Pulsed Power Supply Research Articles

Fabrication of Die Sink Electrochemical Machining Tools Using Low Melting Fusible Alloy and Polymer Based Additive Manufacturing

The present work introduces a novel approach to fabricating die-sink tools for electrochemical machining (ECM) using low-melting fusible alloy and additive manufacturing. Three methods are proposed, each bettering the previous in manufacturing sustainability. The versatility of the process enables the fabrication of die-sink ECM tools that are hitherto considered challenging to fabricate. Finite element analysis was used to simulate the temperature rise of the low-melting (50 °C) tool due to Joule heating, accounting for electrolyte flow under various process parameters. A novel validation method employed a thermostat temperature probe as a cathode. Experiments based on the simulation data revealed that for a 4 mm tool diameter, the tool is unlikely to melt at 3 A current, 200 μm inter-electrode gap, 11.97 S m−1 electrolyte conductivity, and 1.7 m s−1 electrolyte velocity. A pulsed power supply was subsequently used to improve heat dissipation, and ECM was successfully carried out using tools of various shapes, demonstrating the effectiveness of the developed fabrication methods.

Effects of ultrasonic treatment and current pulse frequency on properties of micro-arc oxidation coating on Mg alloy LAZ931

To enhance corrosion resistance of magnesium-lithium (Mg-Li) alloy LAZ931 in corrosive environments, a micro-arc oxidation (MAO) based surface treatment was carried out under a unipolar pulsed power supply. Effects of ultrasonic treatment and current pulse frequency on the performance of MAO coatings were investigated using scanning electron microscopy, electrochemical characterization, and friction wear tests. Results demonstrate that ultrasonic treatment greatly reduced the number density of micro-defects in the resulting MAO coatings and improved their overall performance. Corrosion and wear resistance of the MAO coating increased when current pulse frequency increased from 400 to 2000 Hz. Those findings are beneficial for improving the performance of MAO on Mg-Li alloys through optimizing the processing parameters.

A Multi-Module HTS Inductive Pulse Power Supply With Wide Current Pulse Output

A Multi-Module HTS Inductive Pulse Power Supply With Wide Current Pulse Output

Development of an inductive energy storage pulsed power supply using SiC semiconductor devices for ozone production by streamer discharges

An inductive energy storage (IES) pulsed power generator driven by a silicon carbide metal oxide semiconductor field effect transistor (SiC-MOSFET) with a blocking voltage of 1.2 kV was developed. The IES pulsed power generator consists of a capacitor, a pulsed transformer and the SiC-MOSFET used as an opening switch. The influence of the turn ratio of the pulsed transformer on the output voltage was evaluated. The output voltage amplitude increased with increasing secondary turn ratio. Under the conditions of no load, a peak output voltage of 13 kV and a pulse width of 120 ns were obtained with a voltage across the drain–source terminals of the MOSFET of 1 kV. The peak voltage increased, and the peak current and pulse width decreased, with increasing load resistance and decreased capacitance. The maximum energy transfer efficiency was obtained at 500 Ω and was approximately 56%.

A Novel Modular Cascaded H-Bridge High-Power Accelerator Dipole Magnet Pulse Power Supply for HIRFL-CSRm

A Novel Modular Cascaded H-Bridge High-Power Accelerator Dipole Magnet Pulse Power Supply for HIRFL-CSRm

Analysis of discharge parameters of an argon cold atmospheric pressure plasma jet and its impact on surface characteristics of White Grapes

An argon cold atmospheric-pressure plasma (CAP) jet operated using bipolar pulsed power supply has been characterised electro-optically and the discharge parameters are optimized. An analysis has been done on the impact of the argon CAP jet treatment on the surface properties of white grapes for different treatment time period. The developed argon CAP jet is a plasma source based on dielectric barrier discharge (DBD) that has been tuned at various input parameters including applied voltage, frequency, average power consumption, and argon flow rate. Optical Emission Spectroscopy (OES) is used to identify the generated species along with plasma parameters. The collisional–radiative (CR) model is employed to extract the electron density (ne) and electron temperature (Te) from the spectra at the optimised applied voltage of 4 kV, frequency 20 kHz and argon flow rate of 4 slpm. The OES results coupled with the CR model (ne ∼ 1014 cm−3 and Te ∼ 1 eV) and the plasma gas temperature measurement through OH (A-X) transitions (Tg ∼ 310.5 K) show the non-equilibrium nature of the argon CAP jet. A comparative analysis between untreated and treated white grapes reveals that the argon CAP jet treatment influences surface microstructure, increasing hydrophilicity (with a ∼49.3% decrease in water contact angle) along with slight changes in surface temperature (∼5 °C increase), colour (ΔE* < 1.5), and physiochemical properties such as chemical composition (no change) and Total Soluble Solid (TSS) content (∼8.3%). It is inferred that this type of CAP jet treatment of white grapes only affects the physical characteristics of the grape surface and does not alter any chemical compositions.

Ozone production in nanosecond pulsed dielectric barrier discharge in synthetic air: the Effect of Pulse Width

This work investigates the effect of pulse width on the characteristics of electrical discharge, optical emission spectra and ozone production in a water electrode DBD using a modulable nanosecond pulsed power supply. Results show that the increase of pulse width tpw slightly increases the spectral intensity and the rotational temperature Trot, with a typical Trot of 299 ± 5 K at an applied peak voltage Vp of 18.6 kV and a tpw of 400 ns. The electronic excitation temperature Texc increases linearly with Vp and gradually with tpw, while the electron density ne shows a non-linear relationship with tpw. Results also show that an increase in tpw slightly increases the energy density. At low energy densities (SIE < 50 J/L), increasing tpw can improve ozone generation efficiency, reaching a maximum of 99.64 ± 0.87 g/kWh at 33.60 ± 1.53 J/L at a tpw of 900 ns. This investigation provides substantial insight into the nanosecond pulsed ozone production.

Enhancing energy storage performance of dielectric capacitors: Tailoring CaO-SrO-Na2O-Nb2O5-SiO2 glass-ceramics through controlled crystallization for pulse power applications

As potential dielectric materials for capacitors, glass-ceramics exhibit significant promise in the realm of pulse power supply. Extensive research has been undertaken to explore the commendable voltage resistance and favorable dielectric properties of glass-ceramics. They exhibit a rapid charge and discharge rate. However, the limited energy storage density of glass-ceramics constrains their practical application. In this study, we focused on the preparation of CaO-SrO-Na2O-Nb2O5-SiO2(CSNNS) glass-ceramics through conventional melting and high-temperature crystallization processes. Our investigation delved into the impact of crystallization temperature on the phase composition, dielectric properties, and energy storage characteristics of the CSNNS glass-ceramics. The results indicate a direct correlation between the dielectric constant and dielectric loss, both exhibiting an upward trend with increasing crystallization temperature. Simultaneously, the microstructure of the glass-ceramics manifests signs of deterioration, characterized by larger grain size and heightened porosity, leading to a reduction in breakdown strength. At a crystallization temperature of 1100 °C, the CSNNS glass-ceramics demonstrated a remarkable combination of a high dielectric constant (∼280) and superior breakdown strength (481 kV/cm). The achieved maximum theoretical energy storage density reached 2.87 J/cm3. At an electric field of 100 kV/cm, the effective energy storage density is 0.23 J/cm3, and the energy storage efficiency is 72 %. These findings demonstrate the broad application potential of the CSNNS glass-ceramics in the domain of pulse power, highlighting their relevance for future developments in this field.

Pulse power supply for plasma aerodynamic actuators

The reduction of local heat load on the structural elements of aircraft or spacecraft vehicles due to the shock wave/boundary layer interaction can be successfully controlled in the future using a system of plasma actuators. The efficiency of plasma aerodynamic actuators operation is directly related to a power source. It determines a covered plasma area, an air flow speed and a thrust the actuator creates. The paper deals with the operation of a high-voltage source of sawtooth pulses with high efficiency for controlling plasma actuators. The pulse power source can be easily scaled for different nonlinear capacitive loads.

Enhanced energy storage performance of Bi(Mg0.5Hf0.5)O3 modified K0.5Na0.5NbO3 relaxor ferroelectric ceramics via synergistic strategy

K0.5Na0.5NbO3 (KNN)-based ceramics with large polarization (Pmax) and submicron grain size are considered as promising candidates for dielectric capacitors. However, the existence of significant remnant polarization (Pr) imposes constraints on achieving high recoverable energy storage density (Wrec) and efficiency (η). In this study, we developed and produced ceramic materials by utilizing the composition of (1-x)K0.5Na0.5NbO3-xBi(Mg0.5Hf0.5)O3 ((1-x)KNN-xBMH, x = 0–0.22), employing a viscous polymer rolling technique. We utilized a combined strategy to improve the energy storage capabilities of these materials by manipulating their crystal structures, inducing relaxor behavior, and minimizing microdefects. As a result, we obtained an optimum Wrec of 3.32 J/cm3 and η of 85.37 % at an electric field strength of 350 kV/cm in the x = 0.18 ceramic. Furthermore, excellent temperature stability was observed within the temperature range 20–120 °C, along with frequency stability across frequencies between 5 and 500 Hz. Moreover, at 200 kV/cm in the same composition (i.e., 0.82KNN-0.18BMH), we obtained a power density value as high as 103.13 MW/cm3, accompanied by a fast discharge speed reaching 30.6 ns. Overall, our results demonstrate that the comprehensive energy storage performances exhibited by the 0.82KNN-0.18BMH ceramic make it highly promising for applications in pulsed-power supply.

Ammonia pyrolysis oxidation excited by nanosecond pulsed discharge: Global/fluid models hybrid solution

The kinetic characteristics of plasma-assisted oxidative pyrolysis of ammonia are studied by using the global/fluid models hybrid solution method. Firstly, the stable products of plasma-assisted oxidative pyrolysis of ammonia are measured. The results show that the consumption of NH3/O2 and the production of N2/H2 change linearly with the increase of voltage, which indicates the decoupling of non-equilibrium molecular excitation and oxidative pyrolysis of ammonia at low temperatures. Secondly, the detailed reaction kinetics mechanism of ammonia oxidative pyrolysis stimulated by a nanosecond pulse voltage at low pressure and room temperature is established. Based on the reaction path analysis, the simplified mechanism is obtained. The detailed and simplified mechanism simulation results are compared with experimental data to verify the accuracy of the simplified mechanism. Finally, based on the simplified mechanism, the fluid model of ammonia oxidative pyrolysis stimulated by the nanosecond pulse plasma is established to study the pre-sheath/sheath behavior and the resultant consumption and formation of key species. The results show that the generation, development, and propagation of the pre-sheath have a great influence on the formation and consumption of species. The consumption of NH3 by the cathode pre-sheath is greater than that by the anode pre-sheath, but the opposite is true for OH and O(1S). However, within the sheath, almost all reactions do not occur. Further, by changing the parameters of nanosecond pulse power supply voltage, it is found that the electron number density, electron current density, and applied peak voltages are not the direct reasons for the structural changes of the sheath and pre-sheath. Furthermore, the discharge interval has little effect on the sheath structure and gas mixture breakdown. The research results of this paper not only help to understand the kinetic promotion of non-equilibrium excitation in the process of oxidative pyrolysis but also help to explore the influence of transport and chemical reaction kinetics on the oxidative pyrolysis of ammonia.

Investigating the principle and application of high-frequency and high-voltage pulse AC equipment for oil–water separation of heavy crude oil

To address the challenges of oil–water separation encountered during the processing of heavy crude oil, this study meticulously examines the kinetics of demulsification under an electric field. Consequently, a cutting-edge high-frequency/high-voltage AC pulsed power supply has been innovatively developed. This device boasts a flexible voltage-adjustment mechanism, strategically enhancing the inverter output voltage incrementally throughout the pulse’s duration. This method effectively reduces the negative impact of current surges on the operational stability of crude oil desalination plants, especially during the commutation periods of the switching devices. Furthermore, it resolves the issue of premature power supply shutdowns to the desalination plant, caused by peak currents misinterpreted as critical short-circuit currents leading to pole plate breakdowns. An industrial application study conducted at Shandong Chambroad Petrochemicals Co., Ltd. Under identical operational conditions, the power supply designed in this research outperforms traditional electrical desalting transformers in several key aspects. These include a notably enhanced oil–water separation capability and significantly more stable performance. Remarkably, the desalting efficiency shows substantial improvement even at increased feed rates, under constant other conditions. The experimental findings indicate that the average rates of desalination and dehydration achieved by this power supply exceed 90%. Moreover, even when the feed rate is augmented by approximately 75% under constant operating conditions, the desalination efficiency remains 78.49% higher than that achieved by standard industrial frequency electric desalination transformers. Additionally, the desalting outcomes are predominantly unaffected by fluctuations in the initial salt content of the feedstock, demonstrating the robustness of the developed solution.

Predicting the impact depolarization behavior of PZT-5H based on machine learning

In order to establish the relationship between the load and depolarized charge under stress waves, we established the stress depolarization experimental platform and obtained the time history curve of charge variation with the load. Then, we built a theoretical model of PZT-5H impact depolarization and physically described the model based on the characteristics of the experimental data and domain switching. Meanwhile, we obtained the uncertain parameters in the model by using the CBP neural network and the genetic algorithm. Finally, the effectiveness of the impact depolarization theory model was verified by comparing it with experimental values. The results indicated that the established PZT impact depolarization model can reflect the depolarization law of materials in the range of 0 ∼ 250 MPa stress waves. It provided a predictive method for the application of piezoelectric materials in extreme engineering such as contact fuses, pulse power supplies, and impact sensors.

Reliability of DC-link capacitor in pulsed power supply for accelerator magnet

Reliability of DC-link capacitor in pulsed power supply for accelerator magnet

Design and development of FPGA based trigger system for automation of metallic tokamak (MT-I)

A field-programmable gate array (FPGA)-based trigger system (FTS) is designed and developed to replace the existing microcontroller-based system for the automation of metallic tokamak (MT-I). MT-I consists of three main systems: MT-I vacuum vessel and gas filling system, a pulsed power supply system, an electronic system based on diagnostics and data acquisition (DAQ) systems. The power supply system provides pulsed power input to the central solenoid (CS), poloidal field coils (PF), toroidal field coils (TF), and microwave systems using thyristors and insulated-gate bipolar transistors (IGBTs). The (DAQ) system acquires experimental data from MT-I diagnostics using national instruments (NI) DAQ cards. A concurrent processing system is required to incorporate time delay in the triggering process of central solenoid (CS), poloidal field coils (PF), toroidal field coils (TF), microwave source and DAQ systems. Therefore, an FTS is designed and developed to complement the processing capability, unlike a microcontroller. The FTS has twenty concurrent triggering channels, adjustable from time reference zero, and control from a simple graphical user interface (GUI) designed on LabVIEW. For current buffering and optical isolation against high voltages in the MT-I power supply system, a peripheral electronic system (PES) and field trigger modules (FTM) have been developed as part of FTS. The designed and developed FTS was tested successfully on MT-I.

Synergistic demulsification of oil-in-water emulsion using bidirectional pulse electric field and fiber coalescence

The methods of demulsification using bidirectional pulsed electric field (BPEF) and fiber coalescence exhibit limited effectiveness under conditions of high emulsification degree of oil-in-water (O/W) mixture or low oil content. However, there is an urgent requirement for efficient O/W emulsion separation. This study investigated the synergistic demulsification of oil-in-water emulsion using BPEF combined with fiber coalescence. It explored the impact of coalesced fiber parameters, output parameters of bidirectional pulse power supply, and water quality parameters on the demulsification performance of O/W emulsion. The demulsification performance of BPEF coupled with viscose fiber was superior to that of coupling polytetrafluoroethylene (PTFE) fiber, and the 10 % fiber filling rate exhibited a better synergistic demulsification effect than the 5 % fiber filling rate. The optimal synergistic demulsification performance was achieved with a 10 % viscose fiber filling ratio, 400 V pulse voltage, 50 Hz frequency and 30 % duty ratio. The O/W emulsion with an oil content of 4100 mg/L could be reduced to 9.28 mg/L, resulting in a demulsification efficiency of 99.77 %, which was 55.98 % higher than that of BPEF. The study showed that utilizing BPEF in conjunction with fiber coalescence could be a promising approach for synergistic demulsification of O/W emulsions.

Coordinate Sizing and Control of the Onboard Pulse Power Supply System

Coordinate Sizing and Control of the Onboard Pulse Power Supply System

Nanosecond pulsed gliding arc plasma for ammonia synthesis: better insight from discharge mode and vibrational temperature

Low-temperature plasma technology is a promising technological route to achieve green and efficient ammonia synthesis at ambient temperature and pressure. In this work, a Laval nozzle type gliding arc plasma reactor was designed for the direct synthesis of ammonia from N2 and H2 discharges ignited by a high voltage nanosecond pulsed power supply to investigate the effect of different electrode gaps, pulse voltages, and V N2:V H2 on ammonia synthesis. The nanosecond pulsed plasma discharges were characterized through oscilloscope and optical emission spectroscopy (OES). The maximum rate of NH3 synthesis was 538.12 μmol·h−1 at 1.5 mm electrode gap, 16 kV peak pulse voltage, 6 kHz pulse repetition frequency, 100 ns pulse width, 100 ns pulse rising edge, 100 ns pulse falling edge, and 200 mL·min−1 total gas flow rate with V N2:V H2 = 1:1. It was demonstrated that the discharge mode of the nanosecond pulsed gliding arc plasma can transit from a unipolar state to a bipolar state determined by the duty cycle accompanied with higher discharge power and vibrational temperature. Bipolar discharge mode is beneficial to improve the efficiency of plasma ammonia synthesis because of it can strengthen the plasma discharge and increase the vibrational temperature. The ammonia synthesis rate and N2 conversion rate increased with the increase of the discharge power and vibrational temperature.

Enhancement of CrN-PEI adhesion by hardening and hydrophilicity PEI’s surface

The adhesion enhancement between a hard CrN coating and soft polyetherimide (PEI) is a key factor to effectively increase the usability of the CrN coated PEI as a wear resistant surface. Ion etching by a high pulsed power supply resulted in the surface hardening and hydrophilicity increasing of the PEI owing to the curing effect, which leaded to the weak atom’s vibration, proved by the absence of PEI’s characteristic infrared peaks, and the presence of the new polar adsorption infrared peaks. The CrN-PEI adhesion was enhanced, the wear resistance of the CrN coated PEI improved to the wear rate as low as 9.83 × 10-5 mm3·N−1·m−1.

Low Current Density Cathode Plasma Electrolytic Deposition of Aluminum Alloy Based on a Bipolar Pulse Power Supply

The present paper reported a novel bipolar-pulse cathodic plasma electrolytic deposition (BP-CPED) technique with a low current density. This newly developed CPED technique can break down the barriers of the existing CPED technique with higher current density. In this report, ceramic coatings were successfully prepared on aluminum alloy via the BP-CPED technique in an aqueous carbamide-based electrolyte. Data recording results in the reacting process show that there is the current density of the cathode below 0.15 A/cm2 and that of the anode below 0.035 A/cm2, which approximately reaches the level of conventional MAO technique. Interestingly, the addition of PEG into the electrolyte can further reduce the current density and effectively improve the coating quality. The kinetic of the BP-CPED process was discussed based on the evolution of current density/voltage-time curves and spark discharge phenomena. SEM observations illustrate that BP-CPED coatings possess a typical porous-surface feature. XRD analysis indicates that the coating was mainly composed of Al2O3 and Al4C3. Al2O3/Al4C3/ZrO2 composite coatings fabricated after Zr-doping reflected the successful Zr-incorporation into the coating, which demonstrated that the BP-CPED technique can be used to design the coating composition by the doping modification. The direct pull-off and thermal shock tests confirmed that new BP-CPED coatings obtained under the cathodic plasma discharge have excellent bonding strength. It is possible that this novel BP-CPED technique can provide a promising choice in developing the large-area CPED surface treatment for the industrial application.