Pulsed Power Conditions Research Articles

Microencapsulation of eutectic phase change materials for temperature management of the satellite electronic board

In the present study, microencapsulation of phase change materials (PCMs) has been carried out for effectively managing the temperature of satellite electronic boards. Eutectic fatty acids are chosen as the core material, and melamine–formaldehyde is utilized as the shell material to synthesize microcapsules tailored to meet the specific operating conditions of the electronic board. The synthesized microcapsules are characterized by different analyses. The Fourier transform infrared spectrometer (FTIR) indicates no chemical interactions between the core and shell materials, ensuring the stability of the encapsulation process. Differential scanning calorimeter (DSC) measurements show the highest encapsulation ratio of 73.26% for the core–shell ratio of 2:1. The MPCMs exhibit a well-defined core–shell structure, with a spherical shape and an average diameter of 4.5 µm, as observed through scanning electron microscope (SEM) and transmission electron microscope (TEM) analyses. Furthermore, the practical application of these microencapsulated PCMs (MPCMs) in managing the temperature of the satellite electronic board is explored. At constant electric powers of 4, 6, 8, and 10 W, the microcapsules introduce significant delays in reaching the critical temperature of 55 °C, with delays of 17, 12, 11, and 4.5 min, respectively. Additionally, under pulsed electric power conditions (8 W, 10 min on/80 min off), the maximum temperature with microcapsules reaches 50 °C, while without MPCMs, it reaches a much higher 73 °C. The results of this study demonstrate that the synthesized MPCMs are an effective and promising approach for temperature management of satellite electronic boards.

3D HfO2 Thin Film MEMS Capacitor with Superior Energy Storage Properties

AbstractCapacitors are ubiquitous and crucial components in modern technologies. Future microelectronic devices require novel dielectric capacitors with higher energy storage density, higher efficiency, better frequency and temperature stabilities, and compatibility with integrated circuit (IC) processes. Here, in order to overcome these challenges, a novel 3D HfO2 thin film capacitor is designed and fabricated by an integrated microelectromechanical system (MEMS) process. The energy storage density (ESD) of the capacitor reaches 28.94 J cm−3, and the energy storage efficiency of the capacitor is up to 91.3% under an applied electric field of 3.5 MV cm−1. The ESD can be further improved by reducing the minimum period structure size of the 3D capacitor. Moreover, the 3D capacitor exhibits excellent temperature stability (up to 150 °C) and charge‐discharge endurance (107 cycles). The results indicate that the 3D HfO2 thin film MEMS capacitor has enormous potential in energy storage applications in harsh environments, such as pulsed discharge and power conditioning electronics.

Accelerated Aging Experiment of IGBT under Pulsed Power and Reliability Studies

Pulsed power technology gives full play to the characteristics of high pulses in the form of short pulses, and gradually occupies a certain position in industrial applications. It needs to ensure stability and durability while ensuring that the working parameters are met, the switching performance is particularly important., therefore, the reliability study of IGBT power module becomes an inevitable requirement for reliability evaluation in engineering. This article mainly introduces the experimental method of the accelerated aging experiment of IGBT under pulsed power conditions. The electro-thermal simulation is carried out through PLECS and the low-power experimental platform is built to obtain experimental data. Finally, the experimental data is analyzed, and the change rule of the failure characteristic parameters with the aging process under the pulse power condition and the IGBT failure standard different from the typical operating condition are obtained.

Power-optimized, time-reversal pulse sequence for a robust recovery of signals from rigid segments using time domain NMR

Time domain NMR (TD-NMR) has been widely used on the analysis of liquids or liquid components in heterogeneous materials such as food, biological tissues, synthetic and bio polymers, oil-bearing rocks, biomasses and cement-based materials. The use of TD-NMR for studying solid and soft mater has been growing in number and variety of applications, mostly for organic systems where the detection of 1H signals is highly advantageous. However, the strong 1H–1H dipolar interactions in solids make the 1H FID to decay in the same order of the dead time of most commercially available NMR probe heads. Thus, solid echoes are often used for recovering signals from solid components. In this article we reinvestigate the time-reversal solid-echo pulse sequence proposed by Rhim and Kessemeier, seeking for optimal pulse power and timing conditions that maximize its efficiency on recovering 1H signals from rigid segments. We show that under these optimized conditions, which we denote as Rhim and Kessemeier - Radiofrequency Optimized Solid-Echo (RK-ROSE), the experiment can be more efficient than its most popular counterparts Solid-Echo (SE) and mixed-Magic Sandwich Echoes (mixed-MSE). Our results also suggest that, despite the finite pulse power, with current probe technology the RK-ROSE experiment is potentially able to provide an accurate estimation of rigid components, without relying on an external calibration using multiple standard samples, as usually done in SFC analysis of the FID signal. At last, we demonstrate that RK-ROSE can be adapted as a simple filter to supress signals from mobile segments in heterogeneous materials.

Residual stress control of Cu film deposited using a pulsed direct current magnetron sputtering

Residual stress of 10 μm thick copper (Cu) film deposited using direct current (DC) magnetron sputtering system was analyzed for various pulsed DC power conditions. It is found that the increase of pulse frequency at a fixed duty ratio of 80% from continuous wave (CW) to 100 kHz while maintaining the time average power significantly decreased the residual stress of Cu film from 21.75 MPa to 1.8 MPa. The decrease of pulse duty ratio further decreased the residual stress by showing 0.7 MPa at 60% of duty ratio and 50 kHz pulse frequency. Therefore, compared to CW power, Cu film with ~1/30 lower residual stress could be deposited by using DC pulse power. The decrease of residual stress by pulsing and by decreasing the pulse duty ratio while keeping the same time average power was related to the denser film density and smaller grain size of deposited Cu film caused by increased instant sputter power during the pulsing.

Comparative study of electrical breakdown properties of deionized water and heavy water under pulsed power conditions.

A comparative study of electrical breakdown properties of deionized water (H2O) and heavy water (D2O) is presented with two different electrode materials (stainless steel (SS) and brass) and polarity (positive and negative) combinations. The pulsed (∼a few tens of nanoseconds) discharges are conducted by applying high voltage (∼a few hundred kV) pulse between two hemisphere electrodes of the same material, spaced 3 mm apart, at room temperature (∼26-28 °C) with the help of Tesla based pulse generator. It is observed that breakdown occurred in heavy water at lesser voltage and in short duration compared to deionized water irrespective of the electrode material and applied voltage polarity chosen. SS electrodes are seen to perform better in terms of the voltage withstanding capacity of the liquid dielectric as compared to brass electrodes. Further, discharges with negative polarity are found to give slightly enhanced discharge breakdown voltage when compared with those with positive polarity. The observations corroborate well with conductivity measurements carried out on original and post-treated liquid samples. An interpretation of the observations is attempted using Fourier transform infrared measurements on original and post-treated liquids as well as in situ emission spectra studies. A yet another important observation from the emission spectra has been that even short (nanosecond) duration discharges result in the formation of a considerable amount of ions injected into the liquid from the electrodes in a similar manner as reported for long (microseconds) discharges. The experimental observations show that deionised water is better suited for high voltage applications and also offer a comparison of the discharge behaviour with different electrodes and polarities.

자동차 전장품용 무연솔더 접합부의 시리즈 시험 유효성

Abstract Due to environmental regulations (RoHS, WEEE and ELV) of the European Union, electronics and auto-motive electronics have to eliminate toxic substance from electronic devices and system. Specifically, reli-ability issue of lead-free solder joint have an increasing demand for the car electronics caused by ELV banning. The authors prepared engine control unit and cabin electronics soldered with Sn-3.0Ag-0.5Cu (SAC305). To compare with the degradation characteristics of solder joint strength, thermal cycling test (TC), power-thermal cycling test (PTC) and series tests were conducted. Series tests were conducted for TC and PTC combined stress test using the same sample in sequence and continuously. TC test was per-formed at -40~125 ℃ and soak time 10 min for 1000 cycles. PTC test was applied by pulse power and full function conditions during 100 cycles. Combined stress test was tested in accordance with automotive company standard. Solder joint degradation was observed by optical microscopy and environment scanning electron microscopy (ESEM). In addition, to compare with deterioration of bond strength of quad flat pack-age (QFP) and chip components, we have measured lead pull and shear strength. Based on the series test results, consequently, we have validated of series test method for lifetime and reliability of Pb-free solder joint in automotive electronics.Key Words : Pb-free solder, Solder joint, Series reliability, Automotive electronics, DegradationISSN 1225-6153Online ISSN 2287-8955

3-D Thermal Component Model for Electrothermal Analysis of Multichip Power Modules With Experimental Validation

This paper presents for the first time a full three-dimensional (3-D), multilayer, and multichip thermal component model, based on finite differences, with asymmetrical power distributions for dynamic electrothermal simulation. Finite difference methods (FDMs) are used to solve the heat conduction equation in three dimensions. The thermal component model is parameterized in terms of structural and material properties so it can be readily used to develop a library of component models for any available power module. The FDM model is validated with a full analytical Fourier series-based model in two dimensions. Finally, the FDM thermal model is compared against measured data acquired from a newly developed high-speed transient coupling measurement technique. By using the device threshold voltage as a time-dependent temperature-sensitive parameter (TSP), the thermal transient of a single device, along with the thermal coupling effect among nearby devices sharing common direct bond copper (DBC) substrates, can be studied under a variety of pulsed power conditions.

Light weight high temperature polymer film capacitors with dielectric loss lower than polypropylene

The dielectric and high voltage performance of polymethylpentene (PMP) is investigated and compared with biaxially-oriented polypropylene (BOPP) for high power density and high temperature capacitor applications. PMP has a melting temperature that is around 60 °C higher than BOPP, while still maintaining low dielectric loss and high charge–discharge efficiency that are comparable to the latter. Furthermore, PMP is the lightest commercial thermoplastic polymer with density of 0.83 g/cm3, which is 8 % lower than BOPP (0.9 g/cm3). PMP is a promising semicrystalline dielectric material that may replace BOPP for high temperature pulsed power and power conditioning applications.

Study on the Performance of High-Voltage Trigger Generators in Pulsed Power Conditioning System

Two-electrode graphite spark gap switch (TGSGS) is used as the main discharge switch and triggered by a reliable trigger generator in pulsed power conditioning system (PPCS). There would be 108 energy modules in PPCS working at the same time. The reliable operating and jitters of the trigger generators will have impact on the PPCSs performance. In this paper, the working modes of the TGSGS are discussed and the performance of trigger generators in PPCS is tested and presented. A protection strategy of the trigger generator in PPCS is introduced, and effect of the blocking capacitor on the trigger pulse transmission is analyzed and tested. The protection strategy of the trigger generator based on blocking capacitor and fuse can effectively prevent the energy anti-irrigation failure when the pulse transformer core saturated. The blocking capacitor has some effect on the trigger pulse transmission, and has the larger capacitance, getting the higher peak amplitude on the cathode of the TGSGS. It is tried to discuss the working characteristics of the thyristors, and proposes a selection reference of the thyristors in this and other similar applications. The combination of analysis and measurement would be useful for the selection of thyristors and other components.

A Simple Self-Breakdown Sharpening Switch With Low Jitter and Stable Breakdown Voltage

Normally, a three-electrode spark-gap switch is controlled by the application of an external trigger impulse. In this paper, a novel self-breakdown sharpening switch based on the three-electrode spark-gap switch is proposed. However, in this paper, the trigger electrode is connected to ground through a resistor, with the prespark between the trigger and the main electrodes providing the electrons and ions that initiate conduction of the main gap. A prototype sharpening switch with a breakdown voltage of 116.0 kV ± 1.0 kV and a breakdown time of 3.396 μs ± 0.036 μs is described. When compared with a conventional two-electrode spark-gap sharpening switch, the novel sharpening switch has both a more stable breakdown voltage and lower jitter, and the dc breakdown and impulse breakdown characteristics of the two types of switches are presented and compared. When the impedance of the resistor connected to the trigger electrode is high, it is demonstrated that both the value of this resistor and also the type of load have little effect on the characteristics of the novel switch. However, the breakdown voltage of the novel sharpening switch was found to be sensitive to the rise time of the input pulse from the trigger generator. The prototype sharpening switch has a lifetime at least 20 000 shots and is now in use in a major pulsed power conditioning system.

Study on a Magnetic Switch for Pulsed Power Conditioning System

In order to protect the key elements (e.g., Xe flashlamps) from being damaged by the trigger impulse in pulsed power conditioning system (PPCS), a magnetic switch is used for isolating the high-voltage nanosecond impulse. The magnetic switch in PPCS is working along with the initial magnetization curve. The working principle and performance of the magnetic switch in PPCS is presented. Fe-based nanocrystalline is adopted as the material of magnetic core. According to the specific application, the dynamic characteristics of Fe-based nanocrystalline under nanosecond impulses were obtained experimentally. As the magnetization rate increases, the average relative permeability decreases due to magnetic viscosity and eddy current. The measured parameters of unsaturated inductance, saturated inductance, and saturation time are in agreement with the calculation ones. Finally, the experimental results of the magnetic switch in PPCS are presented.

Novel Ferroelectric Polymers for High Energy Density and Low Loss Dielectrics

The state-of-the-art polymer dielectrics have been limited to nonpolar polymers with relatively low energy density but ultralow dielectric losses for the past decades. With the fast development of power electronics in pulsed power and power conditioning applications, there is a need for next-generation dielectric capacitors in areas of high energy density/low loss and/or high temperature/low loss polymer dielectrics. Given limitations in further enhancing atomic and electronic polarizations for polymers, this Perspective focuses on a fundamental question: Can orientational polarization in polar polymers be utilized for high energy density and low loss dielectrics? Existing experimental and theoretical results have suggested the following perspectives. For amorphous polar polymers, high energy density and low loss can be achieved below their glass transition temperatures. For liquid crystalline side-chain polymers, dipole mobility is so high that they saturate at relatively low electric fields, and only li...

Design and Construction of a Trigger Generator Based on Pulse Transformer for Spark Gap Switch

A two-electrode graphite spark gap switch is used as the main discharge switch and triggered by a reliable trigger generator in a pulsed-power conditioning system. The trigger generator based on resonant charging of a pulse transformer is constructed. An appropriate ratio can be obtained when using resonant charging based on a core-type pulse transformer. The charging time is dependent on the leakage inductance and the capacitance of the primary and secondary capacitors. The stray resistance and magnetizing inductance of the resonant charging circuit have an impact on ratio and energy transmission efficiency. A dry-type pulse transformer with a load of 1.08 nF, an output voltage of more than 130 kV, and a winding ratio of 65 is presented. A self-breakdown three-electrode output switch is used to shorten the rise time of the output impulse. The deviation of the self-breakdown voltage of the self-breakdown three-electrode output switch is much smaller than that of the self-breakdown two-electrode output switch. It assures that the trigger generator has a low jitter of output impulse when a lot of energy modules work simultaneously. The output impulse of the trigger generator with a peak value of more than 120 kV and a rise time of less than 30 ns can trigger the two-electrode graphite spark gap switch reliably.

Analysis and realization of magnetic switch in pulsed power conditioning system

When two-electrode spark gap switches are applied to main discharging circuit of pulsed power conditioning system, trigger generators will be needed. To guarantee triggering reliability and protect other key components in the pulsed power conditioning system, such as pre-ionization branch and xenon lamp, magnetic switch is needed to insulate the high triggering voltage in the main discharging circuit. In this paper, starting from the analysis of the working principle of the discharging circuit, we present the solution of Fe-based nanocrystalline alloy switch. Specifically, we provide the basis of theoretical calculation and the method of material selection for the design and realization of this magnetic switch. Via the performance tests in pulsed power conditioning system, the validity of material selection and parameter design is proved. This paper provides a reference for the engineering design and application of magnetic switches in huge pulsed power systems.

Control of molybdenum disulfide basal plane orientation during coating growth in pulsed magnetron sputtering discharges

Molybdenum disulfide coatings were grown under selected mid-frequency bi-polar pulsed direct current power conditions to control the basal plane orientation relative to the substrate, from parallel (002) to perpendicular (100). Growth mechanisms under different conditions were made apparent by the observed trends. The highest (002)/(100) orientation ratios were obtained with growth rates near 1 atomic layer per second accompanied by high energy ion bombardment (up to 175 eV). These conditions allowed maximum surface diffusion of deposited atoms before burial by incident material or removal by desorption and resputtering. Additionally, high energy ion bombardment during pulsed deposition produced defects on the otherwise inert MoS 2 (002) surface that further enabled adsorption and crystal growth. For growth rates of less than one monolayer per second coupled with low ion energies and fluxes, coatings exhibited strong (100) orientation. Under these low growth rate conditions, the burial rate was still higher than the desorption rate on the (100) surface, and the lack of energetic ion bombardment permitted uninterrupted growth of crystals in this orientation. For sliding wear tests conducted in humid air, the tribological performance of the coatings demonstrated a strong dependence on (002)/(100) ratios.

Capacitor Bank Module for a Multimegajoule Energy Storage

Laser megajoule (LMJ) is a laser facility being built by the French nuclear science directorate, Commissariat a l'Energie Atomique. This facility is a large flashlamp pumped laser (1.8-MJ optical output). The pulsed power conditioning system of LMJ is based on a modular design of 480 modules (400-MJ energy capacitor bank). A new capacitor bank module (CBM) for the LMJ power conditioning system has been developed by the Institute of High Current Electronics (IHCE, Tomsk) in collaboration with International Technologies for High Pulsed Power (France). Two such modules were produced and tested in IHCE. The main parts of the CBM are the following: high-voltage power supplies, command control system, air conditioning system, capacitor block, and cables delivering the energy to a load. The parameters of the module are the following: total rated capacitance of 2900 (+4%) muF, charging voltage up to 24 kV, peak current amplitude of 240 kA, peak stored energy up to 864 kJ, pulsewidth at 10% of peak power of 360 mus, dimensions of 2.3 times 1.5 times 2.5 m3, and weight of ~2500 kg. In nominal regime (24-kV charging voltage, 40-m length cables), the energy delivered to flashlamps in each channel is 74 kJ (86% efficiency). No failures were observed in more than 1000 test shots, and all parameters of the CBM are well within the requirements. Detailed description of the module design, performance, and test results are stated in this paper.

An inductive scheme of power conditioning at mega-Ampere currents

This work describes an inductive energy storage scheme intended for power multiplication at mega-Ampere currents. The key power multiplication element of the scheme is an opening switch generating the voltage of inductive origin. The switch represents an additional volume with magnetically accelerated solid-state or plasma conductor between the generator and the load. Motion of the conductor increases the inductance of the volume. A sufficiently fast increase of this inductance at the end of magnetic energy storage time ensures power multiplication. A critical requirement for the accelerated conductor is the possibility of temporal profiling of the inductance increase. A proof-of-principle experiment at GIT12 shows that such profiling is possible. We suggest a simple analysis of the scheme efficiency and illustrate this analysis for a multi-mega-Ampere class generator. The scheme is alternative to existing inductive energy storage technologies for pulsed-power conditioning at high currents.

HIGH POWER SIC PIN RECTIFIERS

High voltage PiN rectifiers made using conventional semiconductor materials such as Silicon are restricted to less than 20 kHz and less 120°C operation, thereby severely limiting the availability of advanced electronic hardware used for power grid (also called electric utility), energy storage, pulsed power, intelligent machinery and ultra high voltage solid state power conditioning. Such applications require high power density, very high frequency, and high temperature rectifiers to realize reasonably sized systems. SiC PiN Rectifiers are expected to play an enabling role in a variety of such high voltage applications because they have been shown to offer 2 to 3 orders of magnitude faster switching, high junction temperature capability, high current density operation, and much higher power densities as compared to Silicon.

Modeling of transient nonequilibrium phenomena in an inductively coupled plasma under pulsed power conditions

A time-dependent two-temperature model is developed to simulate the behavior of an argon radio frequency plasma under transient nonequilibrium conditions, with emphasis to shed light on the temporal and spatial evolution of the nonequilibrium phenomena occurring in pulsed power plasmas. The results show that the effects of changes in input power on the thermal nonequilibrium and the ionization nonequilibrium are most noticeable at the early stages of pulse on and off. The observed deviation from thermal equilibrium during pulsation is more pronounced in the fringes of the plasma and near the wall of the torch. In the central region, the influence is less significant and the plasma remains in a quasilocal thermal equilibrium state. The temporal evolution of the ionization nonequilibrium does not keep pace with that of the thermal nonequilibrium, and the relaxation process of the electron number density is slower and smoother. The effects of operating conditions on the transient behavior of the nonequilibrium situations under pulsed power conditions are also examined. It indicates that, for materials processing, a pulse duration between 2 and 10 ms is adequate for rf plasmas operated in pulse-modulated modes.