External Circuit Parameters Research Articles

The evaluation of electrical circuits for adjusting sound transmission properties of piezoelectric metamaterials

In rods and beams, piezoelectric patches with external circuits have been extensively studied to dampen structural vibrations at the sound source. This work uses a large flat-layer type of piezoelectric acoustic metamaterial (AM) model for noise attenuation in the sound transmission stage rather than at the sound source. This could be directly implemented as a large space sound transmission barrier at the interface of diverse media including gas, liquid, and solid materials. The general analytical model to derive acoustic properties of the piezoelectric acoustic metamaterial is established by the equivalent transfer matrix approach for normal incidence waves. This has been validated numerically using the finite element method and experimentally in the solid medium propagation for the first time. Moreover, a parametric study of sound transmission properties in air, water, and steel is conducted by adjusting external circuit parameters, flat-layer structures, and piezoelectric materials. The findings demonstrate the ability to control sound resonance frequency and bandwidth through the propagation process over a wide range using external circuit parameters alone. This endows the piezoelectric acoustic metamaterial with great versatility relative to conventional, fixed structure, metamaterials used as sound barriers at the interface of diverse media. In addition, the size of the piezoelectric AM can reach a deeply sub-wavelength level, less than 10−3 of the resonance wavelength in both water and solid media, which goes far beyond the wavelength-to-thickness ratio of classical acoustic metamaterials. The layer-type piezoelectric AM thus shows excellent performance in tunability and compactness for space-sensitive applications as well as great potential in combining metamaterials with electronic control.

Self-consistent integrated modeling of combined hybrid discharge-laser produced plasma devices for extreme ultraviolet metrology

Discharge- and laser-produced plasma (DLPP) devices are being used as light sources for extreme ultraviolet (EUV) generation. A key challenge for both, DPP and LPP, is achieving sufficient brightness to support the throughput requirements of nanometrology tools. To simulate the environment of a hybrid DLPP device and optimize the EUV output, we have developed an integrated HEIGHTS-DLPP computer simulation package. The package integrates simulation of two evolving plasmas (DPP and LPP) and includes modeling of a set of integrated self-consistent processes: external power source and plasma energy balance, plasma resistive magnetohydrodynamics, plasma heat conduction, detailed radiation transport (RT), and laser absorption and refraction. We simulated and optimized DLPP devices using Xe gas as a target material. We synchronized the external circuit parameters, chamber gas parameters, and laser beam temporal and spatial profiles to achieve maximum EUV output. The full 3D Monte Carlo scheme was integrated for detailed RT and EUV output calculations in Xe using more than 3600 spectral groups. The modeling results are in good agreement with Julich Forschungszentrum experimental data. Theoretical models, developed and integrated into the HEIGHTS package, showed wide capabilities and flexibility. The models and package can be used for optimization of the experimental parameters and settings, investigation of DLPP devices with complex design, analyzing the impact of integrated spatial effects and working timeline arrangement on the final EUV output, and EUV source size, shape, and angular distribution.

Simulation for pulse discharge performance of antiferroelectric capacitors

The discharge performance of antiferroelectric (AFE) capacitors is complicated and difficult to simulate due to the nonlinear polarization behavior of AFE. In this work, a nonlinear model for pulsed discharge AFEs was proposed based on a combination of the Preisach model and Kirchhoff’s law. The model was driven by the data from first-order reversal curves and direct-current-bias (DC-bias) dielectric test measurements. Thus, the discharge behavior of the AFE can be studied without actual discharge experiments. Specifically, AFE discharge waveforms were calculated and evaluated for different size parameters and external circuit parameters that were conducive to compare the properties of different AFE materials. Moreover, the size effect of the capacitor on the discharge performance was discussed, which should draw the attention of researchers to prevent exaggerated conclusions. As a consequence, this method would fill the gap of AFE discharge simulation.

A generalized external circuit model for electrostatic particle-in-cell simulations

A fully self-consistent second order accuracy model for coupling a generalized external circuit and a one-dimensional bounded electrode-driven plasma was proposed in this paper. The plasma was embedded in the circuit as a non-linear element with a potential difference. Based on Kirchhoff's voltage law and the definition of current, the problem of solving the generalized external circuit was transformed into an initial value problem of a set of first-order ordinary differential equations which can be discretized numerically by the second-order backward differential formula. The charge conservation equation at the electrode plate was coupled to the above equation, and the voltage, current, and surface charge density at the next moment were solved by a differential equation solver. Dirichlet boundary conditions of Poisson's equation were obtained through the surface charge density σ0 of the generalized external circuit equation and the plasma density ρ of the Particle-in-Cell (PIC) model. The spatial distribution of plasma potential was solved by using the second-order central difference scheme. The obtained potential at the electrode plate can be used as the Robin boundary condition of the system of generalized external circuit equations. In this model, the loose coupling between the generalized external circuit and plasma was realized by the boundary condition, and the system was fully self-consistent based on the charge conservation law and energy conservation law. We simulated the capacitively coupled plasmas (CCP) under different external circuits as the example and verified the performance of the model. This model can be used to study the influence of different external circuit structures and parameters on plasma discharge, and can be used for any plasma sources driven by electrodes, like CCP, some vacuum electronic devices, and Z-Pinches.

Magnetic Coupler Robust Optimization Design for Electric Vehicle Wireless Charger Based on Improved Simulated Annealing Algorithm

Fleets of autonomous vehicles including shuttle buses, freight trucks, and road sweepers will be deployed in the Olympic Village during Beijing 2022 Winter Olympics. This requires intelligent charging infrastructure based on wireless power transfer technology to be equipped. To increase the misalignment tolerance of a high-power wireless charger, the robustness of the magnetic coupler should be optimized. This paper presents a new type of unipolar coupler, which is composed of three connected coils in series. The dimensional configuration of the coils is analyzed by the finite element method. The characteristic parameters of the coil are identified with their influence on the self-inductance and coupling coefficient. An expert model is built, whose feasibility can be verified in the aimed design domain. Combined with the expert model, an improved simulated annealing algorithm with a backtracking mechanism is proposed. The primary coil can reach the expected characteristics from any starting parameter combination through the proposed optimization algorithm. Under the same conditions in terms of external circuit parameters, ferrite usage, and aluminum shielding, the offset sensitivity of the magnetic coupler can be reduced from 58.79% to 18.89%. A prototype is established, validating the feasibility of the proposed coil structure with the optimized parameter algorithm.

Plasma characteristics in Ne/Xe/HCl gas mixtures: A parametric study

An important class of exciplex molecules consists of rare gas halides (RgH) such as the monochloride of xenon (XeCl). This excimer emits photons with energies of about eV at wavelength of 308 nm. The present work examines the effects of external circuit parameters and total gas pressure on the characteristic properties of excimer discharge plasma in Ne/Xe/HCl gas mixture. The numerical investigation is carried using a zero-dimensional model, in which the electric circuit, the kinetic processes in the active medium, and the electron Boltzmann equation are considered. We find that increasing values of capacitance, inductance, charging voltage, and gas pressure affects significantly the discharge plasma behavior.

Electric Breakdown in Long Discharge Tubes at Low Pressure (Review)

The review is devoted to studies of the processes and mechanisms of ignition of a glow discharge in tubes whose length significantly exceeds their diameter (long discharge tubes) at low pressures (~10 Torr and lower) and moderate voltage rise rates (~1 kV/μs and lower). The electric field in such tubes before a breakdown is substantially nonuniform. Therefore, a breakdown occurs after an ionization wave (or waves) passes through the discharge gap at a speed of ~105–107 cm/s. This makes the characteristics of the breakdown in long tubes significantly different from the breakdown between large and closely spaced electrodes, where the electric field is uniform before the breakdown and where the Townsend or, under strong overvoltage, streamer mechanism is realized. On the other hand, the nature of these processes is very different from those occurring in nanosecond discharges, which arise at voltages with a steepness of ~1 kV/ns and higher and are associated with high-speed (~109 cm/s) ionization waves. The review is based on the materials of experimental and computational works published from 1938 to 2020. Breakdown processes, optical and electrical characteristics of the discharge gap during breakdown, and the influence of the external circuit parameters and external actions (shielding and illumination by external sources of visible radiation) are analyzed.

A New Approach to Model Reverse Recovery Process of a Thyristor for HVdc Circuit Breaker Testing

In the HVdc circuit breaker testing process, a thyristor is used to generate high current for the testing purpose. However, the reverse recovery process (RRP) of a thyristor can induce a significant overvoltage problem, which jeopardizes the reliable operation. It is important to model the RRP of a thyristor. The existing modeling methods usually omit the stray inductances in the circuit, which cannot describe the hard-switching process accurately. Therefore, this article proposes a novel method to model the RRP, considering the stray inductances. There are mainly three original contributions. First, the physical mechanism of the RRP is analyzed, describing the internal charge behavior and dividing the RRP into two stages. Second, this article provides a novel trigonometric exponential (TE) model of the thyristor voltage and current with analytical equations. Third, the extraction method of model parameters is also provided based on external circuit parameters and thyristor characteristics. In order to verify the proposed modeling method, a 1 kV/830 A IGBT-based circuit breaker is implemented with a thyristor to initialize the current. The experimental results show that the negative peak voltage induced by the RRP is as high as 4.26 kV, and the proposed TE model can precisely predict the overvoltage with a relative error of 7.51%.

Discharge properties of helicon oxygen plasma in the source and expansion chambers

In this paper, a study of a helicon discharge with O2 gas, operating at 13.56 MHz frequency and powers between 0–1500 W and pressure between 3 × 10−3 and 8 × 10−3 mbar is presented. Measurements of plasma parameters were made in the plasma production chamber as well as in the downstream expansion chamber. In the source chamber, transition from E to H and finally to W mode appears by increasing the input radio frequency (RF) power. To the best of our knowledge, this is the first detailed report of Helicon mode transition in Oxygen discharge. Mode transition is further confirmed by studying the radial density profile and by external matching circuit parameters measurement. Comparison of Langmuir probe I-V measurements and electron energy distribution function (EEDF) in source and expansion chambers confirms formation of negative ions. Negative ion fraction is measured in the expansion chamber by using two-probe method and densities of charged particles (electrons, positive and negative ions) are calculated using standard Langmuir probe theory and quasi-neutrality condition.

Research on Parallel Operation Characteristics and Current Sharing Method of High Power IGBT

With the development of power electronics technology, the capacity of power conversion devices is getting larger and larger, and the current level requirements for high-power IGBT are also getting higher and higher. A single device often cannot meet the requirements, and multiple IGBT need to be used in parallel. When IGBT is connected in parallel, due to the differences in device parameters, external circuit parameters and heat dissipation conditions, the current distribution is easily unbalanced, resulting in device performance waste or even damage. Therefore, the current sharing problem is the core problem to be solved in parallel connection of IGBT. In order to solve the problems such as difficulty in analyzing a single factor for coupling of various influencing factors, difficult control of temperature and high cost of circuit, this paper adopts Saber software simulation method to analyze the influence of various internal and external factors on IGBT’s dynamic and static current sharing, thus obtaining the relationship between these factors and corresponding countermeasures, and obtaining an effective IGBT parallel current sharing scheme. Finally, the correctness and effectiveness of this scheme are verified by experiments.

Possibility of tuning shunt circuits for multimodal damping of vibrations of structure with piezoelectric element

In this paper, an approach is proposed that allows for the selecting of the parameters of the shunt circuit that provide multimodal damping of vibrations for the corresponding piezoelectric element location. This technique is based on a solution to the natural vibration problem for an electroelastic structure with an attached piezoelectric element that is shunted with a single external resonant electric circuit. The solution to the problem is complex natural vibration frequencies. The analysis of their behaviour in the space of external circuit parameters (resistance – inductance) allows one to reveal the possibility of natural vibrations control at several frequencies (multimodal vibration damping). The applicability of the proposed approach is demonstrated using a shell structure in the form of a semi-cylinder with a piezoelectric element attached to its surface and shunted with a single-branched resonant electric circuit. Some options are considered that provide multimodal damping at several separated frequencies, which are not from the complete frequency range, and at all the frequencies, which are included in a specified frequency range.

Research on Current Transfer Characteristics of Hybrid Circuit Breaker in Low Voltage DC Micro-grid

The analysis of current transfer characteristics of hybrid DC circuit breakers is of great significance for improving their breaking capacity and implementing control strategies. This paper analyzes the principle of hybrid DC circuit breakers. The hybrid circuit breaker simulation model is built based on the Mayr arc model in Matlab/Simulink using IGBT, RCD snubber circuit and arrester model. The current simulation waveforms under different external circuit parameters and transfer branch parameters with a voltage of 400V and breaking fault current less than 200A are mainly studied. Through the analysis of the current transfer characteristics, a series of theoretically supported breaking characteristics are obtained, which provide a reasonable and effective reference for the fast and reliable breaking of DC micro-grid hybrid circuit breaker.

Development and characterization of a helicon plasma source.

The Helicon Plasma Source (HeliPS) designed and developed at the Centre of Plasma Physics-Institute for Plasma Research is a versatile helicon plasma device, which operates in a wide range of magnetic field configurations from 50 G to 500 G. This device is dedicated to perform a broad range of research activities. The main objective for development of the HeliPS is to carry out studies on ion-ion plasmas in electronegative gases. In the near future, ion-ion plasmas will be formed in electronegative gases in the downstream of the plasma production region. Although the system is primarily designed to carry out ion-ion plasma experiments, the same system can also be used for experimental studies on some basic helicon plasma properties such as wave propagation, wave coupling, and plasma instability. At present, argon plasma is produced with a RF power supply of 13.56 MHz frequency. External circuit parameters, such as antenna current, plasma resistance (Rp), and internal parameters, such as electron density and temperature, are measured. The details of the experimental setup development, device characteristic, as well as preliminary plasma production and characterization to confirm occurrence of the helicon plasma in the system are presented in this article.

An approach to determination of shunt circuits parameters for damping vibrations

ABSTRACTThis paper considers the problem of natural vibrations of a deformable structure containing elements made of piezomaterials. The piezoelectric elements are connected through electrodes to an external electric circuit, which consists of resistive, inductive and capacitive elements. Based on the solution of this problem, the parameters of external electric circuits are searched for to allow optimal passive control of the structural vibrations. The solution to the problem is complex natural vibration frequencies, the real part of which corresponds to the circular eigenfrequency of vibrations and the imaginary part corresponds to its damping rate (damping ratio). The analysis of behaviour of the imaginary parts of complex eigenfrequencies in the space of external circuit parameters allows one to damp given modes of structure vibrations. The effectiveness of the proposed approach is demonstrated using a cantilever-clamped plate and a shell structure in the form of a semi-cylinder connected to series resonant circuits.

Total Variation Diminishing technique in numerical simulation of Trichel corona in air

This paper deals with the numerical simulation of the Trichel pulse corona discharge in air under the room temperature and atmospheric pressure in the pin-plane configuration. A simplified drift-diffusion model of the discharge is considered with three species: electrons, positive and negative ions. The Total Variation Diminishing algorithm is used to stabilize the charge transport equations. The effect of the voltage level and the external circuit parameters on the average corona current, pulse frequency and pulse parameters are presented. The results of numerical predictions are compared with the experimental data.

A Variable Resistance Thyristor-Type Switch Modeling Technique

An accurate model for simulating the transient turn-ON performance of thyristor-type switches is desirable for the development of solid-state pulse generators. The existing thyristor models are not suitable since they are either impractical to implement in an SPICE simulator, do not accurately model transient turn-ON performance, or are dependent on external circuit parameters that may not be known during the design phase, such as the load and discharge capacitance. An empirical model is developed and presented for Silicon Power’s CCS SC 14N40 thyristor. The process of model determination is detailed, and waveforms obtained from the experiment and an SPICE circuit simulation that implements the thyristor model are discussed.

Suppression of self-pulsing regime of direct current driven microplasma discharges

An instability suppressor circuit for self-pulsing direct current (DC) driven microplasma discharge is proposed and experimentally tested over a range of pd values for helium feed gas. The external circuit configuration suppresses self-pulsing of the discharge, extending the normal glow regime to lower currents. The negative differential resistance (NDR) region was observed to shift further left in the voltage–current parametric space (i.e., lower current), and the slope of the NDR region was decreased substantially. In addition, the suppressor element decreased the pulsing frequency as well as the static positive resistance of the discharge in the shifted NDR region. Modeling of the discharge configuration indicated that the inductor element of the suppressor circuit increases the time lag of the plasma response, which increases the stable region of operation. A stability map in terms of the external circuit parameters is introduced.

Torsional wave propagation in a piezoelectric radial phononic crystals

A class of radial phononic crystals (RPC) is generated by periodically placing the piezoelectric material (PZT-4) on the base plate along the radial direction. Torsional vibration transmissibility inwards through an RPC’s plate is studied. Afterwards, the homogeneous material plate case is also computed for comparison. The obtained results are verified by finite element simulation. Both numerical results and finite element simulation results show that a single band is obtained in the piezoelectric RPC, but in the uniform base RESIN plate, the result shows that it forms a wide band which almost covers the whole frequency range. The effect of an external shunting circuit on the vibration band is studied as well. The results show that, in the low frequency range, the shunting resistance plays an important role in weakening this local resonant band. Investigating the influence of inner radius and span ratio of PRC’s plate on the wave band shows that varying the inner radius or the span ratio of PRC’s plate will affect the Bragg and local resonant band greatly. By setting structural parameters properly and controlling external circuit parameters effectively, the band becomes wider and attenuates faster. Hence, such band can be controlled reasonably. It is important in the torsional vibration control for composite structures consisting of shaft and gear.

Picosecond switching of high-voltage reverse-biased p +-n-n + structures to the conductive state by pulsed light

An analytical theory of high voltage reverse-biased p+-n-n+-structures picosecond switching into conducting state by pulsed lighting has been developed and a numerical simulation of this process has been performed. Combining the results of theory and simulation allowed us to obtain a simple relation between the parameters of structure, light pulse, external circuit and main characteristics of the process - the load current pulse amplitude and duration of switching process.

A compact repetitive high-voltage nanosecond pulse generator for the application of gas discharge

Uniform and stable discharge plasma requires very short duration pulses with fast rise times. A repetitive high-voltage nanosecond pulse generator for the application of gas discharge is presented in this paper. It is constructed with all solid-state components. Two-stage magnetic compression is used to generate a short duration pulse. Unlike in some reported studies, common commercial fast recovery diodes instead of a semiconductor opening switch (SOS) are used in our experiment that plays the role of SOS. The SOS-like effects of four different kinds of diodes are studied experimentally to optimize the output performance. It is found that the output pulse voltage is higher with a shorter reverse recovery time, and the rise time of pulse becomes faster when the falling time of reverse recovery current is shorter. The SOS-like effect of the diodes can be adjusted by changing the external circuit parameters. Through optimization the pulse generator can provide a pulsed voltage of 40 kV with a 40 ns duration, 10 ns rise time, and pulse repetition frequency of up to 5 kHz. Diffuse plasma can be formed in air at standard atmospheric pressure using the developed pulse generator. With a light weight and small packaging the pulse generator is suitable for gas discharge application.