Papers by Author: Bronius Karaliunas

Abstract: The purpose of the wok is to derive analytical expressions of spectral characteristics at electrical braking of linear induction motor with diverse number of poles as well as to provide results of calculations. The major task in the analysis of braking modes is to determine spectral characteristics of braking current, primary magnetic field and braking force. To this aim Maxwell equations were solved together with Fourier and Laplace integral transformations. The obtained results indicate that in addition to the main component of the magnetic field, when the space frequency is , in the process of braking there appears continuous spectrum of elementary components with the frequencies occupying the infinite sector from - to + . Due to that fact, during the process of energy conversion at the moment of braking, there participate positive – sequence, negative – sequence components and elementary components of the continuous spectrum, motionless in the space.

Abstract: The paper considers some problems of calculating spectral characteristics of magnetic field of the linear induction motor (LIM), operating at the electrical braking modes. In automatic drives with LIM the electric braking modes are usually applied: dynamic, recuperation, single – phase, capacitor type, braking by means of opposite connection, by pulsating current and inverter type (frequency) braking. During the process of braking in the moving part of the LIM and in some cases in an inductor there are initiated complicated interrelated electromagnetic and electromechanical non – stationary processes. The braking processes have been analysed in the motionless right – sided Descartes system of coordinates x, y, z. There have been presented the expressions of volumetric density of braking current which have been regarded the non – periodic functions of coordinate x. Besides that in cases of single – phase and capacitor braking these expressions are also regarded as the non – periodic functions of time. Therefore when compiling the mathematical model there have been applied Laplace and Fourier integral transformations. After having applied Fourier transformation there have been received the expressions of the spectra amplitudes of primary magnetic field at the dynamic braking under the condition that the number of excited zones in the inductor is even, uneven and fractional. The continuous spectra of amplitudes have been calculated by the software Mathcad 2001 Profesional.

Abstract: The paper considers some problems of calculating major parameters and characteristics of a mechatronic system with a linear induction motor (LIM). It has been shown that LIM operating in the presence of traveling magnetic fields are widely used alongside other actuators. These motors allow for modular design because inductors may be made as independent modules. Then, by choosing the required number of inductors and their arrangement in a mechatronic system, a desired trajectory of transverse motion may be obtained. A theoretical model for LIM calculation, taking into account major assumptions about onedimensional magnetic field, is offered. Complex amplitude is expressed as the exponential function of a longitudinal coordinate of current volumetric density of the inductor. The above inductances as the parameters of dynamic equations may be used in further investigation of dynamics of mechatronic systems. However, in order to create optimal control systems for mechatronic systems with linear actuators, the major parameters and characteristics of a linear motor should be known. Therefore, the present investigation is aimed at developing methods for calculating the parameters of mechatronic systems with linear electric drives.

Abstract: The main flaws of electric arc welds and factors determining the quality of the welded seams are considered in this paper. In practice, welding tools and their control systems are affected by some external factors causing deviation of the weld’s quality from the specified values. Currently used control systems of welding tools do not always satisfy the requirements for quality of welded joints. Major principles of developing the adaptive control system of the welding tool are considered here and the developed functional and block diagrams of microprocessor system are presented. General equations describing the welding process are also provided and the obtained transfer function of a closed system is described.