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Showing papers on "Equivalent circuit published in 2012"


Journal ArticleDOI
TL;DR: In this paper, a comparative study of twelve equivalent circuit models for Li-ion batteries is presented, which are selected from state-of-the-art lumped models reported in the literature.

1,463 citations


Journal ArticleDOI
01 Mar 2012-Energy
TL;DR: In this article, the authors present a method to estimate the state-of-charge (SOC) of a lithium-ion battery, based on an online identification of its open-circuit voltage (OCV), according to the battery's intrinsic relationship between the SOC and the OCV for application in electric vehicles.

396 citations


Journal ArticleDOI
TL;DR: In this paper, a battery model with enough precision and suitable complexity is presented, where the model equations are built and the model parameters are identified with an online parameter identification method, and an evaluation is performed on the seven battery models by an experiment approach from the aspects of the estimation accuracy of the terminal voltages.

369 citations


Proceedings ArticleDOI
04 Mar 2012
TL;DR: In this article, a multi-temperature LiNi-CoMnO 2 cathode and graphite-based anode was used to simulate thermal buildup for a constant current discharge scenario, and the model was validated for a lithium cell with an independent drive cycle showing voltage accuracy within 2%.
Abstract: The growing need for accurate simulation of advanced lithium cells for powertrain electrification demands fast and accurate modeling schemes. Additionally, battery models must account for thermal effects because of the paramount importance of temperature in kinetic and transport phenomena of electrochemical systems. This paper presents an effective method for developing a multi-temperature lithium cell simulation model with thermal dependence. An equivalent circuit model with one voltage source, one series resistor, and a single RC block was able to account for the discharge dynamics observed in the experiment. A parameter estimation numerical scheme using pulse current discharge tests on high power lithium (LiNi-CoMnO 2 cathode and graphite-based anode) cells under different operating conditions revealed dependences of the equivalent circuit elements on state of charge, average current, and temperature. The process is useful for creating a high fidelity model capable of predicting electrical current/voltage performance and estimating run-time state of charge. The model was validated for a lithium cell with an independent drive cycle showing voltage accuracy within 2%. The model was also used to simulate thermal buildup for a constant current discharge scenario.

360 citations


Journal ArticleDOI
TL;DR: In this paper, a modified current-voltage relationship for the single-diode model is presented, based on the well-known equivalent circuit for a single photovoltaic (PV) cell.

319 citations


Journal ArticleDOI
TL;DR: In this article, the transmission and reflection properties of frequency-selective surfaces (FSSs) are evaluated through a simple and accurate first-order circuit approach, based on the parallel between real structure and a lumped-LC-network counterpart.
Abstract: The transmission and reflection properties of frequency-selective surfaces (FSSs) are evaluated through a simple and accurate first-order circuit approach The approximate analysis, based on the parallel between real structure and a lumped-LC-network counterpart, is also useful for acquiring physical insights into the working principles of frequency-selective surfaces The first part of the paper describes a technique for computing lumped parameters of the most common frequency-selective-surface elements The L and C parameters representing a given frequency-selective-surface element are derived only one time, at normal incidence, and stored, so as to form a database The second part of the paper deals with the derivation of simple relations allowing the generalization of the stored LC couples in the case where the frequency-selective surface is printed or embedded in arbitrarily thick dielectric slabs, when the incident angle is varied from normal incidence, or if a different periodicity with respect to the reference periodicity is adopted The generalized lumped parameters are included in an equivalent transmission line for computing the response of generic frequency-selective-surface configurations with no additional computational effort The results obtained through the simplified model presented here are verified by a careful comparison with MoM simulations

315 citations


01 Jan 2012
TL;DR: In this article, a Matlab/SIMULINK model of a photovoltaic cell was developed for the prediction of PV cell behavior under different physical and environmental parameters, which can also be used to extract the physical parameters for a given solar PV cell as a function of temperature and solar radiation.
Abstract: This paper focuses on a Matlab/SIMULINK model of a photovoltaic cell. This model is based on mathematical equations and is described through an equivalent circuit including a photocurrent source, a diode, a series resistor and a shunt resistor. The developed model allows the prediction of PV cell behaviour under different physical and environmental parameters. The model can also be used to extract the physical parameters for a given solar PV cell as a function of temperature and solar radiation. In addition, this study outlines the working principle of PV module as well as PV array. In order to validate the developed model, an experimental test bench was built and the obtained results exhibited a good agreement with the simulation ones. Keywords-Matlab, SIMULINK, PV, solar cell model, solar array model, solar radiation, maximum power point

275 citations


Journal ArticleDOI
TL;DR: In this article, an ultrathin and broadband radar absorber comprising single-layer resistive frequency selective surface (FSS) is investigated, which can provide a 10dB radar cross section reduction for the conducting plate over the frequency range of 10.7-29 GHz, which is equivalent to a relative bandwidth of 92.2%.
Abstract: An ultrathin and broadband radar absorber comprising single-layer resistive frequency selective surface (FSS) is investigated in this letter. The resistive FSS layer constructed from resistive/low-conductivity treble-square loops is backed by a grounded foam material. Numerical results show that the proposed absorber can provide a 10-dB radar cross section (RCS) reduction for the conducting plate over the frequency range of 10.7-29 GHz, which is equivalent to a relative bandwidth of 92.2%. Moreover, the structure has the thickness of 2 mm (only 0.071 to 0.193 at lowest and highest frequencies, respectively). The equivalent circuit model is then used to introduce the working principles of the proposed absorber.

229 citations


Journal ArticleDOI
TL;DR: Both qualitative analysis by equivalent circuit and accurate numeric calculation show that the coupling between the crisscross and the fractal square patch can enhance the bandwidth with the reflectivity below -10dB in the frequency range of 2-18GHz by producing a third absorption null.
Abstract: We report the design, fabrication, and measurement of a broadband metamaterial absorber, which consists of lossy frequency selective surface (FSS) and a metallic ground plane separated by a dielectric layer. The compact single unit cell of the FSS contains crisscross and fractal square patch which couple with each other. Both qualitative analysis by equivalent circuit and accurate numeric calculation show that the coupling between the crisscross and the fractal square patch can enhance the bandwidth with the reflectivity below −10dB in the frequency range of 2-18GHz by producing a third absorption null. In the end, the designed absorber was realized by experiment.

186 citations


Journal ArticleDOI
TL;DR: In this paper, the impedance spectra obtained at the temperatures between −−20°C and 20°C showed drastic change in sizes with shifting of the characteristic frequency of the impedance response of solid electrolyte interphase.

185 citations


Journal ArticleDOI
TL;DR: In this article, the stability analysis of a bidirectional dual full-bridge dc-dc converter with triple phase-shift control under arbitrary parameter changes is presented, and the Lyapunov function is used to determine the stability of the converter in every stage.
Abstract: This paper proposes a new method for stability analysis of a bidirectional dual full-bridge dc-dc converter with triple phase-shift control under arbitrary parameter changes. The present analysis makes the stability determination of these power converters more systematic and precise than the existing methods in this field, which are largely based on simulation. Nonlinear and periodic operation of the bidirectional converter is presented including the control circuit. Using the working theory, the converter operation is separated into several stages. Equivalent circuits and state equations are developed for each stage. The Lyapunov function method is used to determine the stability of the converter in every stage. Justification is provided for the absence of abrupt changes of the state variables or infinite noise at the interface of different stages. The stability of the bidirectional converter is determined theoretically by integrating these concepts. Some simulation results are provided to validate the developments.

Journal ArticleDOI
TL;DR: In this paper, a solution for reducing the radar cross section of a microstrip antenna based on the use of frequency selective surfaces (FSSs) is described, which is accomplished by replacing the solid ground plane of the device with a hybrid structure comprising a suitable FSS.
Abstract: A solution for reducing the radar cross section (RCS) of a microstrip antenna based on the use of frequency selective surfaces (FSSs) is described. The goal is accomplished by replacing the solid ground plane of the device with a hybrid structure comprising a suitable FSS. The behavior of the hybrid ground plane illuminated by a plane wave is analyzed by using a periodic method of moments (PMM), and it is modeled by resorting to a transmission-line equivalent circuit. Similarly, the propagation of the quasi-TEM mode along the modified feeding line of the array is represented by an equivalent circuit for surface waves. The two simplified analyses provide useful design criteria for the hybrid ground structure. The presented solution guarantees a decrease of the out-of-band radar signature of the target while preserving the desired in-band radiation characteristics of the low-profile array. A careful comparison to alternative configurations employing different ground planes has revealed the superior performance of the proposed design. Measurements on a realized prototype show a good agreement with simulations and prove the reliability of the design approach.

Journal ArticleDOI
TL;DR: In this article, a MATLAB/Simulink model of a photovoltaic cell is presented, which allows the prediction of PV cell behavior under different physical and environmental parameters.
Abstract: This paper focuses on a MATLAB/Simulink model of a photovoltaic cell. This model is based on mathematical equations and is described through an equivalent circuit including a photocurrent source, a diode, a series resistor and a shunt resistor.The developed model allows the prediction of PV cell behavior under different physical and environmental parameters. The model can also be used to extract the physical parameters for a given solar PV cell as a function of temperature and solar radiation. In addition, this study outlines the working principle of PV module as well as PV array.In order to validate the developed model, an experimental test bench was built and the obtained results exhibited a good agreement with the simulation ones.

Journal ArticleDOI
TL;DR: In this paper, an electronically reconfigurable unit cell with 1-bit phase quantization (0°/180°) is proposed for X-band linear polarization transmit arrays, which consists of two rectangular patch antennas loaded by U- and O-slots and connected by a metallized via-hole.
Abstract: An electronically reconfigurable unit cell with 1-bit phase quantization (0°/180°) is proposed for X-band linear polarization transmit arrays. It consists of two rectangular patch antennas loaded by U- and O-slots and connected by a metallized via-hole. The transmission phase is controlled using two p-i-n diode switches integrated in the O-slot. An equivalent lumped-element circuit model is implemented and compared successfully to full-wave simulations. The numerical results are validated experimentally using an ad-hoc waveguide simulator. The prototype exhibits low insertion loss (1.8 dB) with the same level for both phase states, a broad 3-dB transmission bandwidth (14.7%), a 1-dB compression point of 13-15 dBm, and a gain of 5 dBi at 9.75 GHz. The performance and simplicity of the proposed unit cell make it attractive to build electronically steerable transmit arrays in X-band.

Journal ArticleDOI
TL;DR: In this article, an equivalent circuit was designed for the analysis of lithium ion batteries with the contributions of a variety of diffusion parameters resulting from the various particle sizes for the cathode and the solid-electrolyte interphase formed on the anode particles, as well as electrochemical reactions and inductive components.

Journal ArticleDOI
TL;DR: In this paper, anisotropic impedance surfaces are employed as low-profile and broadband reflectors that convert orthogonal linear to right and left-handed circular polarization respectively, and a prototype is designed and its performance characteristics are evaluated.
Abstract: Anisotropic impedance surfaces are employed as low-profile and broadband reflectors that convert orthogonal linear to right- and left-handed circular polarization respectively. By virtue of anisotropy, it is possible to independently control the reflection characteristics of two orthogonal linearly polarized incident plane waves and therefore achieve linear to circular polarization conversion. Equivalent circuits for anisotropic impedance surfaces with arbitrarily shaped elements are employed to demonstrate the operating principle and a design procedure is proposed. The proposed design procedure is demonstrated by means of an example involving a dipole array. A prototype is designed and its performance characteristics are evaluated. The 3-dB relative axial ratio bandwidth exceeds 60%, while low loss and angular stability are also reported. Numerical and experimental results on a fabricated prototype are presented to validate the synthesis and the performance.

Journal ArticleDOI
TL;DR: This paper proposes an optimal design method in an asymmetric wireless power transfer (WPT) system for a 150 watt LED TV with three self-resonators, and a calculation method for mutual inductance in the system is expressed.
Abstract: This paper proposes an optimal design method in an asymmetric wireless power transfer (WPT) system for a 150 watt LED TV. The WPT system has three self-resonators: a Tx resonator, an Rx resonator, and an intermediate resonator. The Tx and Rx resonators are perpendicular and offset, respectively, to the intermediate resonator in the geometry. For optimal design, the WPT system is analyzed using an equivalent circuit. In particular, a calculation method for mutual inductance in the system is expressed. The calculation results of mutual inductance are used to determine the optimal position of each self-resonator for maximizing the power transfer efficiency. For verification, a WPT system for a 150 watt, 47 inch LED TV is fabricated at 250 kHz. The WPT system exhibits wireless power transfer efficiency of 80%.

Journal ArticleDOI
TL;DR: A rigorous structure of the fundamental equivalent circuit for photoelectrochemical water splitting systems is provided including a new predicted feature that is a chemical capacitance of the minority carriers that can give rise, in combination with other standard features, to a total of three arcs in the complex plane.
Abstract: A simple model for the kinetics of electrons and holes in a thin semiconductor film in photoelectrochemical water splitting conditions is discussed, with a focus to discriminate between trap-assisted recombination and charge-transfer processes. We formulate the kinetic model in terms of the measurements of impedance spectroscopy and discuss the application of the results for the interpretation of the current potential curve under photogeneration. We provide a rigorous structure of the fundamental equivalent circuit for photoelectrochemical water splitting systems including a new predicted feature that is a chemical capacitance of the minority carriers that can give rise, in combination with other standard features, to a total of three arcs in the complex plane.

Journal ArticleDOI
TL;DR: In this paper, an equivalent circuit for the analysis of the interaction between an electromagnetic field and a thin graphene sheet is derived, based on a local anisotropic model of the graphene conductivity, valid at frequencies below the THz range.
Abstract: An equivalent circuit for the analysis of the interaction between an electromagnetic field and a thin graphene sheet is derived, based on a local anisotropic model of the graphene conductivity, valid at frequencies below the THz range. Due to the anisotropic properties, the equivalent circuit is a four-port network which couples the fundamental TE and TM polarizations. The possible effects of electrostatic and/or magnetostatic bias are included and the equivalent circuit is next used to investigate the shielding properties of graphene layers against impinging plane waves. While the possibility of tuning the graphene conductivity leads to interesting properties of electronic control of shielding perfomance, the proposed equivalent circuit represents a very simple tool for the relevant analysis and design.

Journal ArticleDOI
TL;DR: In this paper, an equivalent circuit model was proposed to describe S-shaped current-voltage characteristics in inverted solar cells with a TiOx interlayer between the cathode and the poly(3-hex...
Abstract: In this study we propose an equivalent circuit model to describe S-shaped current–voltage (I–V) characteristics in inverted solar cells with a TiOx interlayer between the cathode and the poly(3-hex...

Journal ArticleDOI
Hui Yu1, Wim Bogaerts1
TL;DR: An equivalent circuit model for the coplanar waveguide (CPW) which serves as the traveling wave electrode to drive carrier-depletion-based silicon modulators is proposed in this article.
Abstract: We propose an equivalent circuit model for the coplanar waveguide (CPW) which serves as the traveling wave electrode to drive carrier-depletion-based silicon modulators. Conformal mapping and partial capacitance techniques are employed to calculate each element of the circuit. The validity of the model is confirmed by the comparison with both finite-element simulation and experimental result. With the model, we calculate the modulation bandwidth for different CPW dimensions and termination impedances. A 3 dB modulation bandwidth of 15 GHz is demonstrated with a traveling wave electrode of 3 mm. The calculation indicates that, by utilizing a traveling wave electrode of 2 mm, we can obtain a 3 dB modulation bandwidth of 28 GHz.

Journal ArticleDOI
TL;DR: In this article, a semi-empirical model for InGaP/InGaAs/Ge triple-junction cells is presented, which is calibrated against available empirical data published by two cell manufacturers.

Journal ArticleDOI
TL;DR: In this paper, a behavioral average circuit model of a switched capacitor converter (SCC) is proposed and demonstrated by a unity conversion SCC, which can be used to calculate or simulate the average values of the SCC variables such as output voltage, capacitor voltages, and subcircuit currents.
Abstract: A generic behavioral average circuit model of a switched capacitor converter (SCC) is proposed and demonstrated by a unity conversion SCC The model is based on the average currents concept and can be used to calculate or simulate the average values of the SCC variables such as output voltage, capacitor voltages, and subcircuit currents The model is valid for all operational ranges of an SCC (complete, partial, and no charge) and is compatible with any circuit simulator that includes dependent sources Excellent agreement was found between full switched-circuit simulation, average simulation by proposed model, and experimental results

Journal ArticleDOI
TL;DR: In this article, a trap-and-measure device is used to analyze the characteristics of electrochemical materials for biomedical applications, and four kinds of cell (HeLa, A549, MCF-7, and MDA-MB-231) are analyzed and characterized based on their impedance.
Abstract: Electrical impedance spectroscopy (EIS) is used to analyze the characteristics of electrochemical materials for biomedical applications. This paper presents a method for differentiating four kinds of cell using impedance measurements at various voltages and frequencies. Four kinds of cell (HeLa, A549, MCF-7, and MDA-MB-231) are analyzed and characterized based on their impedance by a trap-and-measure device. The impedance spectra are obtained by the impedance analyzer at an operating voltage of 0.2–1.0 V and frequency of 20–101 kHz. According to the impedance measurements, HeLa, A549, and MCF-7 cells and the pathological stages of a given cancer cell line (MCF-7 and MDA-MB-231) can be distinguished. The equivalent circuit is modeled as a cell impedance in parallel with the impedance of the culture medium, a cell impedance that contains the cell membrane capacitance, and a cytoplasm resistance. With an increase in the operating voltage, the cytoplasm resistance decreases due to the opening of the ionic channel. For A549, MDA-MB-231, MCF-7, and HeLa cells, the maximum variation of the resistance was obtained in the voltage ranges of 0.8–1.0 V, 0.8–1.0 V, 0.6–0.8 V, and 0.4–0.6 V, respectively. The results reveal that different kinds of cell have different tolerances to an electric field.

Journal ArticleDOI
TL;DR: In this article, the authors quantitatively investigated the elementary polarizations of a lithium-ion battery below room temperature in an attempt to determine the critical factors affecting low temperature power decline, and they proved that the interfacial charge transfer resistances of the anode (graphite) and the cathode (lithium cobalt dioxide) make the highest contributions to the low-temperature power decline.

Journal ArticleDOI
TL;DR: This paper analyzes a 90-kW brushless doubly fed three-phase induction machine in which a wound rotor circuit is connected to a rotary transformer and presents the advantages of substituting brushes and slip rings by aRotary transformer.
Abstract: This paper analyzes a 90-kW brushless doubly fed three-phase induction machine in which a wound rotor circuit is connected to a rotary transformer. It presents the advantages of substituting brushes and slip rings by a rotary transformer. In addition, it shows the rotary transformer design and presents the doubly fed induction machine operation. The steady-state model considers electrical circuit techniques to provide information about current, power factor, and efficiency on load. Equivalent circuit parameters are obtained through laboratory tests under a prototype. Comparisons between simulation and measurement results attest the good performance of the adopted model.

Journal ArticleDOI
TL;DR: The relations between the discharge current j(R)(t), the transferred charge q(t), and the measurable parameters are presented in new forms, which enable the qualitative interpretation of the measured current and voltage waveforms without the knowledge about the value of the dielectric barrier capacitance C(d).
Abstract: The concept of the simplest equivalent circuit for a dielectric barrier discharge (DBD) is critically reviewed. It is shown that the approach is consistent with experimental data measured either in large-scale sinusoidal-voltage driven or miniature pulse-voltage driven DBDs. An expression for the charge transferred through the gas gap q(t) is obtained with an accurate account for the displacement current and the values of DBD reactor capacitance. This enables (i) the significant reduction of experimental error in the determination of q(t) in pulsed DBDs, (ii) the verification of the classical electrical theory of ozonizers about maximal transferred charge qmax, and (iii) the development of a graphical method for the determination of qmax from charge-voltage characteristics (Q-V plots, often referred as Lissajous figures) measured under pulsed excitation. The method of graphical presentation of qmax is demonstrated with an example of a Q-V plot measured under pulsed excitation. The relations between the di...

Journal ArticleDOI
TL;DR: This paper describes a correction and an extension in the previously published large signal equivalent circuit model for a circular capacitive micromachined ultrasonic transducer (CMUT) cell that is able to predict the entire behavior of CMUT until the membrane touches the substrate.
Abstract: This paper describes a correction and an extension in the previously published large signal equivalent circuit model for a circular capacitive micromachined ultrasonic transducer (CMUT) cell The force model is rederived so that the energy and power is preserved in the equivalent circuit model The model is able to predict the entire behavior of CMUT until the membrane touches the substrate Many intrinsic properties of the CMUT cell, such as the collapse condition, collapse voltage, the voltage–displacement interrelation and the force equilibrium before and after collapse voltage in the presence of external static force, are obtained as a direct consequence of the model The small signal equivalent circuit for any bias condition is obtained from the large signal model The model can be implemented in circuit simulation tools and model predictions are in excellent agreement with finite element method simulations

Journal ArticleDOI
TL;DR: In this paper, a double periodic composite right/left-handed (CRLH) substrate integrated waveguide (SIW) is proposed based on the transmission line theory, and a new leaky-wave radiation is observed at low frequency below the left-handed passband.
Abstract: A double periodic composite right/left-handed ( DP-CRLH ) substrate integrated waveguide (SIW) is proposed based on the transmission line theory. A new leaky-wave radiation is observed at low frequency below the left-handed passband in addition to the composite right/left-handed property. First, the equivalent circuit of the proposed structure is analyzed, and dispersion characteristics are obtained including the expression for the cutoff frequencies. It is noted that transmission lines double periodically loaded with either alternate capacitances, or alternate inductances will contribute the new leaky-wave behavior. Next, SIW implementation of a DP-CRLH transmission line is designed and illustrated with simulated and experimentally demonstrated results. The electric field distribution plots are extracted from a full-wave simulation tool and exhibit the forward and backward wave propagation in the new leaky-wave region and the typical left-handed region, respectively. Finally, a compact leaky-wave antenna based on the DP-CRLH SIW is designed, and the radiation characteristics are tested and demonstrated to exhibit forward radiation at the new leaky-wave region from 5.2 to 5.8 GHz (covering IEEE 802.11a band) and frequency scanning from backward to forward directions in the left-handed and conventional right-handed region from 12.6 to 17.8 GHz.

Journal ArticleDOI
TL;DR: In this paper, a 15-cm monopole antenna was matched using a variable negative capacitance based on Linvill's balanced negative impedance converter, and the realized gain was improved by 10 dB relative to the unmatched case over 30-200 MHz.
Abstract: Non-Foster matching promises to improve the performance of electrically small antennas by tens of decibels over a decade of bandwidth, but only a few successful demonstrations have been reported in the literature. A 15-cm monopole antenna has been matched using a variable negative capacitance based on Linvill's balanced negative impedance converter. The realized gain is improved by >;10 dB relative to the unmatched case over 30-200 MHz. This letter reports the design, simulation, and measurement data and gives an equivalent circuit that can be used to synthesize future designs.