offers potential for broader application to other electromagnetic objects.

To find the total core losses in 1-phase medium-frequency transformers, a 3D numerical field analysis was carried out. The proposed numerical modeling was based on the extended iterative homogenization method (IHM) developed by the authors. The achieved calculation results were validated by the corresponding values obtained experimentally, and a reasonably close agreement was obtained.

The article describes the process of selecting the design parameters of the electromagnetic actuator, which was used to regulate the compression pressure in the cylinder of an internal combustion engine. The electromagnetic actuator was installed in the timing system of a single-cylinder internal combustion engine, which forced its basic design parameters in terms of force and frequency of operation. For the electromagnetic actuator in question, field calculations of the esign variants of the linear electromagnetic actuator for two types of materials were conducted. The finite element method was applied to the computer-aided design of electromagnetic actuators. The influence of the magnetic circuit and the dimensions of the windings on the distribution of the magnetic field were analyzed. The thickness and height of the magnetic field induces, and the dimensions of the stator poles have been changed while maintaining the same external dimensions of the actuator for design reasons. All this work was aimed at improving the performance of the internal combustion engine in terms of improving efficiency in terms of partial engine loads. In this area, the internal combustion engine is characterized by low efficiency, significantly deviating from the maximum, and at the same time, during normal operation of vehicles is the area most often exploited.

This paper presents the design of and transient time simulations for a four-pole magnetic bearing with permanent magnets. The usage of permanent magnets reduces the consumption of electric energy in comparison to a traditional active magnetic bearing. Permanent magnets are installed in the yoke of the stator core to limit the cross-coupling of the magnetic flux generated by the windings. The first part of this paper presents the design of the magnetic bearing and its finite-element model, while the second part describes the field-circuit indirectly coupled finite-element model for the transient time simulation. The presented simulation model was used to calculate the transient response for the rotor lifting from the starting position, the step change in the rotor position and the change in the rotor position under an external impact force applied along the y-axis.

Dynamic characteristics for three types of railgun constructions were simulated and measured in this work. The simplest construction is the iron-less (IL) railgun, while the two other ones (IC and ICPM) have an iron-core. The iron-core permanent magnet (ICPM) railgun additionally has permanent magnets. To compare their characteristics, similar dimensions of the rails and iron cores were adopted, and the same power supply system was used. Numerical magnetic field analyses and our analytical models have been used to determine the electromagnetic parameters. They were verified experimentally. The transient states of the railguns were studied with our field-circuit mathematical model, and their results were also verified by experiments.

A three-dimensional analysis of the leakage magnetic field in a transformer with beveled edges in a magnetic shunt is described. This paper contains a mathematical description of the finite element method used in performing numerical calculations. Formulas allowing to determine the differential and integral parameters of the magnetic field were presented. Magnetic flux density distributions and the points with high values were determined in the shell-type core and movable shunt sub-areas. For different positions of the magnetic shunt, the short-circuit transformer reactance was calculated as the integral parameter of the above-mentioned magnetic field analysis. Their amounts for the extreme positions of the shunt were given, as well. The movable magnetic shunt geometry impact on the short-circuit current value is given. In order to validate the calculation results, the research included some point measurements of magnetic flux density vectors and the winding reactances as well, and good compliance with the simulation data has been obtained. Thus, this analysis can also be applied to other objects with movable shunts in their magnetic systems.

This paper presents an empirical study of a spark-ignition internal combustion engine with modifications made to increase its effectiveness. The modification was implemented bi-directionally in terms of changes to the compression ratio and changes to the engine’s valve train. The compression ratio was increased by 2.3 units by design and a hybrid intake valve opening control was used in the engine’s valve train. The hybrid control involved autonomous control of one of the inlet valves with a dedicated electromagnetic actuator. The designed electromagnetic actuator was mounted downstream of the single-cylinder engine’s intake system’s modified camshaft to control the effective compression pressure build-up. Field calculations were carried out for the electromagnetic actuator’s design variants and its current characteristics were determined. The multivariate calculations were carried out in order to find the quasi-optimal geometry of the actuator. The width and height of magnetic field coils and the dimensions of the stator poles were changed, while maintaining the same external dimensions of the actuator to enable its mounting in the cylinder head system. In the next step, the prototype of the actuator was made and placed on the combustion engine in order to conduct the experimental investigations. The work was aimed at improving the internal combustion engine’s efficiency at the low load range, as this is load range in which it has low efficiency despite it being the most often used during normal vehicle operation. The original measurement stand was prepared, and many tests were carried out in order to investigate the influence of the electromagnetic valve on the combustion engine characteristic. This improved the internal combustion engine’s efficiency at its low-load range by up to 25%. Both calculation and measurement results are presented in form of graphs.

A comparison of two developed simulation models for a hybrid magnetic bearing (HMB) transient states is presented. This applies to analyses using the flux-circuit directly coupled magnetic equivalent circuit and field-circuit indirectly coupled finite element analysis. The required control system was implemented for both models. The results obtained from the simulations were compared with those obtained from measurement tests.

Multivariate calculations of the electrodynamic accelerator with a permanent magnet support and a ferromagnetic core are presented in the paper. The calculations were made with using the Magnetostatic module of Maxwell/ANSYS software. The purpose of these calculations was to determine the size...

This paper concerns mathematical modelling of dynamic performances to a new permanent magnet electromagnetic valve actuator (PMEVA). Both static and transient characteristics were simulated by using the finite element method (FEM) and field-circuit approach. The magnetic force values versus the excitation current and the position of the valve actuator movable part have been determined. Our concept of the mover positioning relative to the radial magnets is quite novel. PMEVA parameters are satisfied for implementation in combustion engines. Transients in the device have also been analyzed for no-load and for the nominal burden of the actuator. The indications of the position sensors and the excitation current waves were simulated and measured for the step voltage supply. The calculation results were verified experimentally, and a good conformity has been observed. The advantages of our actuator are simple construction, short time of the switching, the current supplying being needed only at the runner extreme positions, and simple controlling. Additionally, PMEVA design can be extended to support the simultaneous operation of four valves.