Володимир Мороз - Academia.edu (original) (raw)
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Papers by Володимир Мороз
Energies
Some electrical devices contain a solid nonlaminated magnetic core as a component. In the case of... more Some electrical devices contain a solid nonlaminated magnetic core as a component. In the case of variable magnetic flux, eddy currents arise in such a core, which should be taken into account for computer simulation if higher precision is needed. The fractional order transfer function (FOTF) based on the simple traditional model of excitation circuit of a DC machine is proposed for eddy current simulation. This model is illustrated by mathematical (based on differential equations and the Laplace operator) and structural approaches to the excitation circuit of a common DC generator with a solid core. The skin effect for more precise simulation of eddy currents is also considered by means of fractional order transfer functions in the computer models. Magnetic saturation and hysteresis were not taken into account in this case. The proposed model is simple and ensures adequate accuracy, confirmed experimentally using the FOTF Toolbox for MATLAB and Simulink. This model is distinct and ...
Журнал електроенергетичні та електромеханічні системи, 2021
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The investigation of the dynamic properties of solar batteries (SB) at the changes of loading res... more The investigation of the dynamic properties of solar batteries (SB) at the changes of loading resistance is described in this article. The results of research are illustrated by the oscillograms, which show the presence of inertia properties of SBs.
2021 22nd International Conference on Computational Problems of Electrical Engineering (CPEE), 2021
In the research article the role of numerical methods in the calculation of transients in electri... more In the research article the role of numerical methods in the calculation of transients in electrical circuits. Numerical methods are considered as digital filters that have behavioral features and have some influence. The pole/zero method is taken as a basis, which allows to obtain a graphical result and clearly demonstrates the conclusions obtained in the calculations.
Tekhnichna Elektrodynamika, 2021
The purpose of the research under consideration is to develop a mathematical model to calculate t... more The purpose of the research under consideration is to develop a mathematical model to calculate the trajectories of the ferromagnetic operating elements (millstones) of an electromagnetic mill, moving in a rotating magnetic field under electrodynamic and hydrodynamic resistance forces being limited by the space of the mill’s working chamber. The millstone motion is described through the equations of plane motion of arbitrary-shaped two-dimensional body. The driving forces of this motion are determined on the basis of the approximation of the tabulated functions connecting the module and the orientation of the equivalent force applied to the millstone, with its position in the working chamber and composite MMF phase of mill inductor winding. These tabulated functions are derived from the estimation of the magnetic field inside a working chamber with millstones, in two-dimensional quasi-stationary approximation, using FEM analysis. The publication contains the approximation algorithm ...
Журнал електроенергетичні та електромеханічні системи, 2020
According to the theory of automatic control, there should be no behavior's difference between an... more According to the theory of automatic control, there should be no behavior's difference between an object given by a set of transfer functions, which are respectively interconnected, and a real object, corresponding to such a theoretical structure with given transfer functions. Accordingly, a generalized analysis of the Otto Smith hypothesis regarding the stability indices in automatic control systems with unstable zeros and poles of second-order transfer functions is carried out. Due to the fact that the behavior of most technical objects can be described by a second-order transfer function, the main accent is placed on the second-order transfer function with a denominator with unstable zeros and poles. In the article, both the apparatus of transfer functions and the structural models of the appropriate level were used for the description, which made it possible to make their description evident. A generalized description of a second order automatic control system with negative feedback is made. For Influence analysis of unstable zeroes and poles on the stability of the Feedback Systems 53 such a system, theoretical stability criteria have been formed with respect to its parameters on the basis of necessary and sufficient conditions of stability. On the basis of the common description of the second-order transfer function, the study of automatic control systems with different variants of placement on the complex plane of unstable zeros and poles of the open system's transfer function was performed. The presentation of the material is accompanied by numerous examples, for which cases of transfer functions with both real poles and a pair of complex conjugated poles are considered. The case of both open system and feedback system is considered for each example given in the article. Both cases are illustrated in each example by bode plots and a step response. The researches carried out in the article are illustrated by bode plots and step responses, which for each example are obtained using mathematical applications MATLAB (with the library Control System Toolbox) and Mathcad. According to the results of our research, O. Smith's conclusions about the difference in the behavior of real physical systems with unstable zeros and poles and theoretically obtained models with similar transfer functions are confirmed.
Energy Engineering and Control Systems, 2015
Журнал електроенергетичні та електромеханічні системи, 2020
Modern digital control systems make it possible to implement quite complex control strategy, the ... more Modern digital control systems make it possible to implement quite complex control strategy, the complexity of which is limited by the hardware capabilities, the available software and the implemented control algorithm. An important component of such an algorithm is the numerical method, which allows to discretize the control rule on the basis of a continuous prototype. Such application example is the classic PID controller, which has become the basis for the development of digital control systems. Two mathematical operations are performed in such a controller: integration and differentiation, which in a digital system obtain discrete equivalents in the corresponding recurrent equations form. The article considers a digital PID controller as a digital filter, which with the use of the frequency characteristics (Bode diagrams) allowed to determine its most "narrow" place-the high-frequency diagram region that correspond to the differentiating part of the controller. This made it possible to focus the research on the practical implementation of the differential part of the digital PID controller. It is shown that the traditional way of the differential operation performing by the simple method of finite differences has some of disadvantages that make it fundamentally impracticable, as illustrated by the corresponding graphs. To eliminate the limitations of the traditional differential operation by the finite difference method, two variants of structural schemes of a real differentiator are proposed. The first variant of the real differentiator proposed to build on the structural scheme in feedback with the integrator. The second variant of the real differentiator is proposed to build according to the structural scheme with a parallel connection of the proportional and the first order blocks. The application of explicit numerical Adams integrators (also known as Adams-Bashforth rule) from the first to the fourth order under the conditions of physical realization is proposed to perform sampling. A study of both their frequency characteristics and their behavior performed on a noisy signal for these structural schemes. All research in the article was conducted using the Control System Toolbox library of the mathematical application MATLAB. It is shown that the use of the proposed real differentiation methods allows simple and efficient implementation of digital PID controllers.
Журнал електроенергетичні та електромеханічні системи
In this section we study state space models of continuous-time linear systems. The corresponding ... more In this section we study state space models of continuous-time linear systems. The corresponding results for discrete-time systems, obtained via duality with the continuous-time models, are given in Section 3.3. The state space model of a continuous-time dynamic system can be derived either from the system model given in the time domain by a differential equation or from its transfer function representation. Both cases will be considered in this section. Four state space forms-the phase variable form (controller form), the observer form, the modal form, and the Jordan form-which are often used in modern control theory and practice, are presented. 3.1.1 The State Space Model and Differential Equations Consider a general th-order model of a dynamic system represented by an th-order differential equation
Energies
Some electrical devices contain a solid nonlaminated magnetic core as a component. In the case of... more Some electrical devices contain a solid nonlaminated magnetic core as a component. In the case of variable magnetic flux, eddy currents arise in such a core, which should be taken into account for computer simulation if higher precision is needed. The fractional order transfer function (FOTF) based on the simple traditional model of excitation circuit of a DC machine is proposed for eddy current simulation. This model is illustrated by mathematical (based on differential equations and the Laplace operator) and structural approaches to the excitation circuit of a common DC generator with a solid core. The skin effect for more precise simulation of eddy currents is also considered by means of fractional order transfer functions in the computer models. Magnetic saturation and hysteresis were not taken into account in this case. The proposed model is simple and ensures adequate accuracy, confirmed experimentally using the FOTF Toolbox for MATLAB and Simulink. This model is distinct and ...
Журнал електроенергетичні та електромеханічні системи, 2021
,
The investigation of the dynamic properties of solar batteries (SB) at the changes of loading res... more The investigation of the dynamic properties of solar batteries (SB) at the changes of loading resistance is described in this article. The results of research are illustrated by the oscillograms, which show the presence of inertia properties of SBs.
2021 22nd International Conference on Computational Problems of Electrical Engineering (CPEE), 2021
In the research article the role of numerical methods in the calculation of transients in electri... more In the research article the role of numerical methods in the calculation of transients in electrical circuits. Numerical methods are considered as digital filters that have behavioral features and have some influence. The pole/zero method is taken as a basis, which allows to obtain a graphical result and clearly demonstrates the conclusions obtained in the calculations.
Tekhnichna Elektrodynamika, 2021
The purpose of the research under consideration is to develop a mathematical model to calculate t... more The purpose of the research under consideration is to develop a mathematical model to calculate the trajectories of the ferromagnetic operating elements (millstones) of an electromagnetic mill, moving in a rotating magnetic field under electrodynamic and hydrodynamic resistance forces being limited by the space of the mill’s working chamber. The millstone motion is described through the equations of plane motion of arbitrary-shaped two-dimensional body. The driving forces of this motion are determined on the basis of the approximation of the tabulated functions connecting the module and the orientation of the equivalent force applied to the millstone, with its position in the working chamber and composite MMF phase of mill inductor winding. These tabulated functions are derived from the estimation of the magnetic field inside a working chamber with millstones, in two-dimensional quasi-stationary approximation, using FEM analysis. The publication contains the approximation algorithm ...
Журнал електроенергетичні та електромеханічні системи, 2020
According to the theory of automatic control, there should be no behavior's difference between an... more According to the theory of automatic control, there should be no behavior's difference between an object given by a set of transfer functions, which are respectively interconnected, and a real object, corresponding to such a theoretical structure with given transfer functions. Accordingly, a generalized analysis of the Otto Smith hypothesis regarding the stability indices in automatic control systems with unstable zeros and poles of second-order transfer functions is carried out. Due to the fact that the behavior of most technical objects can be described by a second-order transfer function, the main accent is placed on the second-order transfer function with a denominator with unstable zeros and poles. In the article, both the apparatus of transfer functions and the structural models of the appropriate level were used for the description, which made it possible to make their description evident. A generalized description of a second order automatic control system with negative feedback is made. For Influence analysis of unstable zeroes and poles on the stability of the Feedback Systems 53 such a system, theoretical stability criteria have been formed with respect to its parameters on the basis of necessary and sufficient conditions of stability. On the basis of the common description of the second-order transfer function, the study of automatic control systems with different variants of placement on the complex plane of unstable zeros and poles of the open system's transfer function was performed. The presentation of the material is accompanied by numerous examples, for which cases of transfer functions with both real poles and a pair of complex conjugated poles are considered. The case of both open system and feedback system is considered for each example given in the article. Both cases are illustrated in each example by bode plots and a step response. The researches carried out in the article are illustrated by bode plots and step responses, which for each example are obtained using mathematical applications MATLAB (with the library Control System Toolbox) and Mathcad. According to the results of our research, O. Smith's conclusions about the difference in the behavior of real physical systems with unstable zeros and poles and theoretically obtained models with similar transfer functions are confirmed.
Energy Engineering and Control Systems, 2015
Журнал електроенергетичні та електромеханічні системи, 2020
Modern digital control systems make it possible to implement quite complex control strategy, the ... more Modern digital control systems make it possible to implement quite complex control strategy, the complexity of which is limited by the hardware capabilities, the available software and the implemented control algorithm. An important component of such an algorithm is the numerical method, which allows to discretize the control rule on the basis of a continuous prototype. Such application example is the classic PID controller, which has become the basis for the development of digital control systems. Two mathematical operations are performed in such a controller: integration and differentiation, which in a digital system obtain discrete equivalents in the corresponding recurrent equations form. The article considers a digital PID controller as a digital filter, which with the use of the frequency characteristics (Bode diagrams) allowed to determine its most "narrow" place-the high-frequency diagram region that correspond to the differentiating part of the controller. This made it possible to focus the research on the practical implementation of the differential part of the digital PID controller. It is shown that the traditional way of the differential operation performing by the simple method of finite differences has some of disadvantages that make it fundamentally impracticable, as illustrated by the corresponding graphs. To eliminate the limitations of the traditional differential operation by the finite difference method, two variants of structural schemes of a real differentiator are proposed. The first variant of the real differentiator proposed to build on the structural scheme in feedback with the integrator. The second variant of the real differentiator is proposed to build according to the structural scheme with a parallel connection of the proportional and the first order blocks. The application of explicit numerical Adams integrators (also known as Adams-Bashforth rule) from the first to the fourth order under the conditions of physical realization is proposed to perform sampling. A study of both their frequency characteristics and their behavior performed on a noisy signal for these structural schemes. All research in the article was conducted using the Control System Toolbox library of the mathematical application MATLAB. It is shown that the use of the proposed real differentiation methods allows simple and efficient implementation of digital PID controllers.
Журнал електроенергетичні та електромеханічні системи
In this section we study state space models of continuous-time linear systems. The corresponding ... more In this section we study state space models of continuous-time linear systems. The corresponding results for discrete-time systems, obtained via duality with the continuous-time models, are given in Section 3.3. The state space model of a continuous-time dynamic system can be derived either from the system model given in the time domain by a differential equation or from its transfer function representation. Both cases will be considered in this section. Four state space forms-the phase variable form (controller form), the observer form, the modal form, and the Jordan form-which are often used in modern control theory and practice, are presented. 3.1.1 The State Space Model and Differential Equations Consider a general th-order model of a dynamic system represented by an th-order differential equation