Discharge Circuit Research Articles

REGULATION OF OUTPUT DYNAMIC CHARACTERISTICS OF ELECTRIC DISCHARGE INSTALLATIONS WITH RESERVOIR CAPACITORS

The paper reveals the dependences of the output dynamic characteristics of semiconductor electric discharge installations (EDIs) with reservoir capacitors on the features of the change in the value of their capacitance. In particular, it is substantiated that for any fixed discharge duration less than the duration of reaching the maximum discharge current, an increase in the capacitance of such storage devices causes an increase in the value of the final discharge current both at aperiodic and oscillatory discharges in the linear resistance of the technological load. The change in the value of the discharge current in the load in the case of forced interruption of this current at a certain moment of time is investigated. Based on the obtained regularities, the authors of the work proposed to use the capacitance of the EDI's capacitor, which is larger than capacitance required to implement the maximum value of the discharge current in the load. Using a capacitor with a larger capacity and a fully controlled semiconductor switch in the discharge circuit of the EDI, it is possible to obtain the required maximum current value at a shorter duration of the discharge process. Thus, it is possible to regulate the main dynamic parameters of pulse currents in the load – the rate of their rise and/or their duration by changing the value of the capacitance of the discharge capacitor EDI. This approach is expedient for increasing the productivity of EDIs, focused on the production of dispersed spark powders of metals and alloys. References 15, figures 3.

A Study to Resist Conduced Interference from GIS Bus-Charging Currents Switching for Electronic Current Transformer

In this paper, we study the conducted interference to an electronic current transformer introduced in the process of bus-charging currents which are caused by switching a gas insulated switchgear (GIS) disconnector. To cope with these issues, the EMTP-ATP and Matlab/Simulink software are used to carry out equivalent modeling simulations and experimental research, respectively. More specifically, the very fast transient current generated by disconnector switching (DS) is used as the input source of the equivalent simulation model of the Rogowski coil, and the characteristics of conducted interference waveforms of the Rogowski coil, the active integrator and filter outputs under single and multiple breakdowns are analyzed step by step. Moreover, several anti-interference methods are proposed to improve the resistance to the high-voltage and high-frequency conducted interference for the Rogowski coil, such as reducing the Rogowski cut-off frequency, increasing the transient voltage suppressor (TVS), active filter, and Cy capacitor. Besides, the study also reveals that the residual charge of the integral capacitor will discharge with a time constant τ = 1 s after arc quenching with the first-order discharge circuit, which is composed of the feedback resistance and the integral capacitor C. Lastly, the experimental results demonstrate the correctness of the modeling method proposed in this paper and the effectiveness of anti-interference measures.

고반복 펄스 전원용 게이트 드라이버 회로 설계

In this paper, a new gate driver circuit is proposed to drive high voltage SiC MOSFET(Metal-Oxide-Semiconductor Field-Effect Transistor) of a solid-state pulsed power modulator. This gate driver circuit is designed to output pulses with repetition rates of several hundred kpps, and 1200V SiC MOSFETs are used as the main switch. In addition, a compact discharge structure was considered so that the volume of the modulator generating an average output of 10 kW could be designed to be within 26 liters, and thus a compact discharge structure based on an integrated gate driver of a discharge switch and a pull-down switch was implemented. In the experiment, synchronous stability was confirmed through gate synchronous driving tests of 12 discharge switches and pull-down switches, respectively. Based on this, a high repetition pulse output of 10 kV 150 kpps was finally performed, and the reliable operation of the proposed new gate driver and discharge circuit was verified.

Engineering Aspects and Parameter Evaluation of Ozone Generator

This paper introduces the Ozone generator parameters analysis and its engineering design aspects. Practically, Ozone is successfully used in water treatment applications; furthermore, it can be used to treat the secondary system cooling water in nuclear research reactors. The main element in this process is the Ozone generator; it has many parameters that need to be set at its design. These parameters can be divided into those related to the electrical equivalent circuit of corona dielectric barrier discharge (DBD), those associated with injected gas flow between the two electrodes, and those belonging to temperature of the electrodes. This paper is intended to those parameters that are related to the electrical equivalent circuit which has two standard models: linear and nonlinear. In this regard, the determination of the component values of nonlinear model can be achieved very hardly. To handle such determination, the nonlinear model can be approximately treated as a linear model in an approaching fashion. Based on this approximation, Lissajous plot and differential evolution (DE) methodologies are used for the computation of DBD ozone chamber parameters. Additionally, a new theoretical technique will be presented

Simplified High-Voltage Short-Pulse Power Modulator for DBD Plasma Application

Dielectric barrier discharge (DBD)-based plasma reactor and lamp are widely used for the growing areas of medical science, bacterial disinfection, pollution control, surface treatment, and so on. In this article, a simplified high-frequency, high-voltage short-pulse power modulator (HV-SPPM) is proposed for DBD plasma sources that are effectively capacitive loads. An energy discharge circuit (EDC) has been devised in the HV-SPPM to terminate the high-voltage pulses increase indefinitely for a capacitive load, which causes damage to the pulse power modulator. The HV-SPPM is using a wide bandgap (WBG) device without having a dissipative snubber circuit on primary side and magnetic compression circuit. The performance of the HV-SPPM has been validated experimentally by using a suitable DBD plasma-UV load. In the proposed HV-SPPM, a series diode with resistor has been introduced across the DBD plasma-UV lamp to damp out the sinusoidal oscillations between DBD capacitance and leakage inductance of the transformer. The HV-SPPM is capable to generate negative voltage pulses up to 6 kV and pulse width 800 ns with frequency variation up to 50 kHz. The proposed arrangement makes the HV-SPPM more compact, lightweight, simple, and highly efficient with very short rise and fall times voltage pulses suitable for the DBD plasma applications.

Control of Plasma Parameters by Hot Ionizing Electrons Using a Mesh Grid

In this article, we are reporting about the effect of energy and number density of hot primary electrons on plasma parameters in a new experimental configuration of a double plasma device. Here, we have controlled the plasma parameters in two plasma regions by a single discharge circuit. The discharge voltage is applied between hot filaments and a mesh grid. The energy of the hot primary electrons is increased by increasing the discharge voltage, and their number density is increased by increasing the filament heating voltage. It has been observed that the variations in plasma parameters are significant when the number density of primary electrons is increased.

Influence of an external circuit on the plasma parameters in the channel of the radio-frequency accelerator with a closed electron drift

The axial distribution of the plasma potential, concentration and temperature of electrons in an RF capacitive plasma source with the geometry of an accelerator with a closed electron drift is experimentally investigated in this work. Two cases of the external electrical discharge circuit are considered. In the first case, the electrodes were closed by direct current, in the second, they were opened. It is shown that direct current closure of the electrodes leads to a significant increase in the plasma potential and electron concentration. In a number of cases, local maxima of temperature and plasma density are observed near the electrodes, which can be associated with the occurrence of azimuthal electron drift in crossed electric and magnetic fields.

Influence of an external circuit on the plasma parameters in the channel of the radio-frequency accelerator with a closed electron drift

The axial distribution of the plasma potential, concentration and temperature of electrons in an RF capacitive plasma source with the geometry of an accelerator with a closed electron drift is experimentally investigated in this work. Two cases of the external electrical discharge circuit are considered. In the first case, the electrodes were closed by direct current, in the second, they were opened. It is shown that direct current closure of the electrodes leads to a significant increase in the plasma potential and electron concentration. In a number of cases, local maxima of temperature and plasma density are observed near the electrodes, which can be associated with the occurrence of azimuthal electron drift in crossed electric and magnetic fields.

Numerical simulation of gap length influence on energy deposition in spark discharge

The aim of the work is to study the influence of the length of the spark gap on energy input into the discharge channel during its gas-dynamic expansion. Methodology. The research is carried out by numerical modeling of the process of spark discharge development at variable values of the discharge gap length and at invariable other discharge conditions. The length of the gap was set in the range from 1 mm to 20 mm. The study was conducted using a numerical model of spark development, which takes into account the processes of nonstationary gas-dynamic expansion of the spark channel, the transient process in the electric circuit, nonequilibrium chemical processes, gas ionization, heat transfer and electrons thermal conductivity. The simulation was performed in atmospheric pressure nitrogen. The calculation was performed for various parameters of the RLC circuit, such as capacitance, inductance, resistance and voltage across the capacitor. Results. The study evaluates the influence of the spark length on the discharge current, the resistance of the spark channel, the energy deposited in the spark channel, and the distribution of thermodynamic parameters of the gas during the development of the spark discharge. It is confirmed that increasing the length of the gap increases the resistance of the spark. The deviation from the linear relationship between the deposited energy or the radiated energy and the length of the spark gap is estimated. Scientific novelty. A linear relationship between the gap length and the deposited energy is revealed when the total energy is above tens of Joules. Deviations from the linear dependence were detected in the discharge circuit when the total energy is below one of Joules. Practical value. The research results allow predicting the effect of the spark gap length on the energy input into the discharge channel under conditions of a slight change in the discharge current. In the conditions of essential change of amplitude of discharge current it is expedient to apply numerical researches for specification of changes in the energy deposited into a spark discharge.

Effects of Preparation Methods for Cu Foil on the Electric‐Explosion Properties

AbstractIn order to study the different structural characteristics and electric explosion properties of Cu foils prepared by different methods, Cu films were prepared by electron beam evaporation, electroplating, evaporation, and magnetron sputtering in this work. The morphology and structure of the Cu films were characterized by SEM, AFM, XRD. Furtherly, the Cu films were separately etched into a bridge foil shape to measure the explosion process of the Cu foil in the discharge circuit at the charging voltage of 3000 V, and the resistance and deposition energy were calculated. The results showed that the particle size and surface roughness of Cu foil prepared by evaporation was smallest, and the crystallization peak of Cu (111) texture was strongest. The surface roughness of the Cu foil prepared by magnetron sputtering was the largest, and the peak voltage was the highest of 1640 V. The Cu foil prepared by electroplating had the smallest initial resistance and the longest time to reach the peak resistance during the explosion process. The deposition energy of the Cu film is 93.37 mJ, which is the largest. Among these methods, the Cu foil prepared by electroplating is more conducive to energy conversion.

Pulse discharge characterization of perovskite dielectric ceramics

The pulse discharge characterization of perovskite dielectric ceramics, which has confronted a barrier between research and application, has the problems of inconsistent test standards and lack of comparability. To mitigate this issue and further advance the application process, we suggest an extrinsic standard (for convenience of comparison) for energy dielectric ceramics of thickness (0.2 mm), electrode area (4 mm2) and operation voltage (2 kV). We report the pulse discharge performance parameters of three typical dielectric materials: relaxor ferroelectric (Na0.5Bi0.5)0.9Li0.1Ti0.9Ta0.1O3 (NBLTT), paraelectric Ca0.6Sr0.4TiO3 (CST) and linear dielectric K0.5Na0.5NbO3 (KNN) glass ceramics through computer simulation and fitting of pulse discharge curves based on the resistance-inductance-capacitor pulse discharge circuit. The NBLTT ceramics exhibited higher peak current (16 A under 100 kV/cm) and stability with minimal variation less than 15% from 20 to 150 °C during pulse discharge compared with linear dielectric and ferroelectric glass ceramics. In addition, the NBLTT system holds the fast discharge time (90% of the discharge energy density released in about 100 ns) and good fatigue resistance. The short discharge time, high thermal stability and low medium voltage (500–5000 V) make the NBLTT ceramics promising for pulse capacitor in large current and low electric operation voltage conditions. An operable comparison standard and the research frontiers of pulsed dielectric materials are prospected.

EXPERIMENTAL AND NUMERICAL STUDIES OF PRESSURE AND GAP LENGTH EFFECTS ON ENERGY DEPOSITION IN SPARK DISCHARGE

A study of the influence of the discharge gap length and the initial gas pressure on the energy deposition into the discharge channel was done. The study was conducted at the same total discharge energy. It is experimentally shown that the connection of the voltage probe to the discharge circuit significantly affects the discharge current. The determination of the energy deposited into the spark channel is based on the results of numerical simulation of the spark channel development. Experimentally measured discharge currents at different pressures and the gap length were used as initial data for the calculation. Based on the obtained results, it is determined which of the factors (the initial pressure or the gap length) has the strongest influence on the energy input into the spark channel.

Adjustable current waveform via altering the damping coefficient: A new way to reduce Joule heating in electromagnetic forming coils

The temperature rise of the working coil due to Joule heating is a very important issue in electromagnetic forming processes. A technically simple and cost-effective method was proposed to address this problem, which only needs to introduce an additional resistor in the discharge circuit. The core of this method is to alter the current waveform during the forming process by adjusting the damping coefficient of the discharge circuit. The effectiveness of the method was numerically analyzed in detail and verified by the experimental investigations. It has been demonstrated that the Joule heating in the coil can be significantly reduced when a resistor was applied, while ensuring the forming depth of workpiece unchanged. As an example, more than 50 % of the Joule heating in a bobbin coil can be decreased when a resistor of 400 mΩ is applied. Meanwhile, the versatility of the developed method was further verified through the analysis of an electromagnetic forming system with a spiral coil and a high-frequency discharge. Furthermore, this work found that the line resistance of discharge circuit should not be as small as possible. It has been proved that when the line resistance is already small, further reducing it has little effect on the improvement of forming efficiency, but it will greatly increase the Joule heating in the coil. The developed method of achieving adjustable current waveform and its application in reducing the Joule heating of coil could be of great significance to the development of electromagnetic forming.

Conceptual design, manufacturing and investigation of dipole plasma ‎antenna with the capability of frequency variation in the VHF band

In this article, we simulate and manufacture a dipole plasma antenna whose frequency is variable in the VHF band. The conductive medium of antenna is the plasma created by the DC discharge in a glass tube. To excite the antenna, we use a cylindrical aluminum coupler installed at the middle of the antenna. By varying values of gas pressure, input impedance of circuit and the voltage deference between two ends of the plasma medium, one can change the working area of antenna at a few hundred gigahertz frequency interval. Simulation and numerical calculations are carried out for an antenna with 78cm length and 2cm radius at 0.8 bar pressure exerted under 15KV voltage difference. At constant pressure, by using some parallel resistors in the antenna circuit, the impedance of discharge circuit is changed and consequently the plasma density is varied. For plasma frequencies and , using semi-experimental formulae, analysis shows resonances at frequencies 250MHz and 311MHz, respectively, which are in good agreement with the experimental results which take place at frequencies 217MHz and 272MHz. Additionally, simulation is accomplished for a metal antenna with corresponding geometry whose working frequency detected at 184MHz.

Testing of dust clouds for the electrostatic-spark ignition hazard in industry. Need for a modified approach?

Current standard test methods for electric-spark minimum ignition energies (MIEs) of dust clouds in air require that a series inductance of at least 1–2 mH be included in the electric-spark discharge circuit. The reason is to prolong the spark discharge duration and thus minimize the spark energy required for ignition. However, when assessing the minimum electrostatic energy ½CU2 for dust cloud ignition by accidental electrostatic-spark discharges, current testing standards require that the series inductance of at least 1–2 mH be removed from the spark discharge circuit. No other changes of apparatus and test procedure are required. The present paper questions whether this simple approach is always adequate. The reason is that in practice in industry accidental electrostatic-spark discharge circuits may contain large ohmic resistances due to corrosion, poor electrical grounding connections, poorly electrically conducting construction materials etc. The result is increased spark discharge durations and reduced mechanical disturbance of the dust cloud by the blast wave emitted by the spark. Therefore, testing for minimum ½CU2 for ignition by accidental electrostatic spark discharges may not only require removal of the series inductance of 1–2 mH from the standard MIE spark discharge circuit. Additional tests may be needed with one or more quite large series resistances Rs inserted into the spark discharge circuit. The present paper proposes a modified standard test procedure for measurement of the minimum electrostatic-spark ignition energy of dust clouds that accounts for these effects.

ПРОЕКТУВАННЯ СИЛОВИХ ТРАНЗИСТОРНИХ ПЕРЕТВОРЮВАЧІВ ЕНЕРГІЇ ДЛЯ СИСТЕМ АВТОМАТИЗОВАНОГО ЕЛЕКТРОПРИВОДУ ПОСТІЙНОГО СТРУМУ

Purpose. One of the integral parts of modern mechatronic motion modules, where electric motors provide the conversion of electrical energy into useful mechanical action, are power semiconductor converters. At the current stage of industrial development, the use of energy converters as a part of a fully controlled semiconductor switches opens wide opportunities for the development and implementation of highly efficient resource- and energy-saving devices. Methodology. Two types of converters are widely used in automated DC electric drive systems: controlled thyristor rectifiers and pulse-width DC converters, the principle of operation of which is based on the key mode of operation of the regulating semiconductor, which periodically connects the source voltage to the output circuit. The paper presents a laboratory sample of a power semiconductor DC energy converter, which can ensure reliable motor operation in both motor and braking modes. Results. The presented transistor energy converter consists of two main parts: the first part performs the main role – control, and it includes a control unit, a microcontroller, and a device for displaying current information. The second part is a power module, which includes the necessary power supply modules, control drivers and power transistor switches of the converter. To obtain high quality transients of the electric drive system, the circuit is equipped with additional sensors of current, voltage and speed, which takes part in the formation of the control signal and in the protection systems against overvoltage and current jumps. Practical value. The paper substantiates the parameters of the components and proposes developed technical solutions for the construction of a microprocessor control system for a transistor DC energy converter. It is shown that in order to ensure a constant generator mode in automated electric drive systems, where the primary energy converter is an uncontrolled rectifier, it is expedient to install an energy discharge circuit in the DC link. References 18, figures 14.

ВЛИЯНИЕ ИМПУЛЬСНОГО МАГНИТНОГО ПОЛЯ ВЫСОКОЙ НАПРЯЖЕННОСТИ НА ПОКАЗАТЕЛИ АНТИАГРЕГАЦИОННОЙ АКТИВНОСТИ ХИМИЧЕСКОЙ СУБСТАНЦИИ И ГОТОВОГО АПТЕЧНОГО ПРЕПАРАТА ПЕНТОКСИФИЛЛИНА

It was found that the pharmaceutical preparation of pentoxifylline, treated with a pulsed magnetic field (PMF), changes the antiaggregatory properties.The pharmaceutical preparation contains the pure substance of pentoxifylline and a number of excipients. To understand the mechanism of changes in the antiaggregatory activity of a pharmaceutical preparation, the goal was to further investigate the effect of PMF parameters on its chemically pure substance.PMF processing was carried out on the «MIU Bio» installation with a single exposure at a field strength in the range (0.48–1.17) 106 A/m at discharge circuit frequencies (8–50) 103 Hz.Experiments have shown that the effect of PMF on the pure substance of pentoxifylline did not cause significant changes in its antiaggregatory activity. This result made it possible to get one step closer to understanding the mechanism of the effect of PMF on a given drug. Apparently, the reason for the change in the biological effectiveness of the pharmaceutical pentoxifylline treated with PMF lies in the effect of impurities, which will be the focus of further research.

Robust Control of Winding-Based DC-Bus Capacitor Discharge for PMSM Drives in Electric Vehicles

Active discharge circuit is of great significance for discharging the dc-bus capacitor voltage to safe voltage in the electric vehicles (EVs) based PMSM drive system when EVs encounter an emergency such as a crash event. However, when electric vehicle occurs a collision, the active discharge circuit may be damaged or failed, which poses a great electric threat to the passengers and succors. In order to resolve the problem, this article proposes a winding-based dc-bus capacitor discharge method. To quickly discharge the dc-bus capacitor energy, the machine windings are used as discharge resistance with active discharge circuit fault. For the purpose of reducing the bus voltage to safe voltage as soon as possible, the discharge method can be divided into two phases, rapid discharge stage and bus voltage regulation stage. Firstly, the dc-bus voltage will be dropped to safe voltage due to the large flux-weakening current applied to the d-axis. Secondly, in order to stabilize the bus voltage at safe voltage, an extended observer state (ESO) is designed to estimate and compensate the total power loss that is regarded as disturbance in bus voltage regulation stage. The parameters of the proposed ESO are designed and the tracking performance is analyzed. Finally, the proposed discharge technique is validated by both simulation and experiments, which are conducted on a three-phase SPMSM drive platform.

Investigation of the effect of electro-hydraulic pulses on the combustion process of phosphorus sludge

The article considers the influence of electro-hydraulic pulses on the combustion of phosphorus sludge. Electric discharges in the environment of phosphorus sludge are sources of shock waves, which destroying the structure of phosphorus sludge and contribute to the intensification of the combustion process. A distinctive feature of the electro-hydraulic effect is the ability to control the parameters of pressure waves over a fairly wide range using the characteristics of the electric discharge circuit. For determine the optimal productivity and purity of the final product of the electric discharge unit’s operation mode, experiments were conducted on the effect of the discharge energy on the efficiency of the electric discharge method for extracting phosphorus from phosphorus sludge. The efficiency of the electric discharge process was estimated by the amount of phosphorus that was released after settling and expressed as a percentage of the total amount of phosphorus in a phosphorus sludge’s portion. The experiments were conducted out for sludges of different structures, with different phosphorus content and were conditionally divided into three groups: “rich” with phosphorus content — 70 %, “medium” — 50 % and “poor” — phosphorus content — 30 %.

Optimization of discharge circuit model based on electro pulse boring experiment

High-voltage electro pulse rock-breaking is a green breaking technology, which can achieve high efficiency of rock-breaking. It has a wide application prospect in deep and ultra-deep well drilling and tunnel driving in the future. Pursuant to the time delay characteristics of the gas discharge switch in the electro pulse boring (EPB) system, the equivalent model of the discharge circuit is established based on the time-varying resistance model. With this model, the real-time parameters such as voltage, current and discharge energy can be predicted in the EPB process of different rocks. In line with the arrangement of coaxial cylindrical electrodes, a 25 mm electrode drill bit is designed, and an EPB experiment system is developed based on the transformer step-up pulse power supply. The electro pulse breaking of red sandstone, yellow sandstone, concrete and granite, and the complete drilling of 60 mm diameter in red sandstone and concrete are realized, and EPB rules of different rocks are obtained. The real-time curves of electrical parameters in different rocks are collected by electrical parameter tester. The model parameters are identified based on the least square method of unconstrained nonlinear optimization. The current curve fitted by the identification parameters and the current curve obtained from the experiment are featured in high coincidence and good follow-up, which proves the accuracy of the optimized model and parameter identification. The optimization of the discharge circuit model and the identification of the model parameters based on EPB experiment are of great significance to guide the selection of the technological parameters of EPB, improve the efficiency of rock-breaking and reduce the energy loss in the drilling process.