Discharge Current Pulse Research Articles

Development and characteristics study of compact Penning ion source

A compact-size Penning ion source with a small discharge volume (1.24 cm3) is developed. It consists of two concentric cylinders of different heights that act as cathodes and one hollow cylindrical anode. A homogeneous magnetic field is achieved within the discharge volume with geometrical optimization of the ion source. As a result, dense plasma is generated at low discharge power. The dynamics of the pulse mode discharge at low pulse width and frequency of anode voltage are studied. A high discharge (hundreds of amperes) current pulse with low delay time and fast rise time is recorded. The ion source is equally efficient to operate in continuous as well as pulse modes of ionization for various gases. It is operated in a wide range of low pressure at low anode voltage. An extraction system is designed to extract ions efficiently in the axial direction at a variable extraction voltage. The beam current of 200 µA in continuous mode and 6 A fast pulse in the pulsed mode of discharge have been measured. Variable beam current can be extracted with variable extraction voltage for any potential application.

Realization of high discharge frequency in LC pulse generator for EDM by ignition using transistor circuit

Recent research has revealed that the LC pulse generator is able to generate higher rising speed discharge current pulses and high open voltage for EDM by utilizing electromotive force induced by an inductor. However, the discharge probability of LC generators is low because the duration of the open voltage pulse is significantly short in the order of several microseconds, although it usually takes several microseconds or longer for discharge to be ignited. In this paper, the discharge probability of the LC pulse generator was investigated, which was proved to be lower than 20% if the discharge frequency divided by the switching frequency of the LC generator is defined as the discharge probability of the LC generator. An excessively short delay time demonstrates that the gap will be short-circuited, resulting in decreased machining stability. Hence, this paper proposes a modified version of the LC generator, combining a high impedance transistor pulse generator with a conventional LC pulse generator. The high impedance transistor pulse generator is used to cause the ignition in the interelectrode gap, but not to supply energy to remove the workpiece. Triggered by the ignition, the LC pulse generator is activated to supply high discharge energies and unique discharge current shape. This modified LC pulse generator can produce a discharge frequency 2 to 3 times higher than the conventional LC pulse generator.

Pulsed thermo-induction-dynamic welding and pressing of dissimilar materials

To obtain permanent joints from diversified parts and powder compositions, it is proposed to use discharge-pulse processes with the accumulation of stored energy in a capacitor bank. Technological difficulties in the manufacture of structures from non-ferrous metal and alloy parts of different thicknesses are listed. The thermal effect is carried out by passing the discharge current from the batteries of pulse capacitors, and the power effect is realized through the use of an inductive-dynamic drive. A scheme for the series connection of a compacted powder with an induction-dynamic drive, consisting of a flat inductor with a pusher, is proposed. The physical essence of the formation of compounds is described. The processes responsible for the formation of permanent connections by a pulsed current discharge have been identified. A picture of the relationship between the main parameters of the pressing process – sintering in time, as well as the results of measuring the temperature of the sintering process of powders by the photoemission method is presented. The results of energy consumption for the consolidation of powder compositions with simultaneous welding to a steel base are given.

State-of-Charge and State-of-Health Joint Estimation of Lithium-Ion Battery Based on Iterative Unscented Kalman Particle Filtering Algorithm With Fused Rauch–Tung–Striebel Smoothing Structure

Abstract Traditional particle filtering has a large estimation error in the state of charge and Lithium-ion battery health of electric vehicle lithium batteries. For the above-mentioned problems, the lithium battery second-order resistance capacitance (RC) equivalent circuit model is established, and then, the model parameters are identified using the multi-innovation least square algorithm (MILS). Finally, an iterative unscented Kalman particle filtering algorithm with fused Rauch–Tung–Striebel Smoothing Structure (RTS-IUPF) applied to Li-ion battery state-of-charge (SOC) and state-of-health (SOH) joint estimation is proposed. The algorithm is based on the identification of battery parameters; the controller reads the sensor data and predicts the state results. RTS smoothing structure can do posterior estimation, and a significant probability density function is generated to select the optimal particle, and unscented Kalman algorithm regularized particles. The algorithm reduces the effect of the process noise covariance matrix and the measured noise covariance matrix on the filter accuracy and response time in traditional unselected Kalman filters. The algorithm proposed in the paper improves particle degradation and increases the estimation accuracy. Finally, the RTS-IUPF algorithm performs simulation analysis in Pulse current discharge condition and dynamic current condition (NEDC), respectively. The pulse current experimental results show that the mean absolute value error of UKF and particle filter (PF (number of particles N is 300)) is 1.26% and 1.24%, respectively, while the error of the RTS-IUPF is 0.748%. The root-mean-square error (RMSE) of the RTS-IUPF is reduced by 66.5% and 77.8% compared with UKF and PF. Furthermore, the error of joint estimation using this algorithm is smaller than that of single estimation. The RMSE of the RTS-IUPF joint is reduced by 27.4% compared with RTS-IUPF. The feasibility and effectiveness of the algorithm for the joint estimation of SOC and SOH of lithium batteries were verified.

PD Signal Detection Model Based on Multiscale Simulation of EM Generation and Transmission

Nowadays, the digital twin method has been gradually applied to power equipment condition monitoring. Since a main fundamental part of the digital twin is a simulation process with better fitting for the real one, this paper is devoted to building up a PD detection model to simulate the generation and transmission of electromagnetic (EM) wave signals caused by PDs, especially those inside the void defects. This model combines the micro discharge process with the transmission process inside certain geometry structures. Specifically, two commonly used methods are applied to simulate the processes correspondingly. The dielectric barrier discharge (DBD) model is used for the PD simulation inside void defects, while the finite-difference time-domain (FDTD) method is for the EM signal transmission process. The pulsed discharge current can be obtained during the simulation of DBD, which can function as the excitation source of the transmission process solved by FDTD. According to the PD detection model, the influences on the simulation results are discussed, including the impact on the discharge current caused by coefficient variation and the impact on the transmission process caused by the power equipment geometry structure and materials. As mentioned above, this paper is aimed at building a direct relationship between the observed EM signal and the micro discharge process, which reveals the physical process of PD signal measurement in virtual space that can provide more features for PD pattern recognition or noise elimination, and further the mechanism and theoretical analysis support for digital twin application.

Study on the effect of electric pulse treatment for disinfestation of vegetables

This paper describes a method of using pulsed discharge to control nematode diseases on tomato and cucumber rhizomes and crops grown in dacha plots. When pulsed discharges are applied to living tissue, certain chemical, physical, and biological processes occur, depending on the pulse energy, pulse discharge current, pulse discharge voltage, pulse discharge exposure time, pulse discharge impact current, and other similar factors. Electric pulses were applied to grafts of nematode-infested vegetables, tomatoes and cucumbers, to measure grafting ability. Crop yields were estimated by the total amount of produce grown on arable land, and the level of yield enhancement was determined by land sedimentation and proper placement of varieties and plant species. Proper selection of modern high-yielding varieties imported from Uzbekistan provides resistance to external adverse effects of nature and diseases. The creation of high-yielding varieties requires the discovery and cultivation of resistant hybrid varieties and the development and introduction of new progressive technological methods of plant cultivation. The objective of this study was to identify the main factors affecting the electric pulse discharge treatment of tomato and cucumber root crops infected with nematodes and their larvae. Various diseases occur in cotton, cereals, melons, vegetable crops, and indoors(greenhouses) on newly established farms in the Republic. Yields are particularly high in vegetable, melon, and greenhouse fields. In recent years, the impact of nematodes on plants has caused severe damage to crop yields. Treating crops with this formulation prevents nematode infestation of leaf veins. The economic damage caused by nematodes to agriculture is enormous. For example, in greenhouse vegetables (cucumbers and tomatoes) this indicator reaches 60% and in potatoes 80%. Therefore, the proposed method is realized in combination with an agrotechnical treatment process that is energy-saving, environmentally safe, and productive.

準定常作動2cm級自己誘起磁場型MPDスラスタの推力特性評価

In order to understand the characteristics of the Self-field MPD thruster with a discharge chamber diameter of 2cm, a ground experiment system was constructed and the thrust characteristics were obtained. For the power supply system, a capacitor bank using an electric double-layer capacitor and IGBTs was adopted, and it was confirmed that rectangular discharge current pulses could be output at arbitrary times. In the operation check of the experimental system, the discharge current, discharge voltage, and ion saturation current remained constant during 2ms, confirming the quasi-steady operation of the small MPD thruster for 2ms. Thrust measurement experiments were conducted using argon as the propellant, and a thrust force of 0.9N was confirmed at a maximum discharge current of 2.2kA. The measured thrust was proportional to the square of the discharge current. Therefore, it was confirmed that electromagnetic acceleration was dominant. As the highest propulsive characteristics, a specific impulse of 1800s and a propulsive efficiency of 2.3% were confirmed.

Li-NMC Battery Internal Resistance at Wide Range of Temperature Authors

One of the factors that affects energy transfer by Lithium-ion batteries is internal resistance. This internal resistance occurs due to resistivity of the electrochemical materials and its ionic component. Meanwhile, the internal resistance of a battery is affected by several factors such as temperature and their state of charge. To maintain battery health and prevent rapid degradation, the use of batteries at high temperatures should be avoided. In that relation, studies involving battery internal resistance are mostly conducted in an ideal temperatures range. This makes data on internal resistance at high temperatures scarce and insufficient. Accordingly, this internal resistance data is an important key component in predicting the battery temperature. Good internal resistance data at high temperatures can contribute to a more accurate battery temperature prediction. The purpose of this study is to provide internal resistance data for Li-MNC battery in wide range of temperature by means of experiment. In this study, the temperature of Lithium-ion Manganese-Nickel-Cobalt (Li-MNC) battery with the capacity of 40Ah was raised via high current discharge method. The discharge current used was 120A (3C) and 160A (4C). The discharge temperature was conducted from 26°C to 80°C. Internal resistance is then calculated from the measured voltage respond when 1C (40A) pulse current discharge flow through the battery. Results showed that as temperature increases, the value of internal resistance decreases. At the same time however, the rate of decrement declined until it become almost constant at high temperature range until reaching 80°C. The objective of this study is to provide the data of battery internal resistance at a wide temperature range up to 80°C. This information is important in developing a precise battery electro-thermal model that can predict battery performance and temperature. On the extend of that, this information will be useful in developing better battery management system to ensure good battery usage and safety.

Surface discharge characteristics of silicone gel and DBC under positive repetitive square voltage

• The surface discharge characteristics of silicone gel and DBC under positive square wave are different from AC and DC. • Surface discharge on the interface of silicone gel and DBC is a discharge phenomenon coexisting with single pulse and multiple pulses. • The discharge current pulse and displacement current can be separated. • The waveform parameters affect the initial voltage of surface discharge. Silicone gel and direct bonded copper (DBC) as the key components of high voltage power devices are widely used in the insulation packaging of high voltage power devices, respectively. With the increase of the voltage level, the insulation problem between silicone gel and DBC interface limits the development of high voltage power devices under positive square wave voltage. In this paper, an experimental platform under this voltage is established. The surface discharge characteristics of silicone gel and DBC interface are investigated. In order to remove the displacement current interference on the discharge current generated at the rising and falling stage of positive repetitive square voltage, high frequency discharge current and high-frequency magnetic field measured by antennas are simultaneously measured, and the discharge current pulse are extracted based on the one-to-one relationship between high frequency discharge current and high-frequency magnetic field. Furthermore, the specific characteristics of the forward and backward discharge current pulses of interface between silicone gel and DBC, such as amplitude, discharge number and partial discharge repetition rate, under different voltage amplitudes, frequencies and duty cycles are extracted and analyzed. Besides, the influences of frequency and duty cycle of the positive repetitive squarevoltage on the discharge initiation voltages are investigated. Finally, the mechanism of surface discharge between silicone gel and DBC under positive repetitive square wave voltage has been explained.

Performance gradient distribution of (Ti,W)C cermet by skin effects of high‐frequency spark plasma sintering

AbstractA (Ti,W)C cermet with graded properties was prepared using high‐frequency spark plasma sintering (HF‐SPS). The effects of the sintering process on the microstructure and mechanical properties of the prepared cermet material were studied, and the densification behavior of the material was analyzed using scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. Owing to the skin effect and pulse current discharge in HF‐SPS, the experimental results showed different sintering effects, as indicated by the current density difference between the surface layer and bulk. On one hand, the surface‐layer grains were larger, the metal phase was concentrated, and the hardness was high; however, the bulk grains were smaller, the metal phase was uniformly distributed, and the strength and toughness were high, causing the material to account for the higher hardness of the surface layer and the bulk strength and toughness. The skin effect of pulse direct current was key for the performance gradient distribution, whereas increases in the current density and sintering temperature decreased the skin effect. In general, the Joule heat effect was more significant, leading to abnormal grain growth.

Generation of High-Density Pulsed Gas–Liquid Discharge Plasma Using Floating Electrode Configuration at Atmospheric Pressure

In this paper, a high-density gas–liquid discharge plasma is obtained combined with nanosecond pulse voltage and a floating electrode. The discharge images, the waveforms of pulse voltage and discharge current, and the optical emission spectra are recorded. Gas temperature and electron density are calculated by the optical emission spectra of N2 (C3Πu → B3Πg) and the Stark broadening of Hα, respectively. The emission intensities of N2 (C3Πu → B3Πg), N2+ (B2Σ → X2Π), OH (A2Σ → X2Π), O (3p5P → 3s5S0), He (3d3D → 3p3P20), gas temperature, and electron density are acquired by optical emission spectra to discuss plasma characteristics varying with spatial distribution, discharge gap, and gas flow rate. The spatial distributions of discharge characteristics, including gas temperature, electron density, and emission intensities of N2 (C3Πu → B3Πg), N2+ (B2Σ → X2Π), OH (A2Σ → X2Π), O (3p5P → 3s5S0), and He (3d3D → 3p3P20), are presented. It is found that a high-density discharge plasma with the electron density of 2.2 × 1015 cm−3 and low gas temperature close to room temperature is generated. While setting the discharge gap distance at 10 mm, the discharge area over liquid surface has the largest diameter of 20 mm; under the same conditions, electron density is in the order of 1015 cm−3, and gas temperature is approximately 330 K. In addition, the discharge plasma characteristics are not kept consistent in the axial direction, in which the emission intensities of N2+ (B2Σ → X2Π), N2 (C3Πu → B3Πg), OH (A2Σ → X2Π), and gas temperature increased near the liquid surface. As the discharge gap is enlarged, the gas temperature increases, whereas the electron density remains almost constant. Moreover, as the gas flow rate was turned up, the electron density increased and the gas temperature was kept constant at 320 K.

Short pulse-enhanced vacuum arc evaporation

The paper studies a new method in vacuum-arc deposition technology that can be called short pulse-enhanced vacuum arc evaporation (s-PEVAE). This deposition technique combines sub-microsecond high-current pulsed and direct current operation of the arc-discharge source with the pulse frequency of several kilohertz. The high pulse voltage provides a high growth rate and amplitude of discharge current pulses, i.e., over 109 А/s and 1 kА, respectively. During the s-PEVAE process, the arc discharge power can achieve several hundreds of kilowatts. According to optical and probe measurements performed during the titanium evaporation in argon gas, ionization provided by s-PEVAE is higher than that provided by direct current vacuum arc evaporation (DCVAE). In s-PEVAE, the increase in the average discharge power is accompanied by the growth in the average density of the substrate ion current. At the same time, the deposition rate of the titanium coating decreases. All this leads to a significant change in the ratio between the ions bombarding the substrate and metal atoms forming the coating. Along with the substrate bias voltage, this ratio exerts a strong effect on the structure and properties of the deposited coating and can be controlled by the pulse parameters such as amplitude, time, and frequency.

SOC Estimation of E-Cell Combining BP Neural Network and EKF Algorithm

Power lithium battery is an important core component of electric vehicles (EV), which provides the main power and energy for EV. In order to improve the estimation accuracy of the state of charge (SOC) of the electric vehicle battery (E-cell), the extended Kalman filter (EKF) algorithm, and backpropagation neural network (BPNN) are used to build the SOC estimation model of the E-cell, and the self-learning characteristic of BP neural network is used to correct the error and track the SOC of the E-cell. The results show that the average error of SOC estimation of BP-EKF model is 0.347%, 0.0231%, and 0.0749%, respectively, under the three working conditions of constant current discharge, pulse discharge, and urban dynamometer driving schedule (UDDS). Under the influence of different initial value errors, the average estimation errors of BP-EKF model are 0.2218%, 0.0976%, and 0.5226%. After the noise interference is introduced, the average estimation errors of BP-EKF model under the three working conditions are 1.2143%, 0.2259%, and 0.5104%, respectively, which proves that the model has strong robustness and stability. Using the BP-EKF model to estimate and track the SOC of E-cell can provide data reference for vehicle battery management and is of great significance to improve the battery performance and energy utilization of EV.

Performance Estimation Method of Li-Ion Starting-Lighting-Ignition Batteries of Electric Vehicle through Lab-Scale Pouch Cell Experiment

CCA (cold-cranking amps) is used as one of the standards to define the power of a SLI (starting-lighting-ignition) battery of electric vehicles (EVs) by applying a large discharge current for a short time. It is easier to start an engine at a high temperature than a low temperature, so tests are usually conducted at a low temperature to meet the demands of users. However, in a large cell, the internal temperature of the cell rises due to the heat of the cell when a large current is applied. This phenomenon can increase the overall cell power performance because it has the effect of reducing ohmic overvoltage and improving electrode kinetics. Therefore, it is difficult to distinguish the effect of the temperature rise and applied current on the voltage curve during the consecutive pulse discharge.In this study, three times of 10 C discharge current pulse (~ 7 mA/cm2 in this study) is applied on a cell for 30 seconds, with rest periods of 600s, 30s included between each pulse. Evaluations were conducted from -18 ℃ to 50 ℃, with a LiFePO4/graphite lab-scale pouch cell rather than an actual large cell. Therefore, the temperature of the cell remained constant under the evaluation conditions in which heat generation is almost zero, so the voltage curves can be interpreted by excluding the effect of the temperature rise of a cell. Based on these experimental results, voltage curves were simulated depending on each internal resistance that related to Joule heating of the actual large cell. It is possible to predict the performance and degree of temperature rise of large cells. Also, this study proposes an effective and economical method to distinguish the effect of the temperature rise of the large cell and the applied current by using a lab-scale pouch cell with controlled temperature.

Investigation of the application of a high-voltage liquid voltage divider on Multisim software (version 10.0) and SolidWorks

The considered model was investigated according to the main characteristics corresponding to the real process (even the geometrical dimensions and electrophysical parameters coincide). It is known that a prerequisite for physical modeling is a strict geometric similarity of the model and character, as well as the equality of the corresponding similarity criteria in them. The cheapest insulator in the power industry is air. The air environment plays an important role in the design of ball arresters used in pulsed technology. In this case, it is important to measure the high-voltage voltage and obtain the exact shape of the discharge current pulse on the oscillogram. For this purpose, in this work, liquid voltage dividers were studied and the corresponding electronic models were developed. The results obtained in the electronic model are unreliable without experimental verification. The measuring equipment during the experiment gave positive results, indicating the quality of measurements, the correctness of the process of electric pulse treatment of seeds.

Arc energy minimization in high-power impulse magnetron sputtering

High-power impulse magnetron sputtering (HiPIMS) is rather a new and rapidly developing method for physical vapor deposition of thin films. Due to a high ionization degree of the sputtered material, the HiPIMS coatings have better properties than those produced by conventional DC magnetron sputtering (DCMS) and mid-frequency magnetron sputtering (MFMS). Along with its advantages, HiPIMS has some disadvantages, which make difficult its application. HiPIMS is characterized by the high pulsed discharge current, which provides higher arc frequency and energy than in MFMS and DCMS. This leads to larger defect size and quantity that appear in the coating obtained. This paper proposes the analytical simulation model to describe the discharge current and discharge voltage during arcing. This model helps to calculate the arc energy, lifetime, and maximum current. It also identifies what parameters of the power supply exert the highest effect on the arc parameters. The paper considers the types of the HiPIMS power supply and compares them with the view of arc quenching effectiveness. The model adequacy is verified by the experimental results of measurement the arc parameters in HiPIMS. It is shown the effect of arc energy on the size and number of defects in the carbon coatings obtained in HiPIMS.

Pressure broadening of 772.376 and 772.421 nm argon lines and kinetics of argon metastable atoms

Tunable diode laser absorption spectroscopy is used for recording the spectrally mixed profiles of argon 772.376 nm (2p7–1s5) and 772.421 nm (2p2–1s3) lines at different argon background pressures between 0.3 and 1 atmosphere. The absorbing atoms in the Ar*(1s5) and Ar*(1s3) metastable states are produced in a plane-to-plane dielectric barrier glow discharge operating at 20 kHz. The pressure broadening coefficient w and wavelength shift, s of the lines, deduced from the analysis of their variation versus pressure of recorded profiles, are w1=28.3 ± 2.0 pm (14.2 ± 1.0 GHz) and s1=11.5 ± 0.8 pm (-5.8 ± 0.4 GHz) for 772.376 nm line and w2=36.3 ± 0.5 pm (18.2 ± 0.3 GHz) and s2=12.8 ± 0.7 pm (-6.4 ± 0.4 GHz) for 772.4207 nm line, at 1 bar and 300 K. The progressive enhancement with argon pressure of the peak densities ratio [Ar*(1s3)]/[Ar*(1s5)], reaching 0.3 at 1 bar, reveals the importance of Ar-induced collisions for the population transfer from resonant 1s2 to the metasTable 1s3 state. Also, the time variation of Ar*(1 s) densities indicates the presence of a weak excitation channel outside the discharge current pulse initiated by the breakdown. This channel results from the heating of electrons by the electric field seen by the gas in the DBD gap.

Temperature dependency of diagnostic methods in lithium-ion batteries

Accurate estimation of battery performance and capacity is essential for assessing the capabilities of different batteries and determining state of health (SOH). Typically, diagnostic methods such as constant current charge/discharge, current interrupt, and electrochemical impedance spectroscopy (EIS) are demonstrated in laboratory tests with controlled environmental conditions. In real-world applications, such as electric vehicles, batteries are subjected to wide temperature ranges and temperature control for performance and SOH estimation is often not possible. This study investigates how battery diagnostic techniques are influenced by small temperature variations in order to determine suitable temperature windows over which different diagnostic methods can be performed without negatively influencing results. A lithium-ion 18650 cell is subjected to constant current charge, pulse discharge and EIS between 0 °C and 40 °C in 2 °C increments. The influence of variations in operating temperature on the diagnostic abilities of incremental capacity analysis (ICA), differential voltage analysis (DVA) and equivalent circuit fitting is explored. The findings of this study indicate that small temperature variations between diagnostic tests can lead to significant errors in the ability to diagnose degradation mechanisms, particularly at low temperatures (<10 °C). If temperature variations of ±4 °C or greater are expected between characterisation tests, then temperature regulation will be required to ensure accurate diagnostics. EIS based diagnostics was shown to be less temperature sensitive than voltage-based analysis techniques such as ICA.

Electrical Parameters of Nanosecond Dielectric Barrier Discharges (nsDBD)

In this study, an electrical device is proposed to generate plasmas in the nanosecond dielectric barrier discharge (nsDBD) configuration and to measure the electrical parameters of the discharge over a large bandwidth. Electrical parameters were experimentally determined using a common dielectric barrier discharge equivalent circuit extended here to high frequencies. An efficient synchronization procedure based on a comparison to circuit simulation results was proposed. Discharge current pulses with rise times less than 1 ns and amplitudes up to 50 A were measured. The energy deposited into the plasma and the discharge resistance were determined as a function of time. In addition, circuit simulations support the experimental approach. The nsDBD was accurately modeled by a resistance of the plasma channel following a Rompe and Weizel law in series with resistance for the discharge spreading along the dielectric surface and a sheath capacitance.

Registration of a pulsed generation of electron beam in the nanosecond range under heating and cooling cycles of a lithium niobate crystal at atmospheric pressure

We describe here an experimental prototype designed for registration of nanosecond discharge current pulses with an amplitude of up to 600 mA and a negative/positive polarity in the air gap between the +Z surface of a pyroelectric lithium niobate crystal and a flat copper electrode during the crystal heating/cooling cycles. The experiments were carried out in air at atmospheric pressure using a cylindrical lithium niobate sample with a diameter of 13 mm and a thickness of 7 mm. With the temperature varying from 20 to 80 °C, there were registered over 50 discharge pulses for heating as well as for cooling stage. Their parameters testify to pyroelectric generation of pulsed electron beam with a current at maximum from 45 mA to 600 mA, duration of about 15 ns, rise time from 1 to 1.9 ns, and transferred charge from 0.95 to 5.7 nC.