МОДЕЛЮВАННЯ ОПТОЕЛЕКТРОННОГО НАВАНТАЖЕННЯ, ЯКЕ ЖИВИТЬСЯ ВІД ФОТОЕЛЕМЕНТА ТА АКУМУЛЯТОРА

Converting the frequency response of a network into an equivalent time-domain circuit is a common task in several fields, such as power system simulations. A few good methods, such as the vector fitting method, have been proposed to do the conversion. Unfortunately, these methods sometimes produce non-passive equivalent circuits which are hard to realize in time domain or can lead to unstable simulations. In order to address the concern, this paper proposes a new conversion method for single-input single-output systems with guaranteed passivity for the resulting circuit. The basic idea of the proposed method is to represent the equivalent circuit as a matrix with varying dimension and unknown values. Genetic algorithm is then applied to find the values and dimension by minimizing the errors between the desired frequency response and that produced by the equivalent circuit. Since the equivalent circuit consists of only passive elements, the circuit passivity is always guaranteed. Details of the problem formulation and the solution algorithms are presented in this paper. Performance of the proposed method has been confirmed by several case studies.

SUMMARY Active control of non-stationary response of a single degree of freedom vehicle model with nonlinear passive suspension elements is considered in this paper. The method of equivalent linearization is used to derive the equivalent linear model and the optimal control laws are obtained by using stochastic optimal control theory based on full state information. Velocity squared quadratic damping and hysteresis type of stiffness nonlinearities are considered. The effect of the nonlinearities on the active system performance is studied. The performance of active suspensions with nonlinear passive elements is found to be superior to the corresponding passive suspension systems.

In this paper the genetic algorithm is used to optimization of parameters the equivalent electrical circuit of piezoelectric ceramic. Sandwich type piezoelectric ceramic transducer are the source of power ultrasounds when the vibration is activated by a voltage inverter. The output frequency of inverter most by equals the mechanical resonance frequency of the transducer and most by tuning with very high precise. In real circuits the mechanical resonant frequency is function of many parameters of piezoelectric material. The equivalent electrical circuit of transducer transforms this parameters in electrical value. This electrical circuit consist of connection in parallel: Co end RLC elements and this units are part of the oscillating circuit of inverter. The values of equivalent electrical circuit varies during the operation of transducer in function extending parameters, among others, the most important are temperature and time. In this situation to obtain the optimal value of the output voltage frequency of inverter most by know electrical parameters equivalent circuit of transducer. In the resolution of difficult problems to by effective the genetic algorithm.

The influence of the PANI structure on the conductive mechanism and on the electrical equivalent circuit analysis

Solution of PDEs-electrically coupled systems with electrical analogy

The study of electromechanical systems based on Induction motors remains relevant, since this is the most popular type of converters. The article provides a systematic analysis of the entire range of converters, provides a rationale for the use of vector control systems in order to obtain the most energy efficient systems. The system of assumptions under which the dynamics of an Electromechanical system can be described using the mathematical apparatus of a standard oscillatory element is analyzed. For him, the most optimal way to correct the transient process of this element has been empirically identified. It has been successfully applied to the "ideal current source - Induction motor" system.

The given research is aimed at the mathematical modeling and synthesis of the electrical equivalent circuit of an electrochemical device as an element of an electrical circuit. Mathematical modeling is completed in the result of a systematic study of the concentration and electric fields in a two-electrode electrochemical system. The object of study is considered to be linear with constant parameters. The object sizes are considered to be insignificant that’s why the electric current density on the electrodes surface is assumed to be equally distributed. Diffusion in the electrolyte becomes the limiting stage of electrode processes in the system with a finite mass transfer rate. The Laplace operator method is used as a research method, it is used to calculate the voltage at the electrodes of an electrochemical device. The mathematical model of an electrochemical device has been developed in the run of the system study and an electrical equivalent circuit has been synthesized, which contains infinite number of parallel branches including active and reactive elements. Besides, analytical formulas have been obtained that can be used in the process of calculation individual discrete parameters on these branches. In case of engineering calculations, the number of branches in the electrical equivalent circuit can be limited with the finite number, specified by accuracy of the calculations. It should be also mentioned that as a result of the study, it has become possible to synthesize all kinds of particular characteristics of an electrochemical device as well as the opportunity to study the dynamics of various transition processes in it.

In this paper, a novel equivalent circuit of DC motors, which encompasses both electrical and mechanical parts, is presented. This equivalent circuit, which is more compact than the previously reported and requires only passive elements, allows for simulations of circuits containing DC motors to be carried out using SPICE program. Simulation and experimental results are shown to be in good agreement with theoretical calculation. The concept of this new equivalent circuit contributes to the understanding of DC motor operation using basic electrical circuit analysis.

In the present study two-phase BiNbO4//PVDF composites with 0-3 connectivity were studied by impedance spectroscopy within the frequency range Δν=100Hz-1MHz at room temperature. Polyvinylidene fluoride (PVDF) acted as a matrix whereas bismuth niobate (BiNbO4) powder acted as a dispersed phase. The volume fraction of the ceramic phase was cV=2, 4, 6, 8, 10, 16 and 20vol%. Analysis of the impedance data registered for composites as well as for BiNbO4 ceramics and PVDF polymer was performed on the base of complex dielectric permittivity mathematical formalism. It was found by impedance spectroscopy that concentration of the dispersed phase had an effect on dielectric properties of ceramic-polymer composite. Experimental data of impedance spectroscopy were fitted to the corresponding equivalent circuit using the complex non-linear least squares method. An equivalent electric circuit consisting of a series combination of two parallel combinations of a resistance R and a constant phase element CPE was found to describe well the dynamic dielectric response of the objects under study. Parameters of the equivalent electric circuit were calculated and it was found that two distinct relaxation processes were present in the composite samples. It was also found that volume fraction of the dispersed phase cV=8vol% corresponded to a local minimum of resistance whereas cV=10vol% of the dispersed phase corresponded to a local minimum of capacitance.

The ac impedance of (Bi1.5Zn0.5)(Nb0.5Ti1.5)O7, a relaxor ceramic with the pyrochlore structure, has been measured over the temperature range 10–1073 K and analyzed using a combination of traditional, fixed-frequency sweeps of permittivity and tan δ, impedance analysis using resistance-capacitance (RC) circuit combinations and equivalent circuit modeling with the inclusion of a constant phase element (CPE). Low temperature data accurately fit an equivalent circuit containing a parallel R-C-CPE element in series with a capacitor. From the temperature-dependence of the fitted R,C,CPE parameters, a model for the relaxor behavior is obtained.

Electrochemical impedance spectroscopy (EIS) is an important electrochemical technique that is used to detect changes and ongoing processes in a given material. The main challenge of EIS is interpreting the collected measurements, which can be performed in several ways. This article focuses on the electrical equivalent circuit (EEC) approach and uses grammatical evolution to automatically construct an EEC that produces an AC response that corresponds to one obtained by the measured electrochemical process(es). For fitting purposes, synthetic measurements and data from measurements in a realistic environment were used. In order to be able to faithfully fit realistic data from measurements, a new circuit element (ZARC) had to be implemented and integrated into the SPICE simulator, which was used for evaluating EECs. Not only is the presented approach able to automatically (i.e., with almost no user input) produce a more than satisfactory EEC for each of the datasets, but it also can also generate completely new EEC configurations. These new configurations may help researchers to find some new, previously overlooked ongoing electrochemical processes.

Optimal Design of electrical machines using population-based optimization algorithms needs computationally fast model for evaluating the performance characteristics from design data, i.e. geometric dimensions, winding layouts, material properties. The Electric Equivalent Circuit (EEC) is a simple and appropriate model with acceptable accuracy to be incorporated in the design procedure. In this paper, an analytical approach is presented for calculating the EEC parameters of large non-salient pole synchronous generator based on winding-function method. Although the synchronous generator is well recognized, calculation of its dynamic EEC parameters is not reported in previous studies. Special issues of high-rated industrial synchronous generators are considered such as rotor slots with different dimensions, rotor sub-slots, the damper winding which is created from rotor wedges and retaining rings, saturation of magnetic flux routes in d-q-axis and stator core stacking. The connections of damper windings in d-q-axis and definitions of turn-ratios to refer the parameters to the stator-winding side are of novelties of the research. The calculated parameters for a 200MVA power-plant generator are compared with the experimentally obtained parameters. The results of EEC analysis of the studied machine have acceptable coincidence with the experimental and 2D finite-element simulation results, which proves the validity of the proposed method.

This work presents the equivalent electrical circuit (EEC) analysis of the 2-way Doherty Power Amplifier (DPA). For this purpose, the sub-amplifiers used in the 2-way DPA are modeled using real voltage sources instead of ideal sources. For the first time, the general voltage and current equations for each node of the EEC are determined using circuit theory with transmission line concepts. The analysis results explain some of the empirical practices carried out in other works to tune the 2-way DPA response, such as offset lines or asymmetrical bias voltages, etc. This analysis allows us to examine the impact that the auxiliary sub-amplifier bias voltage has on the efficiency of the 2-way DPA, suggesting the use of the phase-to-amplitude distortion (AM-PM) of the auxiliary sub-amplifier to eliminate the compensation lines that are commonly implemented arbitrarily in the 2-way DPA, whose objective is to synchronize the output signals of the subamplifiers. The experimental data of a 20 W (43 dBm) 2-way DPA designed and fabricated for a central frequency of 1.875 GHz with GaN transistors validate the proposed idea, resulting in a compact design and a significantly reduced design time.

CHAPTER 6 - CAPACITANCE

Purpose. Modification of the numerical calculation method of transients in linear electric circuits, as well as the development of a schematic model of the method, leading to ease the calculation and to increase the speed of calculation on a computer..Methodology. Polynomials approximation of functions, numeral methods of solution of integro-differential equations, matrix methods, computer programming and methods of electric circuits theory are used.Findings The improved method of transient calculation is worked out as the modification of the known one. It allows to reduce the computer modeling time of dynamic electric processes in linear electric circuits. The example of the application of the proposed method is shown. Based on the developed method, the computer program was compiled for calculating the transient in the model circuit. This example showed the reduction in CPU time of 45% compared with the use of known methodsOriginality. The approximation of the functions of currents with time by series in the Chebyshev orthogonal polynomials is used. Chebyshev polynomials possess the property of the approximation error uniformity of functions in the entire range of the argument, which distinguishes them from a number of other orthogonal functions. It is proposed to use a polynomial approximation not of the solution functions themselves, but of its derivative. This significantly reduces the approximation error of both the solution function and the derivative of the solution, which appears in the calculation method.. It is shown how, in the proposed method, integro-differential equations of state are transformed into linear algebraic equations. The schematic model of the proposed numerical calculation method is developed. The schematic model allows you to move from an electrical circuit in which processes are described by integro-differential equations to an equivalent circuit with images of currents. Images of true currents in the equivalent circuit are interpreted as direct currents. It is shown that the Kirchhoff laws are valid for current images in the equivalent circuit, which leads to the calculation of a system of algebraic equations. Such a circuit model creates convenience for an engineer performing transient calculations.Practical value. The developed method opens up the possibility of using the entire diverse apparatus of the theory of electric circuits for working with current images. Based on this, a universal software package is developed for calculating transients in electrical circuits of arbitrary