Approximate Equivalent Circuit Research Articles

Analytical solutions using special trans functions theory for current–voltage expressions of perovskite solar cells and their approximate equivalent circuits

Perovskite solar cells (PSC) have been recognized as devices with a constant increase in power conversion efficiency, confirming this promising technology’s upward trend. This paper deals with the mathematical modeling of current voltage and inverse voltage-current relationships of PSCs, in which standard equivalent circuits, as well as approximate equivalent circuits where series or parallel resistance is neglected, are investigated. Analytical solutions for voltage-current and current–voltage dependencies are derived for all investigated circuits. Furthermore, analytical solutions for short-circuit current and open-circuit voltage are derived. All nonlinear formulations of these dependencies are solved by applying special trans function theory. This paper proposes an enhanced algorithm called the Chaotic African Vultures Optimization Algorithm (Ch-AVOA) for PSC’s parameter estimation. The proposed algorithm is compared with other algorithms in terms of the convergence speed to the global solution and other statistical test measures to validate the algorithm’s efficiency.

Compact dual-band rectangular T E10 mode to circular TM01 mode converter for telemetry/telecommand applications in satellite communication: design, equivalent circuit modeling, mode level measurement technique and 3d printed manufacturing

In this study, the design of a dual-band mode converter, which provides transition from rectangular waveguide T E10 mode to circular waveguide TM01 mode and operates simultaneously in telemetry/telecommand (TT&C) frequencies, is presented along with its equivalent circuit and a mode level measurement technique. This dual-band converter is designed to uniformly excite TT&C slot antennas used in satellite communication with symmetric circular TM01 mode. The structure can work as a transceiver due to having one common rectangular waveguide feed. As a Ku-band application, a converter giving high purity TM01 mode at circular waveguide at 11.75 GHz/TX and 13.75 GHz/RX center frequencies is designed and manufactured with 3D printing technology. Approximate equivalent circuit models of the designed structure are extracted by using lumped elements from simulated S-parameter results. In addition, a measurement technique to detect the normalized power levels of different propagation modes in dual-band mode converter is applied on the manufactured structures to obtain transmission levels of circular TM01 mode and suppression levels of circular T E11 mode. It is revealed from the measurement results that while the designed structure gives more than 17.5 dB return loss and suppression of T E11 mode, and less than 0.6 dB insertion loss of TM01 mode within 500 MHz bandwidth at TX band, it gives more than 23 dB return loss and suppression of T E11 mode, and less than 0.3 dB insertion loss of T M01 mode within 900 MHz bandwidth at RX band.

Broadband Bandpass Filter for UWB Networks with Multiple In-Band Transmission Zeros

Proposed in this manuscript is a broadband bandpass filter (BPF) with dual in-band transmission zeros (TZs) and elongated stopband for application in ultra-wideband (UWB) networks. The basic structure is developed on the principle of broadside coupling of microstrip-to-coplanar waveguide (CPW). Semi-elliptical microstrips on the top are arranged in back-to-back manner and coupled to the open circuited CPW in the ground. The basic BPF is of 3rd order with good insertion/return loss. To this basic BPF structure multiple defected ground structures (DGS) in the shape of complimentary split ring resonator (CSRR) are appended to place dual Tzs within the passband and later dumbbell-shaped DGS are engraved in the CPW to widen the stopband. Also, an approximate equivalent lumped element circuit model is developed and its frequency characteristics matched against full-wave EM simulation. The proposed dual notched BPF is finally fabricated and is found to occupy a compact area of 13.6 × 6.75 mm2.

IDENTIFICATION ERROR OF UNBALANCE VOLTAGE SOURCES IN POWER SUPPLY SYSTEMS BY THE DISTORTING NODAL CURRENT CRITERION

One of the properties of electrical energy, that causes significant economic losses for both suppliers and consumers of electricity, is voltage unbalance. The most universal criterion for identifying voltage unbalance sources is the nodal distorting current. The accuracy of its determination depends on the method of measurement organization and is characterized by the greatest error for the local approach. The reason for this lies in an approximate method for determining the equivalent circuits of consumers of electrical energy and their parameters when measuring the parameters of the network operation mode only at one point of common connection to the power supply system. Analysis of the influence of approximate equivalent circuits and their parameters on the determination of the nodal distorting current showed that adequate identification of the sources of voltage unbalance distortion is possible only in the reverse sequence. At the same time, it is difficult to accurately determine the error in calculating this criterion in real time measurements due to the presence of additional unknowns that are required for its calculation. Based on this, it is proposed to carry out an upper estimate of this error. This required the introduction of additional functions with the search for their maximum under the given constraints. In addition, the uncertainty associated with the non-zero value of the identification criterion for a non-asymmetric consumer of electricity was taken into account that led to the need to introduce a dead zone for it. As a result of the studies carried out, expressions were obtained for an upper estimate of the error in determining the criterion for identifying sources of voltage symmetry distortion in the reverse sequence and determining its dead zone in real time measurements in relation to three-phase three- and four-wire power supply systems.

Design of an equivalent dielectric film using periodic patterned screen printing and prediction of dielectric constants based on equivalent circuit method

This study proposed a method to control the electromagnetic (EM) properties of a material by controlling its pattern dimensions. A conductive paste, comprising graphite and carbon black, was printed on the surface of a high-heat resistant polyester film with rectangular patterns using screen printing. The EM parameters of the material were extracted using one-dimensional approximate equivalent circuit method and the dielectric constant of the material was predicted. The pattern width had a positive correlation with the EM parameters, including the dielectric constant. The equivalent dielectric constant changed with the substrate thickness and surface resistance, as obtained from the parametric study. EM wave absorbers were designed based on transmission line theory and fabricated by stacking the developed materials with various dielectric slab materials. The results of the measurement and simulation confirmed the effectivity of the EM absorber design using the proposed material.

Approximate Equivalent Circuits to Understand Tradeoffs in Geometry of On-Chip Inductors

We develop an approximate frequency-independent equivalent circuit for integrated inductors on semiconducting substrates. All values of LCR in the equivalent circuit can be calculated directly from inductor geometry. The equivalent circuit captures: the skin effect, the proximity effect, the substrate capacitive loss, and the distributed capacitance. With careful definition of inductor quality factor, we are able to calculate the contribution of substrate capacitive loss and benefits of a substrate shield. Our model was put to test by successfully predicting the published quality factors of various inductors and proving that their geometries are close to optimum.

НАБЛИЖЕНА ЗАСТУПНА ЕЛЕКТРИЧНА СХЕМА СИНХРОННОГО ЯВНОПОЛЮСНОГО ГЕНЕРАТОРА ДЛЯ АНАЛІЗУ НАВАНТАЖУВАЛЬНИХ РЕЖИМІВ РОБОТИ АВТОНОМНИХ ВІТРО- ТА ГІДРОЕЛЕКТРИЧНИХ УСТАНОВОК

Синхронні явнополюсні генератори знаходять широке застосування в складі вітро- та гідроелектричних установок малої потужності. На сьогодні набуває актуальності задача застосування потужних автономних вітроелектричних установок з синхронними генераторами для накопичення частини генерованої ними енергії на гідроакумулювальних електростанціях. Розроблення раціональних схемо-технічних рішень реалізації даної технології для багатоагрегатних вітроелектростанцій потребує аналізу навантажувальних режимів роботи всіх складових в широкому діапазоні робочих швидкостей вітру і частоти обертання. Ефективне моделювання та проведення розрахункових досліджень перебігу електромеханічних процесів в даних системах може бути реалізовано шляхом застосування заступних електричних схем генераторів та двигунів, проте для явнополюсного синхронного генератора неможливо побудувати точну заступну електричну схему для електрорушійної сили обмотки якоря. В рамках цього дослідження розроблено наближену заступну електричну схему фази явнополюсного синхронного генератора та виконано оцінку можливих похибок результатів розрахунку параметрів навантажувального режиму схеми за різних значень частоти обертання ротора. Схема базується на послідовному ввімкненні активного опору обмотки якоря та індуктивних опорів розсіювання і поперекової реакції якоря, а також індуктивного опору, зумовленого сумісною дією поперекової та повздовжньої реакцій якоря. Очікувані похибки визначення розрахункових параметрів напруги споживачів автономної системи електроживлення на основі вітро- та гідроелектричних установок з синхронними явнополюсними генераторами за використання розробленої заступної електричної схеми не перевищують 2,5% по модулю та 1,5 електричних градусів по фазі для довільного значення частоти обертання ротора генератора в діапазоні 0,6...1,2 номінального значення. Застосування розробленої заступної електричної схеми явнополюсного синхронного генератора надає можливості проведення автоматизованих багатоваріантних розрахункових досліджень електромеханічних перехідних процесів в системах електроживлення на основі вітро- та гідроелектричних установок з урахуванням пульсацій швидкості вітру, зміни витрат та напорів води, зміни навантаження. Бібл. 24, табл. 3, рис. 3.

Quad Band Waveguide Bandpass Filter Using Slot Ring and Complementary Split Ring Resonators

In this paper, a combination of slot ring and complementary split ring resonators has been proposed to achieve quad band bandpass filter response in waveguide. The resonators have been formed on a Roger RO 4350 substrate with their common centre at the middle of the substrate. Two such structures have been placed on the transverse plane of a WR–90 waveguide at a distance of 8.41 mm to achieve the dual pole quad band response. Necessary simulations have been carried out using Ansoft HFSS (version 14). Measured result shows a quad band bandpass response with centre frequencies at 8.51/9.46/10.47/12.05 GHz and 3-dB bandwidth 0.256/0.2287/0.445/0.755 GHz, respectively. Approximate equivalent circuit of the filter is also proposed. The filter is 10 mm long.

Investigation of Shorting Vias for Suppressing the Open Stopband in an SIW Periodic Leaky-Wave Structure

Shorting vias loading in a substrate integrated waveguide (SIW) periodic leaky-wave structure is investigated for suppressing the open stopband. The SIW periodic leaky-wave structure with transverse slots can have the beam scanned in the backward and in the forward directions, but suffers from a large open stopband in which the reflection coefficient is increased and the gain drops drastically. A set of shorting vias are adopted to load the structure in each unit cell for suppressing the open stopband. The working principle of the technique is explained, with approximate equivalent circuits. When the slot and the shorting vias are spaced by a quarter guided wavelength, the series inductance in the slot can be canceled out by the shunt inductance in the shorting vias, and therefore, the open stopband can be suppressed. An antenna based on the via-loaded periodic structure is designed for validation. Simulation and measured results validate that the open stopband is successfully suppressed with the loading of shorting vias.

A compact broadside coupled dual notched band UWB-BPF with extended stopband

This manuscript describes a compact multi notched band ultrawide band (UWB) bandpass filter (BPF) based on broadside coupling of microstrip and co-planar waveguide (CPW). Initially, a meandered CPW embedded in ground plane is optimized efficiently to allocate the resonant modes equi-spaced within the UWB passband (3.1–10.6 GHz) and later, the tight coupling of the transition of microstrip with the CPW ensures a smooth passband. Four open ended stubs are appended with the microstrip patches on top to attenuate dual passband frequencies and improve higher stopband performance. An approximate equivalent circuit model of the prototype is developed and its circuit response is compared with full wave EM simulation data. The compact prototype measures only 13 × 7 mm2.

Compact Triple-Band Waveguide Bandpass Filter Using Concentric Multiple Complementary Split Ring Resonators

This paper presents a compact tri-band waveguide bandpass filter using concentric multiple complementary split ring resonators (CSRRs). Two symmetrical concentric multiple CSRRs are placed on the transverse plane of a standard WR-90 rectangular waveguide at 8.41[Formula: see text]mm distance to achieve dual-pole, tri-band response. The proposed filter has been simulated using Ansoft High Frequency Simulation Software (version 14). Based on the simulated result the filter has been fabricated and tested. The measured result shows a dual-pole, tri-band, bandpass response with passbands at 8.04–8.2675[Formula: see text]GHz, 9.45–9.84925[Formula: see text]GHz and 11.35–12.005[Formula: see text]GHz, which is in good agreement with the simulated responses. The total length of the filter is 10[Formula: see text]mm, which makes it compact and light weight. An approximate equivalent circuit of the filter also has been provided.

Planar ACS Fed Dual Band Antenna With DGS for Wireless Applications

A novel Asymmetric Coplanar Strip (ACS) fed antenna with Defected Ground Structure (DGS) suitable for dual application is presented. The Method of Moments (MoM) based mentor graphics IE3D electromagnetic solver has been used for this design. Dual band operation has been obtained by modifying the ground plane of the proposed design with spur-slots. It has been fabricated and tested with the overall size of 21x15x1.6 mm3 . The measured results indicate that the proposed antenna yields <-10dB impedance bandwidth of 13.13% and 9.86% which meets the requirement of 3.5GHz and 5.5GHz Wireless Local Area Network (WLAN) and World Wide Interoperability Microwave Access (WiMAX) applications. The approximate lumped equivalent circuit extraction for the proposed DGS fed dual band antenna has been discussed in detail. Because of its stable radiation patterns with low cross polarization,miniature size, high average antenna gain of 2.5dBi and good electromagnetic characteristics, the proposed antenna is a promising candidate for dual mode wireless communication devices.

Equivalent circuit model of a coaxial excited microstrip‐fed quasi‐lumped element resonator antenna array

An approximate lumped-parameter equivalent circuit model of the quasi-lumped element resonator antenna array is presented. The array consists of six series resonant circuits of frequency-independent elements, each with an interdigital finger capacitor (IDC), and shorted across by a parallel narrow strip inductor. Each resonator exhibits an aperture size of 0.207λg × 0.2λg at a centre frequency of 5.8 GHz, with entire array size of 2.857λg × 1.07λg . The resulting design is fed by a microstrip line and excited by a coaxial feed probe. A simple equivalent circuit model representing the six resonant circuits as well as the coaxial feed probe circuit, using the magnetic-frill model approach but with the simplest uniform-current model is described to predict the characteristics of the proposed resonator (and by extension, the proposed array), the effects of the coaxial probe and the microstrip feed line. Simulated data obtained from a full wave analysis using finite integration technique commercial solver is compared with the Agilent advanced design system results of the equivalent circuit. The derived equivalent circuit model was validated both analytically and by numerical simulations.

Planar UWB Filter with Multiple Notched Band and Stopband with Improved Rejection Level

AbstractAnalysis and realization of a microstrip-based planar ultra-wideband (UWB) filter with integrated multiple notch elimination property and simultaneously extended upper stopband is proposed. Initially, a UWB filter based on back-to-back microstrip-to-CPW technology is designed. Later, multiple spiral defected ground structures (DGS) are embedded to obtain multiple passband notches. Further, double equilateral U (DEU)-type DGS are used to improve upon the rejection level in upper stopband. The multiple passband notches are results of embedded spiral-shaped DGS (SDGS), while extended upper stopband is the outcome of suppressed higher-order spurious harmonics. The flexible dual-attenuation poles of DEU-shaped DGS suppress the stopband harmonics and widen the stopband. An approximate lumped equivalent circuit model of the proposed filter is modelled. The filter is compact and its layout measures 25.26 mm × 11.01 mm. The measured result is in good agreement with the full-wave electromagnetic (EM) simulation and circuit simulation.

Electrochemical impedance characterisation of tungsten trioxide–polyaniline nanocomposites for room temperature acetone sensing

Composites of WO3 nanoparticles and water-soluble polyaniline (PANI) particles doped with dodecyl benzenesulphonic acid at different mass ratios were deposited onto interdigitated electrodes and characterised using electrochemical impedance spectroscopy in air and in acetone vapour. The nanocomposites displayed an approximate equivalent circuit model of a parallel resistance and small inductance due to the PANI and a constant phase element (CPE) due to the WO3. The contribution of the CPE increased with increased WO3 loading. The nanocomposites mostly displayed increases in their real impedance on exposure to acetone at frequencies below 1kHz, as well as a small increase in imaginary impedance. However, low WO3 loadings and low acetone concentrations resulted in decreases in film resistance. This effect is due to the balance of charge carriers in the film. The resulting sensors were able to detect 10ppmv acetone at room temperature.

A Simple Equivalent Circuit for Small RFID Tag Antennas in Low Loss Dielectric Materials

Small radio frequency identification (RFID) tag antennas are generally designed to achieve conjugate matching with capacitive chips at the called tag resonant frequency. An approximate equivalent circuit is proposed to represent the antenna input impedance in low loss dielectric materials. It consists of a shunt conductance considered to be linearly proportional to loss tangent, an input resistance and reactance of antenna in lossless materials. Comparing with the simulated result of full wave numerical tool, the equivalent circuit gives acceptable errors in input resistance and reactance at the tag resonant frequency and nearby. The simple equivalent circuit can be used to reduce the repetitive simulation work for different loss tangent.

Approximate model and low‐order harmonic reduction for high‐voltage direct current tap based on series single‐phase modular multilevel converter

The series single-phase modular multilevel converter (SSP–MMC) is investigated as one option for high-voltage direct current tap aimed to reduce the number of switching devices by one-third. First an approximation method is applied to calculate the sub-module capacitor voltage of the proposed SSP–MMC. Based on that, the approximate equivalent circuits for ac and dc sides are both presented to demonstrate the mechanism of the second and third harmonics. Then the methods to reduce the second and third harmonics are proposed as parts of the overall control loop. Simulation results obtained in power system computer aided design (PSCAD) are provided to validate the brief equivalent models and the second and third harmonic reduction methods.

UWB-BPF WITH APPLICATION BASED TRIPLE NOTCHES AND SUPPRESSED STOPBAND

An ultra-wideband (UWB) bandpass fllter (BPF) with application oriented triple notches and simultaneously suppressed stopband is proposed. Implementing complementary split ring resonator (CSRR) and novel complementary meandered folded split ring resonators (CMFSRR) shaped defected ground structures (DGS) in the ground of proposed structure generates the triple notch in the UWB passband. The notch positions are functions of CSRR/CMFSRR proflle dimensions. Stopband is suppressed using the dual attenuation poles generated by the double equilateral-U (DEU) shaped DGS. An approximate lumped equivalent circuit model of the proposed fllter is presented. Measured results obtained are in good agreement with the equivalent circuit model and full wave electromagnetic (EM) simulation. The fllter is small in size with an overall area of 26:06mm£ 11mm.

Approximate Equivalent-Circuit Modeling and Analysis of Type-II Resonant Immittance Converters

Resonant immittance converter (RIC) topologies can transform a current source into a voltage source (Type-I RICs) and vice versa (Type-II RICs), thereby making them suitable for many power electronics applications. RICs are operated at a fixed frequency where the resonant immittance network (RIN) exhibits immittance conversion characteristics. It is observed that the low-frequency response of Type-II RINs is relatively flat and that the state variables associated with Type-II RINs affect the response only at the high frequencies in the vicinity of the switching frequency. The overall response of a Type-II RIC is thus dominated by the filter response, which is particularly important for the controller design. Therefore, an approximate equivalent circuit model and a small-signal model of Type-II RICs are proposed in this paper, neglecting the high-frequency response of Type-II RINs. While the proposed models greatly simplify and speed-up the analysis, it adequately predicts the open-loop transient and small-signal ac behavior of Type-II RICs. The validity of the proposed models is confirmed by comparisons of their results with those obtained from a cycle-by-cycle simulation and with an experimental prototype.

Nanocapacitor with a Cantor Multi-Layered Structure

We calculate numerically the quantum capacitance of a nanocapacitor formed of oxide-silicon layers deposited alternately with their widths following a Cantor set structure. We show that this configuration brings about a nano-hybrid capacitor which allows a classical and quantum behavior depending on the Cantor generation. In addition, we propose an approximate equivalent circuit representation for the nano-hybrid capacitor.