Parameters Of Circuit Elements Research Articles

Smartphone Fast Charger Analysis Based on RLC Circuit Transient Process

In today's era, the widespread adoption of mobile terminals, particularly smartphones, has been facilitated by the rapid advancements in information and communication technology. However, a notable drawback of smartphones is their high-power consumption, necessitating faster charging solutions to enhance user convenience. This paper focuses on the RLC circuit of fast chargers. Initially, it introduces the fundamental principles and associated protocols of fast charging technology, elucidating the operation of integrated circuits within fast chargers and highlighting the advantages of fast charging compared to conventional slow charging methods. Moreover, the paper conducts an in-depth analysis of the transient processes within the pivotal series RLC circuit in fast chargers, encompassing zero-input responses and sinusoidal AC excitation responses. The transient processes are categorized into overdamped, critically damped, or underdamped states based on circuit element parameters, with initial conditions and power supply phase determining whether the circuit transitions directly into a steady-state process when stimulated by sinusoidal AC. This research contributes to a deeper understanding of the RLC circuit within smartphone fast chargers and serves as a valuable reference for advancing the development of fast charging solutions.

An effective numerical method for analyzing the joint influence of the parameters of electric circuit elements on its operating modes

An effective numerical method for analyzing the joint influence of the parameters of electric circuit elements on its operating modes

Understanding Characteristic Electrochemical Impedance Spectra of Redox Flow Batteries with Multiphysics Modelling

Electrochemical impedance spectroscopy (EIS) is a non-destructive technique for analyzing electrochemical systems (such as redox flow batteries – RFBs). Battery researchers widely adopt equivalent circuit models (ECMs) to analyze EIS spectra of RFBs and attempt to use the circuit to deduce prevalent transport and kinetic properties [1]. Straightforward adoption of these ECMs suffers from some setbacks which need rectifying. There is a major issue of poor or inconsistent physical interpretation of the different circuit elements. ECMs of batteries are commonly used in real-time applications due to their simplicity and importance for determining properties like state-of-charge. However, prediction performance in low state-of-charge areas has to be improved [2], which reinforces the need to relate recorded spectra to the physical properties of cell components.Using an experimentally validated full Multiphysics model of single-cell vanadium RFB analyzed in the frequency domain, we approach understanding the EIS spectra characteristics based on the influence of cell features and operating parameters. To achieve our analyses, we investigate the effects of different cell properties and operating parameters on the Multiphysics model produced EIS spectra and the resulting ECM circuit element parameters that fit the spectra. Five different values for each cell property or operating parameter are considered for the following components: Electrode: Electrical conductivity, porosity vis a vie specific surface area and hydraulic permeability, reaction rate constants for the positive and negative sides.Membrane: Ionic conductivity, fixed charge concentration, porosity, and hydraulic permeability.Electrolyte: State-of-charge, Composition vis a vie bulk diffusion coefficients of species, density, and viscosity.

The power harmonic components distribution study in the power circuit of a dynamic voltage restorer

Purpose. Investigation of the distribution of harmonic power components in the power circuit of a dynamic voltage restorer. Methodology. On the basis of the differential equations of the power circuit of a dynamic restorer, a search for the relationship between the mode parameters and the parameters of the circuit elements is performed. On the basis of the obtained expressions, a model of a dynamic voltage regulator was created using the methods of mathematical modeling in the visual programming environment.. Findings. The equations that reflect the relationship between the mode parameters of a dynamic voltage restorer and the parameters of circuit elements are obtained. As a result of modeling the mode with different harmonic composition of current and voltage, the following features of the distribution of instantaneous power components are revealed. Originality. It has been established that the presence of different current and voltage harmonics acting in the transformer of a dynamic restorer causes additional power harmonics that are transformed in the windings. It is noted that the low-frequency power harmonics of the LC filter dominate on the capacitor, which is connected in parallel to the transformer winding, while the level of high-frequency components caused by PWM modulation for the capacitor and the filter choke differ slightly. The zero-frequency power component of the storage capacitor corresponds to a tripled zero-time power component at the output of the converter, which is due to its operation in three phases. This cannot be extended to the second and third harmonics of the powers of the converter and the capacitor; these components are absent in the latter, which is due to energy exchange processes between the phases of the converter. Practical value. Using the obtained expressions, the principle of determining the parameters of the elements of the power circuit of a dynamic voltage restorer, in particular, the storage elements, is formulated.

The Analysis, Modeling, and Control of the Forward DC/DC Converter for the Electric Vehicle

This article deals with the analysis, modeling, and control of the DC/DC converters. Although it is considered with the analysis of the power semiconductor converters in general however it can be applied also to sophisticated electronic devices perfectly suitable for on-board applications of a huge variety of transport vehicles. Specifically, as an example, the Forward type topology is used which offers the advantage of the galvanic isolation of output. The task is to obtain a state space description of the system, the transfer function of the control, and design controller parameters using MATLAB. The state space model and the transfer function is implemented for the ideal and nonideal type of topology, where it is considered with at least some parasitic parameters of circuit elements to get closer to real results of the physical sample and to compare obtained transfer functions based on their frequency characteristics.

Physical Interpretation of Mixed Ionic‐electronic Conductive Polymer‐coated Electrodes by a Simple Universal Impedance Model

AbstractA simple equivalent electrical circuit is used to obtain the physical parameters of electrical circuit elements from measured electrochemical impedance spectra. This model consists of four circuit elements with a clear physical meaning for each of the elements. Compared to complex models with multiple constant phase elements or Warburg impedances, our model is suitable for extracting physical values for important electrode parameters with low errors. The feasibility of the model was shown by investigating pure metal or polymer‐coated electrodes. Here, gold electrodes were coated either with Poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT : PSS), Polypyrrole:poly(styrenesulfonate) (PPy : PSS), or (PEDOT/PPy) : PSS by means of electropolymerization. The model could demonstrate the ionic‐electronic differences such as the ion accessibility of the differently coated electrodes. To prove the correctness of the model, the obtained results were compared to the literature.

Equivalent Circuit Model Analysis of Electromagnetic Metasurface Loaded With Plasma

An equivalent circuit model (ECM) is proposed for a Jerusalem cross metasurface structure loaded with plasma. Based on the microwave network theory, the electromagnetic properties of the composite structure are analyzed through this ECM. Due to the wave-absorbing effect of plasma, the parallel conductive and inductive elements are introduced to the ECM of the Jerusalem cross metasurface, forming the ECM of the composite structure. The circuit element parameters are extracted by genetic algorithm optimization. The consistency between the simulated reflection coefficient and the calculated ones by this model proves the accuracy of the proposed ECM for analyzing the electromagnetic properties of a composite structure. Moreover, the plasma collision frequency and the plasma electron density are selected within a certain frequency range to further prove the accuracy of this model. The influence of plasma parameters on the equivalent circuit element values is also analyzed. The ECM can predict the electromagnetic properties of the composite structure and provide theoretical guidance for the design.

Low-Frequency Oscillation Analysis in Train-Traction Power Supply System Using an SISO Voltage Loop Model

Low-frequency oscillation (LFO) in the train-grid coupling system severely endangers the stability and safety of railway operation. It is well known that this phenomenon is caused by impedance mismatch among the trains and the traction power supply system (TPSS). A novel voltage loop model of the single-phase pulsewidth modulation rectifier is proposed in this article. Unlike the commonly adopted multi-input multi-output (MIMO) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$d$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$q$ </tex-math></inline-formula> impedance model in the literature, this is a single-input single-output (SISO) model that enjoys some advantages, such as easier calculation of the system poles and quantitative analysis of the stability margin. The most attractive character of this model in comparison to the MIMO one is perhaps the decoupling of the controller and the voltage loop. This paves the way toward the analytical design of the dc-link voltage controller (DVC), whereas the impedance model is mainly useful for analysis. Furthermore, the maximum amount of trains allowed for keeping stability is derived from the steady-state equation. Robust stability margin (RSM) and sensitivity analysis are adopted to quantitatively investigate the influence of the control parameters and the circuit element parameters. LFO is guaranteed to be eliminated permanently by adjusting the controller parameters.

Improving a parameter determination method for multielement bi-poles used in digital dielcometric hygrometer of agricultural products

The article examines the possibility of determining the parameters of multi-element bi-pole using the author’s method of aggregate measurements. Mathematical modeling of measuring circuits is performed, the random error of the results of measurements of parameters of a four-element bi-pole by the Monte Carlo method is estimated and determination result of the methodological and random components of the measurement errors of parameters of circuit elements is presented. The relevance of the application of the combined method of research with measurements in steady-state and transient modes for determining the moisture content of agricultural products is justified. The reduction of the resulting methodological error and the possibility of reducing the number of analog-to-digital transformations without deteriorating the target accuracy are proved.

Long‐Term Stability of Reference Measuring System for Impulse High Voltage

Long‐term stabilities of shielded resistive voltage dividers for lightning and switching impulse, employed as the reference dividers of Japan High‐voltage Impulse testing Laboratory Liaison (JHILL) are investigated. The DC scale factors and the step‐response parameters have been annually measured for 20 years. Annual variations of impulse parameters, namely the peak value, the front time, and the time to half value of the calculated waveform from the step‐response waveforms by the convolution algorithm are investigated. Furthermore, long‐term stabilities of reference low‐voltage impulse calibrators are investigated. The parameters of circuit elements of the calibrators have been annually measured for 18 years. The impulse parameters of the output waveforms of the calibrators are calculated, and the annual variations of them are investigated. After the detailed evaluation, it can be expected that the measurement system employing the voltage dividers and the calibrators, including the analytical method of the data, has the similar performance to those of NMIs of developed countries. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Convergence of Levenberg-Marquardt Estimates of Nonlinear Parameters in EIS Analysis of Coated Aluminum Panels

Equivalent circuit models are frequently employed to analyze electrochemical impedance spectroscopy (EIS) data. However, aside from some simple cases in which the equivalent circuit element parameters can be estimated directly from a plot of the data, the parameters for each of the equivalent circuit elements must often be estimated through the implementation of a nonlinear least-squares regression method. One frequently-used approach is the powerful Levenberg-Marquardt algorithm. This algorithm functions as a damped least-squares method that performs an interpolation between the steepest-descent and the Gauss-Newton methods for estimating nonlinear parameters. However, there are several challenges to using a Levenberg-Marquardt algorithm to model EIS data. The nonlinear nature of the impedance equations along with the difference in the magnitude of the parameter values can result in the algorithm failing to converge to a local minimum in the parameter space. This convergence challenge can be seen in determining equivalent circuit values for undamaged coating systems that have a high pore resistance, a small capacitance, as well as contributions from the underlying metal substrate. A Levenberg-Marquardt algorithm, along with a heuristic approach to use the raw data to improve the initial parameter estimates, is implemented that provides an improved approach for nonlinear regression fits of equivalent circuit models. A comparison of three equivalent circuit models fits, with residuals, for a two-layer coating system on an aluminum substrate is shown in the attached figure.Figure caption: Plot of EIS data (+ symbols) from a cured coating system prior to any environmental exposures compared with 3 equivalent circuit model fits (solid lines). The model fits were obtained using an NRL-developed Levenberg-Marquardt nonlinear regression fitting routine.The Department of Defense Strategic Environmental Research and Development Program (SERDP) sponsored this project under work unit 5399. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Office of Naval Research, the U.S. Navy, the Department of Defense, or the U.S. government. Figure 1

Analysis of the DRT as Evaluation Tool for EIS Data Analysis

The Distribution of Relaxation Times (DRT) is an important analysis tool that is capable of giving initial information from Electrochemical Impedance Spectra (EIS) with respect to the number of relaxation processes occurring in the system and their corresponding relaxation frequencies. From this the possible number of circuit elements for the equivalent circuit model in the nonlinear least square fit of the data can be selected. There are several techniques and possibilities to perform the transformation [1–3], nevertheless every possibility has its limitation and/or will remain an ill-posed problem [4]. For our EIS data, the DRT transformation with the Tikhonov regularization is used for further analysis. Hence, we want to understand and more precisely describe the effects of this transformation together with occurring pitfalls on the most commonly implemented circuit elements used to describe EIS data for characterizing Solid Oxide Fuel or Electrolysis Cells (SOFC/SOEC) operating at high temperatures. Therefore, a database with the future possibility of pattern recognition is created for DRT transformations on selected circuit elements like a resistor in series with a finite length diffusion or Warburg-short element (R-Ws) or a resistor in parallel with a constant phase element (RQ). A parameter interval is selected for each occurring element. The origin for these data comes from a series of experiments where quite well fitting Equivalent Circuit Models (ECM) were analyzed with respect to their minimum and maximum values per element. Depending on the coverage of the interval, useful intermediate numbers are selected in order to perform parameter sweeps for every possible combination together with a downstream DRT transformation step. We obtain the behavior of the DRT transformation as a function of the individual circuit element parameters and can evaluate which occurring peaks belong to a circuit element and which ones are artefacts or numerical issues in the transformation. Additionally, the regularization parameter (λ) is taken as a sweep parameter as well to see its influence on the transformation. From both perspectives, we can state a range of optimal numbers of recorded data points per decade of frequency for experiments. We also can give a direction for selecting λ depending on what exactly is to be evaluated with the respective DRT transformation. Additionally, we are able to categorize peak-forming behavior of the transformation since the selected ECMs are known and so, in theory, its transformation result. Knowledge for the DRT behavior is also useful for modeling the electrolysis process where theoretical characteristics (i-V, EIS data) are calculated in order to validate and evaluate the model. Figure caption: Figure 1: The DRT transformation of the model RQ-RQ is converted into the frequency domain with a variation of αP1 from 0.5 to 1.0. The fixed parameters are q1 = 10-1 S, r1 = 0.303 Ω, q2 = 10-2 S, r2 = 0.303 Ω, αP2 = 0.8, λ = 10-7.

Rectangular current pulse generator to test varistors with pulsed electrical load

A brand-new circuit of a rectangular pulse current generator is presented. As a rule, generators consisting of 6-10 LC cells connected in series are used to obtain rectangular current pulses. Such units are very cumbersome and complicated in the selection of element parameters and adjustment, so a new scheme of pulse current generator was proposed. The main difference from the classical circuit is the method of generating a rectangular current pulse, i.e. by adding the currents from two parallel circuits connected to the load. The first circuit at discharge generates an aperiodic current pulse, the second generates an oscillatory current pulse. The total current pulse flowing through varistor has constant amplitude for some time. In a specified period of time, while the current pulse has a constant amplitude, there is an interruption of current with the help of a switching device. The given circuit solution is possible to implement when using fundamentally new switching devices of the IGBT module. A connection diagram of a pulse current generator for testing varistors with a classification voltage to 1200 V with adjustable pulse duration of 50, 1000, 2000 µs is proposed. The parameters of the generator circuit elements are determined. The measures aimed at suppression of overvoltages arising at break of current in circuits with high inductance as well as the tests confirming the operability of the designed circuit are carried out.

The outlook for multivibrator application in the present day electronic systems

The paper discusses challenges that the present-day electronic industry of the Russian Federation faces today, analyses reasons for lagging in this sector in volume and production scale of the finished products in comparison to the leading in this area countries, suggests ways for reaching a new level in this industry by implementing a nationwide digitalization, reviews a place of digital signals in modern-day electronic, their types, creation methods, main characteristics, devices for generation and processing. The method of digital signals forming using the multivibrator was suggested in this paper. Different multivibrator types were reviewed, including the multivibrator with AND-NOT gates, its advantages were considered in comparison with the transistor stage multivibrators, parameters of the electronic circuit elements in the AND-NOT gate multivibrator for generating a signal with the required characteristics were calculated, then the multivibrator was assembled and the output signal parameters were taken down. The output signal parameters and the calculated parameters were identical. The conclusion was made about the possibility of the suggested AND-NOT gate multivibrator application in the complex automatic control circuits and electronic systems indication circuits as a device that generates signals with the required parameters.

Quasi resonant converter for autonomous power supply

Quasiresonant converters (QRCs) are increasingly being used in autonomous power supply systems. These converters are efficient, have small dimensions, and operate stably when the load changes. This study is devoted to the development of a zero-current switching QRC with improved characteristics. The main advantages of this QRC are a wide range of regulation and a low level of output voltage ripple. These advantages are achieved by the recuperation of excess energy due to a transistor shunting the primary winding of a transformer. In this work, a mathematical model of advanced QRC (AQRC) is developed, and the quantitative relationship between the parameters of the AQRC power circuit elements is established. In addition, the electromagnetic processes occurring in the AQRC are studied on the Simulink model. Moreover, the AQRC characteristics for various operating modes are studied, and the rational parameters of its components are determined. Then, an AQRC prototype is created. The tests of the prototype are in good agreement with the models. Results show that the AQRC allows for the adjustment of the output voltage ranging from 0 to 100% of the rated value and has a standard level of electromagnetic compatibility.

Influence of Microcracks on Silver/Polydimethylsiloxane-Based Flexible Microstrip Transmission Lines

Microcrack is commonly seen as a defect in materials that affects the performance of flexible radio frequency (RF) devices. Here, we investigate the influence of microcracks on the RF characteristics of flexible microstrip by stretching flexible microstrip that is based on polydimethylsiloxane (PDMS) substrate and an Ag microparticles/PDMS (AgMP/PDMS) composite conductor. The RF characteristics of the microstrip were monitored with a variety of tensile displacements. An equivalent circuit model of the microstrip with microcracks was proposed to reveal the mechanisms. The fitting results matched the actual measurement well. In addition, the morphology of the microcracks was characterized by SEM and the direct-current (DC) resistance was monitored. The results show that the changes in equivalent circuit element parameters (R, L, C) are due to the change in the conductive pathways, which affect the transmission and reflection of the RF signals.

Specific aspects of calculating electrical energy losses in electricity networks

The paper present modes of operation of 10(6) kV distribution networks, which are determined by the loads of consumers. The network scheme is based on an open circuit, which allows you to perform calculations for each 10(6) kV distribution line (feeder) separately. The calculation of power losses in the electric network is carried out by the method of average loads. The paper determines the integral characteristics of the operational parameters of the head branch, determines the parameters of the equivalent power loss of the feeder equivalent circuit, and the equivalent circuit determines the energy loss in the feeder. The paper compiles the equivalent circuit of the considered network section, calculated the parameters of the equivalent circuit elements and determines the total power loss in all linear sections. The paper presents an algorithm for calculating the steady state using the example of a feeder and shows the sequence of calculation of current distribution in the branches of the equivalent circuit.

On the adequacy of the frequency-symbolic method for linear parametric circuits analysis

A frequency-symbolic method (FS-method) of the analysis of steady-state mode of linear parametric circuits is intended for forming their transfer functions in the frequency domain. Transfer functions are approximated by Fourier polynomials and contain a complex variable, time variable and parameters of circuit elements in the form of symbols. The coefficients of such Fourier polynomials by the FS-method are unknown in the symbolic systems of linear algebraic equations (SSLAE), and are defined as their solutions in symbolic form. In the paper we present a method of forming an approximation expression which ensures the adequacy of calculations. Examples and results of computer experiments are given. The system of functions MAOPCs based on a frequency-symbolic method is used for the optimal design of electronic devices of noise-immune hidden radio engineering systems using code signals.

Non-Catalytic Benefits of Ni(II) Binding to an Si(111)-PNP Construct for Photoelectrochemical Hydrogen Evolution Reaction: Metal Ion Induced Flat Band Potential Modulation.

We report here the remarkable and non-catalytic beneficial effects of a Ni(II) ion binding to a Si|PNP type surface as a result of significant thermodynamic band bending induced by ligand attachment and Ni(II) binding. We unambiguously deconvolute the thermodynamic flat band potentials (VFB) from the kinetic onset potentials (Von) by synthesizing a specialized bis-PNP macrochelate that enables one-step Ni(II) binding to a p-Si(111) substrate. XPS analysis and rigorous control experiments confirm covalent attachment of the designed ligand and its resulting Ni(II) complex. Illuminated J-V measurements under catalytic conditions show that the Si|BisPNP-Ni substrate exhibits the most positive onset potential for the hydrogen evolution reaction (HER) (-0.55 V vs Fc/Fc+) compared to other substrates herein. Thermodynamic flat band potential measurements in the dark reveal that Si|BisPNP-Ni also exhibits the most positive VFB value (-0.02 V vs Fc/Fc+) by a wide margin. Electrochemical impedance spectroscopy data generated under illuminated, catalytic conditions demonstrate a surprising lack of correlation evident between Von and equivalent circuit element parameters commonly associated with HER. Overall, the resulting paradigm comprises a system wherein the extent of band bending induced by metal ion binding is the primary driver of photoelectrochemical (PEC)-HER benefits, while the kinetic (catalytic) effects of the PNP-Ni(II) are minimal. This suggests that dipole and band-edge engineering must be a primary design consideration (not secondary to catalyst) in semiconductor|catalyst hybrids for PEC-HER.

IMPROVING THE EFFICIENCY OF ELECTROSTATIC PRECIPITATORS

This paper provides information on the achievements in development of gas cleaning. A critical analysis of functioning principle of electrostatic precipitators, which are currently being developed and operated, is conducted. The possibility of increasing the effectiveness of gas cleaning using unipolar voltage pulses has been analyzed. It has been found that a streamer mechanism of discharge or streamer shape of corona discharge is the case, when voltage pulses with over-voltage are used and electrostatic precipitators run. The most rational circuit for unipolar voltage pulses generation using low-voltage generators of periodic voltage pulses is identified. To separate space charges formed in the streamers' channel, it is proposed to use pulsating voltage with a direct component and a potential plane with corona needles-grounded plane electrode system. The analysis of transient process within feed circuit of discharge technological gaps has shown that cut-off pulse repetition frequency, in which stability of discharge current is ensured, depends on the parameters of feed circuit elements and the discharge gap capacitance. It was found that the use of corona discharge streamer form allows increasing the speed of the gas to be purified up to 8 m/s, and reducing the aerosol particles deposition zone to 1 m. The gas velocity is 1 m/s with a deposition zone of more than 27 m in an existing gas filling device (GFD) type electrostatic precipitator. When comparing these indicators, the energy intensity of the process decreases by more than 100 times, and the specific power of the gas flow purification process is 33 (W·s)/m3.