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A comparative study has been conducted on methods for accounting for the influence of losses in the stator iron of squirrel-cage induction motors on the operating parameters. A comparison was made between reference data and calculation results of the nominal mode parameters of an asynchronous motor without considering losses in the stator iron and with their consideration using equivalent resistances connected in parallel to the motor, as well as equivalent circuits of losses in the stator. The effect of the ratio of active and inductive components of the load of equivalent stator loss circuits on the results of mathematical modeling has been investigated. The study was carried out based on a universal mathematical model of an asynchronous motor of electromechanical systems with an arbitrary stator winding scheme. An algorithm for determining and adjusting the parameters of the stator loss circuits during the integration of the differential equations of electrical and mechanical balance of the asynchronous motor to a steady-state value has been developed, based on the values of losses in the stator iron (depending on the induction and frequency) and the effective value of the current of the equivalent circuit. To ensure solution stability, the use of an iteration coefficient and discretization of resistance adjustment has been justified. The application of stator iron loss circuits in the mathematical model of an asynchronous machine in generator mode has been justified, when the use of parallel connected equivalent resistances contradicts the machine's energy diagram. [ABSTRACT FROM AUTHOR]

Accurate calculation of equivalent circuit parameters is a prerequisite for accurately calculating the large‐capacity synchronous condenser parameter model. Due to its special transient operating conditions, the high transient magnetic saturation effect during operation causes the non‐linearity and time‐varying of the equivalent circuit parameters. The field mutual leakage reactance is the critical factor affecting the field current, and the time‐varying of the equivalent circuit parameters is closely related to the field current. However, the existing equivalent circuit parameter calculation methods considering field leakage reactance cannot achieve time‐varying parameters. A calculation method of time‐varying equivalent circuit parameters based on a back propagation neural network algorithm is proposed, which solves the calculation problem of time‐varying equivalent circuit parameters considering field mutual leakage reactance. Then, a 300MVar condenser is taken as the research object, and the proposed method is used to simulate the different operating conditions of the condenser and verified by the finite element method and experiment. The results show that the method improves the calculation accuracy of the equivalent circuit parameter model, reduces the calculation time, and applies to different operating conditions. [ABSTRACT FROM AUTHOR]

Abstract Accurate calculation of equivalent circuit parameters is a prerequisite for accurately calculating the large‐capacity synchronous condenser parameter model. Due to its special transient operating conditions, the high transient magnetic saturation effect during operation causes the non‐linearity and time‐varying of the equivalent circuit parameters. The field mutual leakage reactance is the critical factor affecting the field current, and the time‐varying of the equivalent circuit parameters is closely related to the field current. However, the existing equivalent circuit parameter calculation methods considering field leakage reactance cannot achieve time‐varying parameters. A calculation method of time‐varying equivalent circuit parameters based on a back propagation neural network algorithm is proposed, which solves the calculation problem of time‐varying equivalent circuit parameters considering field mutual leakage reactance. Then, a 300MVar condenser is taken as the research object, and the proposed method is used to simulate the different operating conditions of the condenser and verified by the finite element method and experiment. The results show that the method improves the calculation accuracy of the equivalent circuit parameter model, reduces the calculation time, and applies to different operating conditions.

Abstract Precisely interpreting frequency response analysis (FRA) curves is crucial when investigating mechanical malfunctions in power transformer windings (TWs). However, many conventional explanations of FRA features cannot be validated by an equivalent circuit (EC) that represents winding structures using resistance, inductance, and capacitance components in a ladder network. Incorrect interpretation can lead to misdiagnosis and confusion in asset management. Previous ECs are often proposed by analysing winding structures without rigorous verification compared to the corresponding FRA data. The specific EC is acquired using the transfer function (TF) derived from the measured FRA data. This allows for the establishment of the relationship between TW FRA curves, TF equations, and EC topologies. The precise interpretation of FRA curves can be achieved by closely observing the FRA curves created from TFs and ECs. The remarkable similarity between the measured and modelled FRA curves verifies the authenticity of the derived ECs. This significant achievement clarifies many misunderstandings regarding FRA and represents a substantial advancement in FRA technology.

Precisely interpreting frequency response analysis (FRA) curves is crucial when investigating mechanical malfunctions in power transformer windings (TWs). However, many conventional explanations of FRA features cannot be validated by an equivalent circuit (EC) that represents winding structures using resistance, inductance, and capacitance components in a ladder network. Incorrect interpretation can lead to misdiagnosis and confusion in asset management. Previous ECs are often proposed by analysing winding structures without rigorous verification compared to the corresponding FRA data. The specific EC is acquired using the transfer function (TF) derived from the measured FRA data. This allows for the establishment of the relationship between TW FRA curves, TF equations, and EC topologies. The precise interpretation of FRA curves can be achieved by closely observing the FRA curves created from TFs and ECs. The remarkable similarity between the measured and modelled FRA curves verifies the authenticity of the derived ECs. This significant achievement clarifies many misunderstandings regarding FRA and represents a substantial advancement in FRA technology. [ABSTRACT FROM AUTHOR]

Impedance Spectroscopy (IS) is a general term for the technique referring to small-signal measurements of the linear electrical response of a domain of interest. This method is based on the analysis of the system's electrical response to yield helpful information about its domain-dependent physicochemical properties (generally, the analysis is carried out in the frequency domain). Nowadays, there are many areas of application where IS can be used to evaluate or enhance the development of emerging products and processes. As a contribution to this field of research, this paper presents relevant theoretical–practical aspects of the interpretation and analysis of the electrical behavior of materials based on IS and IS modelling. The work starts by historically introducing IS and then goes through different domains of application of the technique, such as Materials Science and correlated areas. Afterwards, an introduction to IS usage for constructing equivalent electrical circuits is presented, aiming at modelling the materials' electrical behavior, followed by examples from the literature that use the two possible circuit development approaches, the series and the parallel association of circuit elements. Lastly, the authors present a case study of their most recent efforts of a circuit model development of relative humidity (RH) sensors based on heterogeneous mixed metal oxide (MMO) nanostructures, used to understand and identify existing contributions to the overall electrical response of the sensors to moisture; in their case, the electrical response of the MMO sensors was modelled with a high level of superposition between the experimental and fitted data, using a parallel combination of circuit elements, which is an unconventional one. [ABSTRACT FROM AUTHOR]

Electrical equivalent circuits are a widely applied tool with which electrical processes can be rationalized. There is a wide‐ranging selection of fields from bioelectrochemistry to batteries to fuel cells making use of this tool. Enabling meta‐analysis on the similarities and differences in the used circuits will help to identify commonly used circuits and aid in evaluating the underlying physics. We present a method and an implementation that enables the conversion of circuits included in scientific publications into a machine‐readable form for generating machine learning datasets or circuit simulations. [ABSTRACT FROM AUTHOR]

Electrochemical Impedance Spectroscopy (EIS) is a widely used, nondestructive electrochemical technique for analyzing many different systems. Currently, the most popular analysis method for EIS data is via Equivalent Circuit Models (ECMs). Many programs exist for constructing ECMs and fitting them to data, but these programs are often closed-source. In this work, we present an open-source program for equivalent circuit modeling called DECiM, which relies heavily on human input but is easy to operate. With two examples, we show how DECiM can easily and effectively validate spectra and construct and fit ECMs to data. The simple structure and open-source nature of DECiM make implementing new features easy, rendering the program versatile for impedance data analysis.

Abstract Harmonic magnetic gears (HMGs) have the advantage of lubrication‐free, high speed ratio and high torque density, which make it an attractive solution for safety critical applications. Due to eccentricity caused by machining and assembly, HMG suffers from dynamic eccentricity (DE) in operation, however, its effect on HMG performance is still unknown. Transmission characteristic of HMG under DE is studied. First, a magnetic equivalent circuit (MEC) model of HMG is proposed to build the magnetic coupling torque analytically, and the geometry of air gap is analysed parametrically to derive its equivalent reluctances. Flux density and coupling torque can be acquired by solving MEC equations. The accuracy of the MEC model is verified by finite element method. To study the transmission characteristic, an electromechanical coupling simulation framework for HMG is constructed, motion trajectories of rotors are investigated in case of DE, the output torque in locked‐rotor condition and speed response in continuous operation can be derived by simulation. It is found that torque ripples that have the same frequency with input rotor are induced by DE; the results are then verified in the experiment. This paper provides a theoretical guidance for the design and condition monitoring of HMG.

Abstract The two‐dimensional (2D) analytical model for the calculation of the components of the flux density distribution in the air gap in a dual‐stator axial‐field flux‐switching permanent magnet (PM) motor (DSAFFSPM) is presented. The novelties of this study are deriving a 2D hybrid analytical model and replacing the rotor teeth with some surface currents for the calculation of air‐gap magnetic flux density for the first time in the DSAFFSPM motor. The 2D analytical model for DSAFFSPMs is more challenging due to the doubly salient structure and inner PM of the stator. 1D analytical interior PMs are first transferred to the bore of the stator body using the magnetic equivalent circuit model (MEC). Next, the effects of the rotor teeth are taken into consideration by injecting virtual surface currents for 2D analytical model. Applying boundary conditions and solving the Laplace/Poisson equations, the vertical and tangential flux components of the flux density distribution in the air‐gap DSAFFSPM motor are computed. The verification of the proposed method and the obtained results are validated by the 3D finite element method.

Metamaterial components and antennas are based on the general understanding that an artificial structure composed of adequately designed and manufactured elementary cells or arrays has unusual resonance and propagation properties. Metamaterials exhibit equivalent values of the dielectric constant and magnetic permeability that are both negative simultaneously, in contrast with ordinary materials. Single elements, periodic, or quasi-periodic configurations can be suitable for a metamaterial response. In this paper, equivalent circuits for microwave propagation and resonance are compared, deriving a lumped element modeling complementary to those already available in the literature, with a particular focus on planar resonating devices and calculating the effective value for the dielectric constant and the magnetic permeability directly from experimental findings using the impedance (Z-parameters) notation. [ABSTRACT FROM AUTHOR]

This paper introduces a new approach for analyzing the dynamics of DC–DC converters. Currently, the primary widely accepted method for examining dynamic processes is the Small Signal Analysis technique. However, when applied to modern complex converters, this method poses additional challenges in formulating and solving systems of differential equations. The method proposed in this paper is based on its application to the analysis of dynamic modes of energy functions—Lagrangians. These functions make it possible to define simple criteria to describe the course of dynamic processes, and in the end define an equivalent (approximating) conventional converter identical to the original one with respect to the course of dynamics. If the magnetic and electrical energies in the Lagrangians of both the converters are equal, the outcome is practically identical transient processes. These findings were confirmed by both theoretical analysis and experimentally modelling the dynamics of the initial converter and an equivalent to it in the Matlab–Simscape program. An additional possibility of using the transfer functions of a conventional boost converter for the theoretical analysis of the converters of much greater orders is also discussed. The authors' experiments confirm the correctness of their theoretical conclusions. [ABSTRACT FROM AUTHOR]

The dynamics of photoexcited carriers in magnetron sputtered ZnO films is characterized employing time-domain impedance analysis, which is based on the measurements of the surface photovoltage (SPV) transients. The studies focus on observing the damage after the implantation of Nd+ ions in ZnO layers and a subsequent anneal. We observed the positive and negative components of the measured SPV transient and develop equivalent circuits of the structure involving multiple series of parallel resistance (R), capacitance (C), and inductance (L) elements, and derive a simple fitting procedure which allows to reproduce accurately the measured SPV transient. The relationship between these RCL elements and a rough physical picture of the charge transport phenomena in the interface regions of the structure is envisaged. This approach is conceptually useful for characterizing interfaces in semiconductor structures and devices. [ABSTRACT FROM AUTHOR]

Harmonic magnetic gears (HMGs) have the advantage of lubrication‐free, high speed ratio and high torque density, which make it an attractive solution for safety critical applications. Due to eccentricity caused by machining and assembly, HMG suffers from dynamic eccentricity (DE) in operation, however, its effect on HMG performance is still unknown. Transmission characteristic of HMG under DE is studied. First, a magnetic equivalent circuit (MEC) model of HMG is proposed to build the magnetic coupling torque analytically, and the geometry of air gap is analysed parametrically to derive its equivalent reluctances. Flux density and coupling torque can be acquired by solving MEC equations. The accuracy of the MEC model is verified by finite element method. To study the transmission characteristic, an electromechanical coupling simulation framework for HMG is constructed, motion trajectories of rotors are investigated in case of DE, the output torque in locked‐rotor condition and speed response in continuous operation can be derived by simulation. It is found that torque ripples that have the same frequency with input rotor are induced by DE; the results are then verified in the experiment. This paper provides a theoretical guidance for the design and condition monitoring of HMG. [ABSTRACT FROM AUTHOR]

The two‐dimensional (2D) analytical model for the calculation of the components of the flux density distribution in the air gap in a dual‐stator axial‐field flux‐switching permanent magnet (PM) motor (DSAFFSPM) is presented. The novelties of this study are deriving a 2D hybrid analytical model and replacing the rotor teeth with some surface currents for the calculation of air‐gap magnetic flux density for the first time in the DSAFFSPM motor. The 2D analytical model for DSAFFSPMs is more challenging due to the doubly salient structure and inner PM of the stator. 1D analytical interior PMs are first transferred to the bore of the stator body using the magnetic equivalent circuit model (MEC). Next, the effects of the rotor teeth are taken into consideration by injecting virtual surface currents for 2D analytical model. Applying boundary conditions and solving the Laplace/Poisson equations, the vertical and tangential flux components of the flux density distribution in the air‐gap DSAFFSPM motor are computed. The verification of the proposed method and the obtained results are validated by the 3D finite element method. [ABSTRACT FROM AUTHOR]

Unbalanced-fed Tightly-Coupled Dipole Arrays (TCDAs) allow for the realization of ultrawideband, wide-scanning phased arrays without the need for baluns, which may increase size, weight, and cost. However, unbalanced-fed TCDAs often have additional radiating modes and common-mode resonances which may degrade performance. In this paper, a scan impedance model is presented which describes performance in terms of a combination of even and odd monopole and dipole radiating modes. An intermodal coupling term is included to account for performance when scanning in the E-plane. Each mode is calculated individually in a full-wave solver and the model is then validated by comparing the proposed combination to a full simulation of the unbalanced-fed TCDA. A coaxial extension technique is then introduced to increase the impedance of the monopole-like radiating even mode, allowing the unbalanced-fed array to match the performance of the balanced-fed version without shorting posts or significant redesign of the elements or lattice.

An extraction method to obtain the noise model parameter $T_{\mathrm { d}}$ in deep submicron MOSFETs directly from radio frequency (RF) scattering parameters and noise figure measurements is presented. A simplified noise equivalent circuit, along with closed-form solutions to calculate the RF noise figure of MOSFET is developed. On-wafer experimental verification is presented and a comparison with tuner based method is given. Good agreement is obtained between simulated and measured results for $16\times 1\times 2{{\mu }\rm m}$ (number of gate fingers $\times $ unit gatewidth $\times $ cells) gatelength MOSFETs.

The t-rail electrode is an effective method to enhance the silicon optoelectronic modulator's performance. To design and optimize T-rail electrodes, engineers often rely on finite-element numerical simulations that require complex device modeling and enormous computing resources. In this paper, we present an equivalent circuit model for carrier-depletion-based push-pull silicon modulators with T-rail electrodes. The analytical solution for the bandwidth of the modulator can be derived from the equivalent circuit. The utilization of the analytical solution offers advantages in terms of memory conservation and flexibility. The values calculated by the equivalent circuit model are in excellent agreement with the numerical full-wave HFSS simulations. Hence, the proposed model can accurately and efficiently develop silicon optical modulators.

Abstract This paper introduces a new approach for analyzing the dynamics of DC–DC converters. Currently, the primary widely accepted method for examining dynamic processes is the Small Signal Analysis technique. However, when applied to modern complex converters, this method poses additional challenges in formulating and solving systems of differential equations. The method proposed in this paper is based on its application to the analysis of dynamic modes of energy functions—Lagrangians. These functions make it possible to define simple criteria to describe the course of dynamic processes, and in the end define an equivalent (approximating) conventional converter identical to the original one with respect to the course of dynamics. If the magnetic and electrical energies in the Lagrangians of both the converters are equal, the outcome is practically identical transient processes. These findings were confirmed by both theoretical analysis and experimentally modelling the dynamics of the initial converter and an equivalent to it in the Matlab–Simscape program. An additional possibility of using the transfer functions of a conventional boost converter for the theoretical analysis of the converters of much greater orders is also discussed. The authors’ experiments confirm the correctness of their theoretical conclusions.

Impedance Spectroscopy (IS) is a general term for the technique referring to small-signal measurements of the linear electrical response of a domain of interest. This method is based on the analysis of the system’s electrical response to yield helpful information about its domain-dependent physicochemical properties (generally, the analysis is carried out in the frequency domain). Nowadays, there are many areas of application where IS can be used to evaluate or enhance the development of emerging products and processes. As a contribution to this field of research, this paper presents relevant theoretical–practical aspects of the interpretation and analysis of the electrical behavior of materials based on IS and IS modelling. The work starts by historically introducing IS and then goes through different domains of application of the technique, such as Materials Science and correlated areas. Afterwards, an introduction to IS usage for constructing equivalent electrical circuits is presented, aiming at modelling the materials’ electrical behavior, followed by examples from the literature that use the two possible circuit development approaches, the series and the parallel association of circuit elements. Lastly, the authors present a case study of their most recent efforts of a circuit model development of relative humidity (RH) sensors based on heterogeneous mixed metal oxide (MMO) nanostructures, used to understand and identify existing contributions to the overall electrical response of the sensors to moisture; in their case, the electrical response of the MMO sensors was modelled with a high level of superposition between the experimental and fitted data, using a parallel combination of circuit elements, which is an unconventional one.

Metamaterial components and antennas are based on the general understanding that an artificial structure composed of adequately designed and manufactured elementary cells or arrays has unusual resonance and propagation properties. Metamaterials exhibit equivalent values of the dielectric constant and magnetic permeability that are both negative simultaneously, in contrast with ordinary materials. Single elements, periodic, or quasi-periodic configurations can be suitable for a metamaterial response. In this paper, equivalent circuits for microwave propagation and resonance are compared, deriving a lumped element modeling complementary to those already available in the literature, with a particular focus on planar resonating devices and calculating the effective value for the dielectric constant and the magnetic permeability directly from experimental findings using the impedance (Z-parameters) notation.

(a) Synthesis of Zr-BDC-MOF by solvothermal method, and (b) Electrochemical sensing of prepared Zr-BDC/GCE. [Display omitted] • Zr-BDC-MOF made by solvothermal method, resulting specific surface area (868 m2g−1) • Employed EIS to study non-electroactive OPPs' interaction with Zr-BDC-MOF/GCE. • LODs for malathion 3.6 nM, dimethoate 4.1 nM, chlorpyrifos 4.5 nM, monocrotophos 3.8 nM, and glyphosate 4.3 nM. • EIS showed Zr-BDC-MOF/GCE favors sulfur OPPs ((P = S), (P-S)) over P = O and other pesticides. Residues of pesticides found in fruits and vegetables pose a grave risk to organisms, potentially causing acute and chronic diseases when their levels surpass the maximum residual limits (MRLs) for human consumption. This study targeted to detect non-electroactive organophosphate pesticides (OPPs), including malathion, dimethoate, chlorpyrifos, monocrotophos, and glyphosate using a zirconium-terephthalic acid combined metal organic framework (Zr-BDC) by electrochemical impedance spectroscopy (EIS). Comprehensive analysis of the synthesized Zr-BDC showed an extensive specific surface area of 868 m2g−1. Nyquist plots and equivalent circuit models confirmed the higher adsorption of OPPs with P = S and P-S (malathion, dimethoate, chlorpyrifos) onto glassy carbon modified by Zr-BDC (Zr-BDC/GCE), in contrast to OPPs with P = O (monocrotophos, glyphosate, and non-OPPs). The Zr-BDC/GCE displayed a linear detection range of 5.0 nM to 70.0 μM, with limit of detections (LODs) of 3.6, 4.1, 4.5, 3.8, and 4.3 nM for malathion, dimethoate, chlorpyrifos, monocrotophos, and glyphosate respectively. The sensor exhibited notable recovery 91.0 – 98.6 % and RSDs 1.19 – 1.97 % (n = 3) when tested with real samples (apple and cabbage) and demonstrating substantial reproducibility and long-term stability. [ABSTRACT FROM AUTHOR]

Single-nanopore membranes constitute physical models for biological ion channels and are also central to electrochemical energy transducers, logical circuits in sensors and actuators, and converters in bioelectrical interfaces. The membrane potential, defined as the electrical potential difference established between two different ionic solutions separated by the membrane, is crucial for the electrical coupling of nanofluidic concentration cells to electronic components such as load capacitors and resistors. Here we analyze, theoretically and experimentally, the validity of basic principles governing electric circuit theory such as the Thévenin equivalent circuit, the additivity of voltages and resistances, and the Millman theorem in nanopore-based concentration cells. To this end, we consider a wide range of practical conditions with respect to salt concentrations, nanopore asymmetry, electrical capacitances, and series and parallel arrangements. Additionally, we investigate the scaling of the single pore results to the multipore case. The results obtained suggest that basic circuit models offer approximate tools to guide the analysis of the nanofluidic concentration cells. [Display omitted] [ABSTRACT FROM AUTHOR]