Online parameter identification is essential for the accuracy of the battery equivalent circuit model(ECM).The traditional recursive least squares(RLS)method is easily biased with the noise disturbances from sensors,w...Online parameter identification is essential for the accuracy of the battery equivalent circuit model(ECM).The traditional recursive least squares(RLS)method is easily biased with the noise disturbances from sensors,which degrades the modeling accuracy in practice.Meanwhile,the recursive total least squares(RTLS)method can deal with the noise interferences,but the parameter slowly converges to the reference with initial value uncertainty.To alleviate the above issues,this paper proposes a co-estimation framework utilizing the advantages of RLS and RTLS for a higher parameter identification performance of the battery ECM.RLS converges quickly by updating the parameters along the gradient of the cost function.RTLS is applied to attenuate the noise effect once the parameters have converged.Both simulation and experimental results prove that the proposed method has good accuracy,a fast convergence rate,and also robustness against noise corruption.展开更多
Lithium-oxygen batteries are a promising technology because they can greatly surpass the energy density of lithium-ion batteries.However,this theoretical characteristic has not yet been converted into a real device wi...Lithium-oxygen batteries are a promising technology because they can greatly surpass the energy density of lithium-ion batteries.However,this theoretical characteristic has not yet been converted into a real device with high cyclability.Problems with air contamination,metallic lithium reactivity,and complex discharge and charge reactions are the main issues for this technology.A fast and reversible oxygen reduction reaction(ORR)is crucial for good performance of secondary batteries',but the partial knowledge of its mechanisms,especially when devices are concerned,hinders further development.From this perspective,the present work uses operando Raman experiments and electrochemical impedance spectroscopy(EIS)to assess the first stages of the discharge processes in porous carbon electrodes,following their changes cycle by cycle at initial operation.A growth kinetic formation of the discharge product signal(Li_(2)O_(2))was observed with operando Raman,indicating a first-order reaction and enabling an analysis by a microkinetic model.The solution mechanism in the evaluated system was ascribed for an equivalent circuit with three time constants.While the time constant for the anode interface reveals to remain relatively constant after the first discharge,its surface seemed to be more non-uniform.The model indicated that the reaction occurs at the Li_(2)O_(2) surface,decreasing the associated resistance during the initial discharge phase.Furthermore,the growth of Li_(2)O_(2) forms a hetero-phase between Li_(2)O_(2)/electrolyte,while creating a more compact and homogeneous on the Li_(2)O_(2)/cathode surface.The methodology here described thus offers a way of directly probing changes in surface chemistry evolution during cycling from a device through EIS analysis.展开更多
Very high-energy electrons(VHEEs)are potential candidates for FLASH radiotherapy for deep-seated tumors.We proposed a compact VHEE facility based on an X-band high-gradient high-power technique.In this study,we invest...Very high-energy electrons(VHEEs)are potential candidates for FLASH radiotherapy for deep-seated tumors.We proposed a compact VHEE facility based on an X-band high-gradient high-power technique.In this study,we investigated and realized the first X-band backward traveling-wave(BTW)accelerating structure as the buncher for a VHEE facility.A method for calculating the parameters of single cell from the field distribution was introduced to simplify the design of the BTW structure.Time-domain circuit equations were applied to calculate the transient beam parameters of the buncher in the unsteady state.A prototype of the BTW structure with a thermionic cathode-diode electron gun was designed,fabricated,and tested at high power at the Tsinghua X-band high-power test stand.The structure successfully operated with 5-MW microwave pulses from the pulse compressor and outputted electron bunches with an energy of 8 MeV and a pulsed current of 108 mA.展开更多
This article contains the description of a circuital model, which was developed to represent the energy production of a photovoltaic panel in a more accurate way, taking into consideration the decrease of its operatio...This article contains the description of a circuital model, which was developed to represent the energy production of a photovoltaic panel in a more accurate way, taking into consideration the decrease of its operational time. Furthermore, a comparison among the experimental, the posed simulated model in PSIM and the results obtained by a piece of software developed by some students of the Universidad Distrital is performed in order to verify the values provided by the software and demonstrate the optimal operation of the developed model.展开更多
Based on the fact that the real inductor and the real capacitor are fractional order in nature and the fractional calculus,the transfer function modeling and analysis of the open-loop Buck converter in a continuous co...Based on the fact that the real inductor and the real capacitor are fractional order in nature and the fractional calculus,the transfer function modeling and analysis of the open-loop Buck converter in a continuous conduction mode(CCM) operation are carried out in this paper.The fractional order small signal model and the corresponding equivalent circuit of the open-loop Buck converter in a CCM operation are presented.The transfer functions from the input voltage to the output voltage,from the input voltage to the inductor current,from the duty cycle to the output voltage,from the duty cycle to the inductor current,and the output impedance of the open-loop Buck converter in CCM operation are derived,and their bode diagrams and step responses are calculated,respectively.It is found that all the derived fractional order transfer functions of the system are influenced by the fractional orders of the inductor and the capacitor.Finally,the realization of the fractional order inductor and the fractional order capacitor is designed,and the corresponding PSIM circuit simulation results of the open-loop Buck converter in CCM operation are given to confirm the correctness of the derivations and the theoretical analysis.展开更多
The current research of state of charge(SoC) online estimation of lithium-ion battery(LiB) in electric vehicles(EVs)mainly focuses on adopting or improving of battery models and estimation filters. However, little att...The current research of state of charge(SoC) online estimation of lithium-ion battery(LiB) in electric vehicles(EVs)mainly focuses on adopting or improving of battery models and estimation filters. However, little attention has been paid to the accuracy of various open circuit voltage(OCV) models for correcting the SoC with aid of the ampere-hour counting method. This paper presents a comprehensive comparison study on eighteen OCV models which cover the majority of models used in literature. The low-current OCV tests are conducted on the typical commercial LiFePO/graphite(LFP) and LiNiMnCoO/graphite(NMC) cells to obtain the experimental OCV-SoC curves at different ambient temperature and aging stages. With selected OCV and SoC points from experimental OCV-SoC curves, the parameters of each OCV model are determined by curve fitting toolbox of MATLAB 2013. Then the fitting OCV-SoC curves based on diversified OCV models are also obtained. The indicator of root-mean-square error(RMSE) between the experimental data and fitted data is selected to evaluate the adaptabilities of these OCV models for their main features, advantages,and limitations. The sensitivities of OCV models to ambient temperatures, aging stages, numbers of data points,and SoC regions are studied for both NMC and LFP cells. Furthermore, the influences of these models on SoC estimation are discussed. Through a comprehensive comparison and analysis on OCV models, some recommendations in selecting OCV models for both NMC and LFP cells are given.展开更多
A circuit model of the Amperometric immunosensor for use in the biosensor system-on-chip simulation is proposed in this paper.The model parameters are extracted with several methods and verified by MATLAB and SPICE si...A circuit model of the Amperometric immunosensor for use in the biosensor system-on-chip simulation is proposed in this paper.The model parameters are extracted with several methods and verified by MATLAB and SPICE simulation.A CMOS potentiostat circuit required for conditioning the Amperometric immunosensor is also included in the circuit model.The mean square error norm of the simulated curve against the measured one is 8.65×10^(-17) The whole circuit has been fabricated in a 0.35μm CMOS process.展开更多
The industrial application of the Kaufman ion thruster in its arc stage is limited owing to the instability of the discharge pulse.Presently,a complete prediction model that can predict the discharge pulse in the high...The industrial application of the Kaufman ion thruster in its arc stage is limited owing to the instability of the discharge pulse.Presently,a complete prediction model that can predict the discharge pulse in the high-current stage does not exist.In this study,a complete prediction model for the pulse in the ion thruster is established using the zero-dimensional plasma discharge model and equivalent circuit model.The zero-dimensional plasma discharge model is used to obtain the corresponding plasma parameters by calculating the beam current,discharge current,voltage,and gas flow under actual working conditions.The input parameters of the equivalent circuit model are calculated using empirical formulae to acquire the estimated discharge waveforms.The pulse waveforms obtained using the model are found to be consistent with the experimental results.The model is used to evaluate the process of rapid changes in plasma density.Additionally,this model is employed to predict changes in the pulse waveforms when the volume of the discharge chamber and grid plate transmittance are changed.展开更多
The capacitively coupled radio frequency(CCRF)plasma has been widely used in various fields.In some cases,it requires us to estimate the range of key plasma parameters simpler and quicker in order to understand the ...The capacitively coupled radio frequency(CCRF)plasma has been widely used in various fields.In some cases,it requires us to estimate the range of key plasma parameters simpler and quicker in order to understand the behavior in plasma.In this paper,a glass vacuum chamber and a pair of plate electrodes were designed and fabricated,using 13.56 MHz radio frequency(RF)discharge technology to ionize the working gas of Ar.This discharge was mathematically described with equivalent circuit model.The discharge voltage and current of the plasma were measured atdifferent pressures and different powers.Based on the capacitively coupled homogeneous discharge model,the equivalent circuit and the analytical formula were established.The plasma density and temperature were calculated by using the equivalent impedance principle and energy balance equation.The experimental results show that when RF discharge power is 50–300 W and pressure is 25–250 Pa,the average electron temperature is about 1.7–2.1 e V and the average electron density is about 0.5?×10^17–3.6?×10^17m^-3.Agreement was found when the results were compared to those given by optical emission spectroscopy and COMSOL simulation.展开更多
With the progress of the semiconductor industry, resistive memories, especially the memristor, have drawn increasing attention. The resistive memory based on memrsitor has not been commercialized mainly because of dat...With the progress of the semiconductor industry, resistive memories, especially the memristor, have drawn increasing attention. The resistive memory based on memrsitor has not been commercialized mainly because of data error. Currently, there are more studies focused on fault tolerance of resistive memory. This paper studies the resistive switching mechanism which may have time-varying characteristics. Resistive switching mechanism is analyzed and its respective circuit model is established based on the memristor Spice model.展开更多
This paper reports a novel analytic model of this multichannel spark discharge, considering the delay time in the breakdown process, the electric transforming of the discharge channel from a capacitor to a resistor in...This paper reports a novel analytic model of this multichannel spark discharge, considering the delay time in the breakdown process, the electric transforming of the discharge channel from a capacitor to a resistor induced by the air breakdown, and the varying plasma resistance in the discharge process. The good agreement between the experimental and the simulated results validated the accuracy of this model. Based on this model, the influence of the circuit parameters on the maximum discharge channel number(MDCN) is investigated. Both the input voltage amplitude and the breakdown voltage threshold of each discharge channel play a critical role. With the increase of the input voltage and the decrease of the breakdown voltage, the MCDN increases almost linearly. With the increase of the discharge capacitance, the MDCN first rises and then remains almost constant. With the increase of the circuit inductance, the MDCN increases slowly but decreases quickly when the inductance increases over a certain value. There is an optimal value of the capacitor connected to the discharge channel corresponding to the MDCN. Finally, based on these results, to shorten the discharge time, a modified multichannel discharge circuit is developed and validated by the experiment. With only 6-kV input voltage, 31-channels discharge is achieved. The breakdown voltage of each electrode gap is larger than 3 kV. The modified discharge circuit is certain to be widely used in the PSJA flow control field.展开更多
In the parametric modeling of the circuit model for glow discharge in air,a new method for the design of glow discharge circuit model is presented.The new circuit model is an important reference for the design of plas...In the parametric modeling of the circuit model for glow discharge in air,a new method for the design of glow discharge circuit model is presented.The new circuit model is an important reference for the design of plasma power supply,the simulation of glow discharge plasma actuator and the simulation of glow discharge plasma anemometer.The modeling approach consists in developing an electrical model of the glow discharge in air based on circuit components.The structure of the circuit model is established according to the theoretical analysis and the experimental device.Then the parameters of the circuit model are obtained based on the circuit analysis.Finally,the circuit model is verified by comparing the simulation current with the experimental current.This model takes into account the whole framework of the air glow discharge including the sheath and the plasma area.The built circuit model is feasible and reliable,thus being instructive for the investigation of the glow discharge in air.展开更多
Terahertz quantum cascade lasers(THz QCLs) emitted at 4.4 THz are fabricated and characterized. An equivalent circuit model is established based on the five-level rate equations to describe their characteristics. In...Terahertz quantum cascade lasers(THz QCLs) emitted at 4.4 THz are fabricated and characterized. An equivalent circuit model is established based on the five-level rate equations to describe their characteristics. In order to illustrate the capability of the model, the steady and dynamic performances of the fabricated THz QCLs are simulated by the model.Compared to the sophisticated numerical methods, the presented model has advantages of fast calculation and good compatibility with circuit simulation for system-level designs and optimizations. The validity of the model is verified by the experimental and numerical results.展开更多
We present the variations of electrical parameters of dielectric barrier discharge(DBD)when the DBD generator is used for the material modification,whereas the relevant physical mechanism is also elaborated.An equival...We present the variations of electrical parameters of dielectric barrier discharge(DBD)when the DBD generator is used for the material modification,whereas the relevant physical mechanism is also elaborated.An equivalent circuit model is applied for a DBD generator working in a filament discharging mode,considering the addition of epoxy resin(EP)as the plasma modified material.The electrical parameters are calculated through the circuit model.The surface conductivity,surface potential decay,trap distributions and surface charge distributions on the EP surface before and after plasma treatments were measured and calculated.It is found that the coverage area of micro-discharge channels on the EP surface is increased with the discharging time under the same applied AC voltage.The results indicate that the plasma modified material could influence the ignition of new filaments in return during the modification process.Moreover,the surface conductivity and density of shallow traps with low trap energy of the EP samples increase after the plasma treatment.The surface charge distributions indicate that the improved surface properties accelerate the movement and redistribution of charge carriers on the EP surface.The variable electrical parameters of discharge are attributed to the redistribution of deposited surface charge on the plasma modified EP sample surface.展开更多
With the widespread utilization of indium-phosphide-based high-electron-mobility transistors(InP HEMTs)in the millimeter-wave(mmW)band,the distributed and high-frequency parasitic coupling behavior of the device is pa...With the widespread utilization of indium-phosphide-based high-electron-mobility transistors(InP HEMTs)in the millimeter-wave(mmW)band,the distributed and high-frequency parasitic coupling behavior of the device is particularly prominent.We present an InP HEMT extrinsic parasitic equivalent circuit,in which the conductance between the device electrodes and a new gate-drain mutual inductance term L_(mgd)are taken into account for the high-frequency magnetic field coupling between device electrodes.Based on the suggested parasitic equivalent circuit,through HFSS and advanced design system(ADS)co-simulation,the equivalent circuit parameters are directly extracted in the multi-step system.The HFSS simulation prediction,measurement data,and modeled frequency response are compared with each other to verify the feasibility of the extraction method and the accuracy of the equivalent circuit.The proposed model demonstrates the distributed and radio-frequency behavior of the device and solves the problem that the equivalent circuit parameters of the conventional InP HEMTs device are limited by the device model and inaccurate at high frequencies when being extracted.展开更多
With the progress of the semiconductor industry,the resistive random-access memory(RAM) has drawn increasing attention.The discovery of the memristor has brought much attention to this study.Research has focused on ...With the progress of the semiconductor industry,the resistive random-access memory(RAM) has drawn increasing attention.The discovery of the memristor has brought much attention to this study.Research has focused on the resistive switching characteristics of different materials and the analysis of resistive switching mechanisms.We discuss the resistive switching mechanisms of different materials in this paper and analyze the differences of those mechanisms from the view point of circuitry to establish their respective circuit models.Finally,simulations are presented.We give the prospect of using different materials in resistive RAM on account of their resistive switching mechanisms,which are applied to explain their resistive switchings.展开更多
This study presents the deduction of time domain mathematical equations to simulate the curve of the charging process of a symmetrical electrochemical supercapacitor with activated carbon electrodes fed by a source of...This study presents the deduction of time domain mathematical equations to simulate the curve of the charging process of a symmetrical electrochemical supercapacitor with activated carbon electrodes fed by a source of constant electric potential in time ε and the curve of the discharge process through two fixed resistors. The first resistor R<sub>Co</sub> is a control that aims to prevent sudden variations in the intensity of the electric current i<sub>1</sub>(t) present at the terminals of the electrochemical supercapacitor at the beginning of the charging process. The second resistor is the internal resistance R<sub>A</sub> of the ammeter used in the calculation of the intensity of the electric current i<sub>1</sub>(t) over time in the charging and discharging processes. The mathematical equations generated were based on a 2R(C + kU<sub>C</sub>(t)) electrical circuit model and allowed to simulate the effects of the potential-dependent capacitance (kU<sub>C</sub>(t)) on the charge and discharge curves and hence on the calculated values of the fixed capacitance C, the equivalent series resistance (ESR), the equivalent parallel resistance (EPR) and the electrical potential dependent capacitance index k.展开更多
An earlier study manipulated the Butler-Volmer equation to effectively model a lithium-ion capacitor’s (LIC) energy storage as a function of its constituent components and charge current. However, this model had seve...An earlier study manipulated the Butler-Volmer equation to effectively model a lithium-ion capacitor’s (LIC) energy storage as a function of its constituent components and charge current. However, this model had several shortcomings: computed temperature values were too low, voltage was inaccurate, and the model required Warburg impedance values that were two orders of magnitude higher than experimental results. This study began by analyzing the model’s temperature and voltage computations in order to justify output values. Ultimately, these justifications failed. Therefore, in situ temperature rise was measured during charge cycles. Experimental results indicated that temperature increases minimally during a charge cycle (<1%). At high current densities (≥150 A<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>) temperature increase is negligible. After it was found that LIC temperature change is minimal during a charge cycle, the model accurately computed LIC voltage during the charge cycle and computed Warburg impedance that agreed with values derived from earlier experimental studies, even falling within the measurements’ precision error.展开更多
An analytical model for current-voltage behavior of amorphous In-Ga-Zn-O thin-film transistors(a-IGZO TFTs)with dual-gate structures is developed.The unified expressions for synchronous and asynchronous operating mo...An analytical model for current-voltage behavior of amorphous In-Ga-Zn-O thin-film transistors(a-IGZO TFTs)with dual-gate structures is developed.The unified expressions for synchronous and asynchronous operating modes are derived on the basis of channel charges,which are controlled by gate voltage.It is proven that the threshold voltage of asynchronous dual-gate IGZO TFTs is adjusted in proportion to the ratio of top insulating capacitance to the bottom insulating capacitance(C_(TI)/C_(BI)).Incorporating the proposed model with Verilog-A,a touch-sensing circuit using dual-gate structure is investigated by SPICE simulations.Comparison shows that the touch sensitivity is increased by the dual-gate IGZO TFT structure.展开更多
This paper presents a numerical analysis for computation of free space capacitance of different arbitrarily shaped conducting bodies based on the finite element method with triangular subsection modeling. Evaluation o...This paper presents a numerical analysis for computation of free space capacitance of different arbitrarily shaped conducting bodies based on the finite element method with triangular subsection modeling. Evaluation of capacitance of different arbitrary shapes is important for the electrostatic analysis. Capacitance computation is an important step in the prediction of electrostatic discharge which causes electromagnetic interference. We specifically illustrated capacitance computation of electrostatic models like unit cube, rectangular plate, triangular plate, T-shaped plate, sphere and two touching spheres. Numerical data on the capacitance of conducting objects are presented. The results are compared with other available results in the literature. We used the COMSOL Multiphysics software for the simulation. The models are designed in three-dimensional form using electrostatic environment and can be applied to any spacecraft circuit modeling design. The findings of this study show that the finite element method is a more accurate method and can be applied to any circuit modeling design.展开更多
基金National Natural Science Foundation of China(Grant No.52107229)the Fund of Robot Technology Used for Special Environment Key Laboratory of Sichuan Province(Grant No.20KFKT02)。
文摘Online parameter identification is essential for the accuracy of the battery equivalent circuit model(ECM).The traditional recursive least squares(RLS)method is easily biased with the noise disturbances from sensors,which degrades the modeling accuracy in practice.Meanwhile,the recursive total least squares(RTLS)method can deal with the noise interferences,but the parameter slowly converges to the reference with initial value uncertainty.To alleviate the above issues,this paper proposes a co-estimation framework utilizing the advantages of RLS and RTLS for a higher parameter identification performance of the battery ECM.RLS converges quickly by updating the parameters along the gradient of the cost function.RTLS is applied to attenuate the noise effect once the parameters have converged.Both simulation and experimental results prove that the proposed method has good accuracy,a fast convergence rate,and also robustness against noise corruption.
基金supported by the S?o Paulo Research Foundation (FAPESP) (2017/11958-1)the strategic importance of the support given by ANP (Brazil's National Oil,Natural Gas and Biofuels Agency)through the R&D levy regulation and the support from the Brazilian Coordination for the Improvement of Higher Education and Personnel (CAPES)CNPq (PQ-2 grant:Process 304442/2019-4 and UFMT STI-Server for access to their computing resources)。
文摘Lithium-oxygen batteries are a promising technology because they can greatly surpass the energy density of lithium-ion batteries.However,this theoretical characteristic has not yet been converted into a real device with high cyclability.Problems with air contamination,metallic lithium reactivity,and complex discharge and charge reactions are the main issues for this technology.A fast and reversible oxygen reduction reaction(ORR)is crucial for good performance of secondary batteries',but the partial knowledge of its mechanisms,especially when devices are concerned,hinders further development.From this perspective,the present work uses operando Raman experiments and electrochemical impedance spectroscopy(EIS)to assess the first stages of the discharge processes in porous carbon electrodes,following their changes cycle by cycle at initial operation.A growth kinetic formation of the discharge product signal(Li_(2)O_(2))was observed with operando Raman,indicating a first-order reaction and enabling an analysis by a microkinetic model.The solution mechanism in the evaluated system was ascribed for an equivalent circuit with three time constants.While the time constant for the anode interface reveals to remain relatively constant after the first discharge,its surface seemed to be more non-uniform.The model indicated that the reaction occurs at the Li_(2)O_(2) surface,decreasing the associated resistance during the initial discharge phase.Furthermore,the growth of Li_(2)O_(2) forms a hetero-phase between Li_(2)O_(2)/electrolyte,while creating a more compact and homogeneous on the Li_(2)O_(2)/cathode surface.The methodology here described thus offers a way of directly probing changes in surface chemistry evolution during cycling from a device through EIS analysis.
基金supported by the National Natural Science Foundation of China(No.11922504).
文摘Very high-energy electrons(VHEEs)are potential candidates for FLASH radiotherapy for deep-seated tumors.We proposed a compact VHEE facility based on an X-band high-gradient high-power technique.In this study,we investigated and realized the first X-band backward traveling-wave(BTW)accelerating structure as the buncher for a VHEE facility.A method for calculating the parameters of single cell from the field distribution was introduced to simplify the design of the BTW structure.Time-domain circuit equations were applied to calculate the transient beam parameters of the buncher in the unsteady state.A prototype of the BTW structure with a thermionic cathode-diode electron gun was designed,fabricated,and tested at high power at the Tsinghua X-band high-power test stand.The structure successfully operated with 5-MW microwave pulses from the pulse compressor and outputted electron bunches with an energy of 8 MeV and a pulsed current of 108 mA.
文摘This article contains the description of a circuital model, which was developed to represent the energy production of a photovoltaic panel in a more accurate way, taking into consideration the decrease of its operational time. Furthermore, a comparison among the experimental, the posed simulated model in PSIM and the results obtained by a piece of software developed by some students of the Universidad Distrital is performed in order to verify the values provided by the software and demonstrate the optimal operation of the developed model.
基金Project supported by the National Natural Science Foundation of China (Grant No. 51007068)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20100201120028)+2 种基金the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2012JQ7026)the Fundamental Research Funds for the Central Universities of China (Grant No. 2012jdgz09)the State Key Laboratory of Electrical Insulation and Power Equipment of China (Grant No. EIPE12303)
文摘Based on the fact that the real inductor and the real capacitor are fractional order in nature and the fractional calculus,the transfer function modeling and analysis of the open-loop Buck converter in a continuous conduction mode(CCM) operation are carried out in this paper.The fractional order small signal model and the corresponding equivalent circuit of the open-loop Buck converter in a CCM operation are presented.The transfer functions from the input voltage to the output voltage,from the input voltage to the inductor current,from the duty cycle to the output voltage,from the duty cycle to the inductor current,and the output impedance of the open-loop Buck converter in CCM operation are derived,and their bode diagrams and step responses are calculated,respectively.It is found that all the derived fractional order transfer functions of the system are influenced by the fractional orders of the inductor and the capacitor.Finally,the realization of the fractional order inductor and the fractional order capacitor is designed,and the corresponding PSIM circuit simulation results of the open-loop Buck converter in CCM operation are given to confirm the correctness of the derivations and the theoretical analysis.
基金Supported by National Natural Science Foundation of China(Grant No.51507012)Beijing Municipal Natural Science Foundation of China(Grant No.3182035)
文摘The current research of state of charge(SoC) online estimation of lithium-ion battery(LiB) in electric vehicles(EVs)mainly focuses on adopting or improving of battery models and estimation filters. However, little attention has been paid to the accuracy of various open circuit voltage(OCV) models for correcting the SoC with aid of the ampere-hour counting method. This paper presents a comprehensive comparison study on eighteen OCV models which cover the majority of models used in literature. The low-current OCV tests are conducted on the typical commercial LiFePO/graphite(LFP) and LiNiMnCoO/graphite(NMC) cells to obtain the experimental OCV-SoC curves at different ambient temperature and aging stages. With selected OCV and SoC points from experimental OCV-SoC curves, the parameters of each OCV model are determined by curve fitting toolbox of MATLAB 2013. Then the fitting OCV-SoC curves based on diversified OCV models are also obtained. The indicator of root-mean-square error(RMSE) between the experimental data and fitted data is selected to evaluate the adaptabilities of these OCV models for their main features, advantages,and limitations. The sensitivities of OCV models to ambient temperatures, aging stages, numbers of data points,and SoC regions are studied for both NMC and LFP cells. Furthermore, the influences of these models on SoC estimation are discussed. Through a comprehensive comparison and analysis on OCV models, some recommendations in selecting OCV models for both NMC and LFP cells are given.
基金supported by National Natural Science Foundation of China,No.90307014
文摘A circuit model of the Amperometric immunosensor for use in the biosensor system-on-chip simulation is proposed in this paper.The model parameters are extracted with several methods and verified by MATLAB and SPICE simulation.A CMOS potentiostat circuit required for conditioning the Amperometric immunosensor is also included in the circuit model.The mean square error norm of the simulated curve against the measured one is 8.65×10^(-17) The whole circuit has been fabricated in a 0.35μm CMOS process.
基金the financial support from National Natural Science Foundation of China(Nos.11402025,11475019,and 11702123)the National Key Laboratory of Science and Technology on Vacuum Technology&Physics(No.ZWK1608)+1 种基金the Advanced Space Propulsion Laboratory of BICEBeijing Engineering Research Center of Efficient and Green Aerospace Propulsion Technology(No.Lab ASP-2018-03)。
文摘The industrial application of the Kaufman ion thruster in its arc stage is limited owing to the instability of the discharge pulse.Presently,a complete prediction model that can predict the discharge pulse in the high-current stage does not exist.In this study,a complete prediction model for the pulse in the ion thruster is established using the zero-dimensional plasma discharge model and equivalent circuit model.The zero-dimensional plasma discharge model is used to obtain the corresponding plasma parameters by calculating the beam current,discharge current,voltage,and gas flow under actual working conditions.The input parameters of the equivalent circuit model are calculated using empirical formulae to acquire the estimated discharge waveforms.The pulse waveforms obtained using the model are found to be consistent with the experimental results.The model is used to evaluate the process of rapid changes in plasma density.Additionally,this model is employed to predict changes in the pulse waveforms when the volume of the discharge chamber and grid plate transmittance are changed.
基金supported by National Natural Science Foundation of China(Grant No.61378037)the Fundamental Research Funds for the Central Universities(Nos.2013B33614,2017B15214)+1 种基金the Research Funds of Innovation and Entrepreneurship Education Reform for Chinese Universities(No.16CCJG01Z004)the Changzhou Science and Technology Program(No.CJ20160027)
文摘The capacitively coupled radio frequency(CCRF)plasma has been widely used in various fields.In some cases,it requires us to estimate the range of key plasma parameters simpler and quicker in order to understand the behavior in plasma.In this paper,a glass vacuum chamber and a pair of plate electrodes were designed and fabricated,using 13.56 MHz radio frequency(RF)discharge technology to ionize the working gas of Ar.This discharge was mathematically described with equivalent circuit model.The discharge voltage and current of the plasma were measured atdifferent pressures and different powers.Based on the capacitively coupled homogeneous discharge model,the equivalent circuit and the analytical formula were established.The plasma density and temperature were calculated by using the equivalent impedance principle and energy balance equation.The experimental results show that when RF discharge power is 50–300 W and pressure is 25–250 Pa,the average electron temperature is about 1.7–2.1 e V and the average electron density is about 0.5?×10^17–3.6?×10^17m^-3.Agreement was found when the results were compared to those given by optical emission spectroscopy and COMSOL simulation.
基金Project supported by the National Natural Science Foundation of China(Grant No.60921062)
文摘With the progress of the semiconductor industry, resistive memories, especially the memristor, have drawn increasing attention. The resistive memory based on memrsitor has not been commercialized mainly because of data error. Currently, there are more studies focused on fault tolerance of resistive memory. This paper studies the resistive switching mechanism which may have time-varying characteristics. Resistive switching mechanism is analyzed and its respective circuit model is established based on the memristor Spice model.
基金supported by the National Natural Science Foundation of China(Grant Nos.51336011,51522606,91541120,51611130198,51407197,and 11472306)Royal Society(Grant No.IE150612)
文摘This paper reports a novel analytic model of this multichannel spark discharge, considering the delay time in the breakdown process, the electric transforming of the discharge channel from a capacitor to a resistor induced by the air breakdown, and the varying plasma resistance in the discharge process. The good agreement between the experimental and the simulated results validated the accuracy of this model. Based on this model, the influence of the circuit parameters on the maximum discharge channel number(MDCN) is investigated. Both the input voltage amplitude and the breakdown voltage threshold of each discharge channel play a critical role. With the increase of the input voltage and the decrease of the breakdown voltage, the MCDN increases almost linearly. With the increase of the discharge capacitance, the MDCN first rises and then remains almost constant. With the increase of the circuit inductance, the MDCN increases slowly but decreases quickly when the inductance increases over a certain value. There is an optimal value of the capacitor connected to the discharge channel corresponding to the MDCN. Finally, based on these results, to shorten the discharge time, a modified multichannel discharge circuit is developed and validated by the experiment. With only 6-kV input voltage, 31-channels discharge is achieved. The breakdown voltage of each electrode gap is larger than 3 kV. The modified discharge circuit is certain to be widely used in the PSJA flow control field.
基金supported by the Natural Science Foundation of Jiangsu Province (No.BK20140820)the Fundamental Research Funds for the Central Universities (No.NJ20160037)+2 种基金the Natural Science Foundation of China(No.51406083)the Funding of Jiangsu Innovation Program for Graduate Education(No.SJZZ16_0055)the Fundamental Research Funds for the Central Universities
文摘In the parametric modeling of the circuit model for glow discharge in air,a new method for the design of glow discharge circuit model is presented.The new circuit model is an important reference for the design of plasma power supply,the simulation of glow discharge plasma actuator and the simulation of glow discharge plasma anemometer.The modeling approach consists in developing an electrical model of the glow discharge in air based on circuit components.The structure of the circuit model is established according to the theoretical analysis and the experimental device.Then the parameters of the circuit model are obtained based on the circuit analysis.Finally,the circuit model is verified by comparing the simulation current with the experimental current.This model takes into account the whole framework of the air glow discharge including the sheath and the plasma area.The built circuit model is feasible and reliable,thus being instructive for the investigation of the glow discharge in air.
基金Project supported by the National Basic Research Program of China(Grant No.2014CB339803)the National High Technology Research and Development Program of China(Grant No.2011AA010205)+5 种基金the National Natural Science Foundation of China(Grant Nos.61131006,61321492,and 61404149)the Major National Development Project of Scientific Instrument and Equipment,China(Grant No.2011YQ150021)the National Science and Technology Major Project,China(Grant No.2011ZX02707)the Major Project,China(Grant No.YYYJ-1123-1)the International Collaboration and Innovation Program on High Mobility Materials Engineering of the Chinese Academy of Sciencesthe Shanghai Municipal Commission of Science and Technology,China(Grant Nos.14530711300)
文摘Terahertz quantum cascade lasers(THz QCLs) emitted at 4.4 THz are fabricated and characterized. An equivalent circuit model is established based on the five-level rate equations to describe their characteristics. In order to illustrate the capability of the model, the steady and dynamic performances of the fabricated THz QCLs are simulated by the model.Compared to the sophisticated numerical methods, the presented model has advantages of fast calculation and good compatibility with circuit simulation for system-level designs and optimizations. The validity of the model is verified by the experimental and numerical results.
基金Project supported by the National Key R&D Program of China(Grant No.2018YFB0904400)the National Natural Science Foundation of China(Grant No.51977187)+3 种基金the“Science and Technology Innovation 2025”Key Project of Ningbo City,China(Grant No.2018B10019)the Natural Science Foundation of Zhejiang Province,China(Grant No.LY18E070003)the State Key Laboratory of HVDC,Electric Power Research Institute,China Southern Power Grid(Grant No.SKLHVDC-2019-KF-18)the Fundamental Research Funds for the Central Universities,China(Grant No.2018QNA4017).
文摘We present the variations of electrical parameters of dielectric barrier discharge(DBD)when the DBD generator is used for the material modification,whereas the relevant physical mechanism is also elaborated.An equivalent circuit model is applied for a DBD generator working in a filament discharging mode,considering the addition of epoxy resin(EP)as the plasma modified material.The electrical parameters are calculated through the circuit model.The surface conductivity,surface potential decay,trap distributions and surface charge distributions on the EP surface before and after plasma treatments were measured and calculated.It is found that the coverage area of micro-discharge channels on the EP surface is increased with the discharging time under the same applied AC voltage.The results indicate that the plasma modified material could influence the ignition of new filaments in return during the modification process.Moreover,the surface conductivity and density of shallow traps with low trap energy of the EP samples increase after the plasma treatment.The surface charge distributions indicate that the improved surface properties accelerate the movement and redistribution of charge carriers on the EP surface.The variable electrical parameters of discharge are attributed to the redistribution of deposited surface charge on the plasma modified EP sample surface.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61434006 and 61704189)the Fund from the Youth Innovation Promotion Association of the Chinese Academy of Sciences。
文摘With the widespread utilization of indium-phosphide-based high-electron-mobility transistors(InP HEMTs)in the millimeter-wave(mmW)band,the distributed and high-frequency parasitic coupling behavior of the device is particularly prominent.We present an InP HEMT extrinsic parasitic equivalent circuit,in which the conductance between the device electrodes and a new gate-drain mutual inductance term L_(mgd)are taken into account for the high-frequency magnetic field coupling between device electrodes.Based on the suggested parasitic equivalent circuit,through HFSS and advanced design system(ADS)co-simulation,the equivalent circuit parameters are directly extracted in the multi-step system.The HFSS simulation prediction,measurement data,and modeled frequency response are compared with each other to verify the feasibility of the extraction method and the accuracy of the equivalent circuit.The proposed model demonstrates the distributed and radio-frequency behavior of the device and solves the problem that the equivalent circuit parameters of the conventional InP HEMTs device are limited by the device model and inaccurate at high frequencies when being extracted.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60921062)
文摘With the progress of the semiconductor industry,the resistive random-access memory(RAM) has drawn increasing attention.The discovery of the memristor has brought much attention to this study.Research has focused on the resistive switching characteristics of different materials and the analysis of resistive switching mechanisms.We discuss the resistive switching mechanisms of different materials in this paper and analyze the differences of those mechanisms from the view point of circuitry to establish their respective circuit models.Finally,simulations are presented.We give the prospect of using different materials in resistive RAM on account of their resistive switching mechanisms,which are applied to explain their resistive switchings.
文摘This study presents the deduction of time domain mathematical equations to simulate the curve of the charging process of a symmetrical electrochemical supercapacitor with activated carbon electrodes fed by a source of constant electric potential in time ε and the curve of the discharge process through two fixed resistors. The first resistor R<sub>Co</sub> is a control that aims to prevent sudden variations in the intensity of the electric current i<sub>1</sub>(t) present at the terminals of the electrochemical supercapacitor at the beginning of the charging process. The second resistor is the internal resistance R<sub>A</sub> of the ammeter used in the calculation of the intensity of the electric current i<sub>1</sub>(t) over time in the charging and discharging processes. The mathematical equations generated were based on a 2R(C + kU<sub>C</sub>(t)) electrical circuit model and allowed to simulate the effects of the potential-dependent capacitance (kU<sub>C</sub>(t)) on the charge and discharge curves and hence on the calculated values of the fixed capacitance C, the equivalent series resistance (ESR), the equivalent parallel resistance (EPR) and the electrical potential dependent capacitance index k.
文摘An earlier study manipulated the Butler-Volmer equation to effectively model a lithium-ion capacitor’s (LIC) energy storage as a function of its constituent components and charge current. However, this model had several shortcomings: computed temperature values were too low, voltage was inaccurate, and the model required Warburg impedance values that were two orders of magnitude higher than experimental results. This study began by analyzing the model’s temperature and voltage computations in order to justify output values. Ultimately, these justifications failed. Therefore, in situ temperature rise was measured during charge cycles. Experimental results indicated that temperature increases minimally during a charge cycle (<1%). At high current densities (≥150 A<span style="white-space:nowrap;">·</span>kg<sup>-1</sup>) temperature increase is negligible. After it was found that LIC temperature change is minimal during a charge cycle, the model accurately computed LIC voltage during the charge cycle and computed Warburg impedance that agreed with values derived from earlier experimental studies, even falling within the measurements’ precision error.
基金Supported by the National Key Research and Development Program of China under Grant No 2017YFA0204600the National Natural Science Foundation of China under Grant No 61404002the Science and Technology Project of Hunan Province under Grant No 2015JC3041
文摘An analytical model for current-voltage behavior of amorphous In-Ga-Zn-O thin-film transistors(a-IGZO TFTs)with dual-gate structures is developed.The unified expressions for synchronous and asynchronous operating modes are derived on the basis of channel charges,which are controlled by gate voltage.It is proven that the threshold voltage of asynchronous dual-gate IGZO TFTs is adjusted in proportion to the ratio of top insulating capacitance to the bottom insulating capacitance(C_(TI)/C_(BI)).Incorporating the proposed model with Verilog-A,a touch-sensing circuit using dual-gate structure is investigated by SPICE simulations.Comparison shows that the touch sensitivity is increased by the dual-gate IGZO TFT structure.
文摘This paper presents a numerical analysis for computation of free space capacitance of different arbitrarily shaped conducting bodies based on the finite element method with triangular subsection modeling. Evaluation of capacitance of different arbitrary shapes is important for the electrostatic analysis. Capacitance computation is an important step in the prediction of electrostatic discharge which causes electromagnetic interference. We specifically illustrated capacitance computation of electrostatic models like unit cube, rectangular plate, triangular plate, T-shaped plate, sphere and two touching spheres. Numerical data on the capacitance of conducting objects are presented. The results are compared with other available results in the literature. We used the COMSOL Multiphysics software for the simulation. The models are designed in three-dimensional form using electrostatic environment and can be applied to any spacecraft circuit modeling design. The findings of this study show that the finite element method is a more accurate method and can be applied to any circuit modeling design.