High Voltage Capacitor Research Articles

Two dimensionalization induced enhancing dielectric anisotropy of titania

Abstract Two dimensionalization of dielectric oxides will lead to significant variations of the dielectric properties in comparing with their bulk counterparts. To clarify the longstanding controversy how indeed dielectric properties would change is a critical prerequisite and highly demanded by the correlated scientific community and electronic industry. Here, taking titania as an example, a theoretical study by ab-initio calculations is performed for predicting the dielectric property evolution in combining with the structure transformations. Highly enhanced dielectric constant anisotropy is found that out of plane reduces significantly differed from those enlargement predictions, but electronic screening in plane enhances. While for the breakdown strength, which is always ignored in theoretical investigation, it also demonstrates that permittivity and breakdown strength can be enhanced at the expense of each other during two dimensionalization. The anisotropy between permittivity and breakdown strength can cause a much higher dielectric energy density. Such findings are very helpful for designing future atomic scale electronic and optical devices such as high voltage capacitor, excellent gate dielectrics for high frequency field effect transistor (FET) with two-dimensional oxide dielectrics.

Put strong limits on all proposed theories so far assessing electrostatic propulsion: Does a charged high-voltage capacitor produce thrust?

Several claims appeared in the literature that a charged high-voltage capacitor produces thrust. This dates back to the so-called Biefeld-Brown effect that was later explained as a Corona-wind effect. However, part of the claim was that the capacitor still moves even if no ionization takes place and a dielectric is used. Recently, theories appeared supporting such an electrostatic propulsion-scheme. Here we describe an experimental-setup allowing to measure weight changes/forces of capacitors up to 10 kV, eliminating important side-effects from high-voltages down to±0.3 mg. No force was detected for a variety of configurations ruling out most theories by many orders of magnitude.

Analysis of the Formation of Welded Joints from Non-Ferrous Alloy

The features of the production of welded joints from non-ferrous alloys are considered. The disadvantages of the used capacitor welding methods are described. To reduce the possibility of intermetallic compounds, it is proposed to use high-voltage capacitor welding with induction-dynamic drive (HVCW with IDD) on super-rigid modes of action. The technological scheme methods of HVCW with IDD are given, the physical nature of the impulse process is described. The results of comparative analysis of the waste of thermal energy depending on the technological method and roughness of the welded surfaces, as well as the ratio of thermal and mechanical energies for each method of HVCW with IDD are given.

Design and Development of the High Voltage Capacitor Step-down Power-taking Device

The designed device uses high voltage capacitor in series with a voltage transformer to take power. It uses the capacitance voltage resistance and the transforming characteristics of voltage transformer, and the monitoring system is supplied with power by subsequent rectifier filtering and switching circuit. As high voltage capacitor step-down has the problem of limited energy, the set of device uses voltage transformer to increase power output, and the required power are provided to the load end on the basis of the changing of the load end power, and through the relay’s on or off to control the connection or disconnection of the front-end resistance. 10kv voltage transformer are used for 110kv line, and the primary side voltage of the voltage transformer is controlled at 10kV by using the voltage stabilizing function of the rear-connected circuit. Through The overall test of power output is stable, the device operates well.can provide stable and effective low-voltage power supply for the on-line detection device of 110kV high-voltage multiple circuit..

Machine Learning Based Operating Region Extension of Modular Multilevel Converters Under Unbalanced Grid Faults

The capacitor voltage ripples of the modular multilevel converter (MMC) are increased under unbalanced grid fault conditions. Since high capacitor voltage ripples deteriorate their lifetimes and may even cause tripping of the MMC system, it is important to restrict them. To this end, it is well known that injecting double fundamental frequency circulating currents can reduce the capacitor voltage ripples. However, finding a proper circulating current reference to achieve desired ripples analytically is complicated. This letter proposes an alternative method to quickly calculate the proper circulating current references without analytical computations, which is achieved by an artificial neural network (ANN) trained to approximate the relationship between circulating current references and capacitor voltage ripples. The training data are first extracted from a detailed simulation model of the MMC. Afterward, the ANN is trained by the input-output data to obtain the mapping relationship, which is then used to derive the desired circulating current references. Both the simulation and the experimental results verify the practicability of the proposed method, where the operating region can be extended 30% at a minimum in all testing conditions.

Study on Impact Response Characteristics of Capacitive Voltage Transformer

Under the impact voltage, the internal capacitive components of the capacitive voltage transformer are subjected to different voltages. Understanding the impulse response characteristics of the capacitive voltage transformer is of great significance for analyzing the internal insulation fault of the capacitive voltage transformer. In this paper, from the disintegration of a 500kV capacitive voltage transformer, based on the actual measurement of the capacitor and its internal components, the distributed parameter model of the capacitive voltage transformer is established. The response of the capacitive voltage transformer to the surge voltage is analyzed under the condition of lightning intruding wave and long line closing. The analysis shows that the capacitive element of the high-voltage side capacitor divider of the capacitive voltage transformer is subjected to the first and last ends of the capacitive voltage transformer. The voltage is higher than other capacitive components; when a partial capacitive component breaks down in the capacitive voltage divider, the voltage drop of the normal component under the same surge voltage increases, which will accelerate the damage of the capacitive component caused by the surge voltage; analysis conclusion and disintegration The results are in agreement and are of great significance for analyzing the internal insulation damage of capacitive voltage transformers.

Research on electromagnetic radiation interference of high voltage pulse device

In view of the strong electrostatic field interference caused by the miniaturization of high voltage pulse capacitor circuit, the protection method of electronic equipment under the strong electrostatic field interference of high voltage pulse device is proposed. Based on the background of miniaturization of all electronic security system, a high-voltage capacitor pulse discharge model is established. The surrounding radiation of high-voltage capacitor instantaneous discharge is simulated by using the COMSOL software. The electromagnetic radiation interference of high-voltage capacitor to the system is analyzed, and the anti-radiation interference measures are proposed based on the electromagnetic shielding mechanism. It provides a basis for the actual circuit design and structure layout, and provides a reference for the stability and safety of the electronic security system and further miniaturization development.

Study of pulsed laser beams and magnetic field on radish seeds

In this work we report a study on the influence of innovative pulsed stresses utilizing an UV laser and a homemade generator of magnetic field on radish seeds (Raphanus sativus L.) growth. We analysed the seed germination and seedling growth. The UV pulsed laser was an excimer KrF operating at 248 nm, 23 ns of pulse duration, with a laser fluence of about 40 mJ/cm2. The generator of pulsed magnetic field was realized by the electric discharge on a coil of a high voltage capacitor of 150 μF, 60 kV . The magnetic field pulse waveform exhibited damped oscillations at 215 kHz with a maximum intensity of 400 mT . Groups of uniform radish seeds were exposed to laser pulses at five different doses: 30000 shots (KrF/1), 80000 shots (KrF/2), 145000 shots (KrF/3), 225000 shots (KrF/4) and 275000 shots (KrF/5). Other groups were exposed to magnetic field at eight different doses: 3600 shots (MF/1), 7200 shots (MF/2), 10800 shots (MF/3), 14400 shots (MF/4), 18000 shots (MF/5), 21600 shots (MF/6), 32400 kshots (MF/7) and 36000 shots (MF/8). Simultaneously, untreated seeds were used as control. All treatments were performed at room temperature. Both untreated and treated seeds were transferred in Petri dishes and followed for their germination and seedling growth up to 96 h. The results showed that the stress induced by UV laser photons brought a significant stimulation on root growth which may contribute to improve the performance and the productivity of the plants. On the contrary, all physical stresses induced by magnetic fields did not have effect on seed germination, as well as on cell elongation growth and on hypocotyls in comparison to control seeds.

A 624 V 5 A All‐GaN Integrated Cascode for Power‐Switching Applications

An all‐GaN integrated cascode device with an output current of 5 A, threshold voltage of +0.65 V and breakdown voltage of 624 V is demonstrated. Compared with the commercial 600 V hybrid GaN plus Si cascode device (TPH3202), the integrated cascode exhibits a significantly reduced delay time when switched at 200 V and 2.7 A. This is attributed to the absence of a Si metal–oxide–semiconductor field‐effect transistor (MOSFET) driver, leading to a much smaller input capacitance as indicated by the high voltage capacitance measurements. In addition, the integrated cascode device shows a reduced ringing effect due to monolithic integration. When compared with commercial 600 V standalone GaN devices (GS66502B and GS‐065‐004), a reduced Miller effect is observed for the integrated cascode when switched under low gate‐driving current conditions. The results demonstrate the advantages of the cascode device to switch with low gate‐driving current using cheaper, faster, and more efficient gate drivers.

Optimized Design of Multi-MHz Frequency Isolated Auxiliary Power Supply for Gate Drivers in Medium-Voltage Converters

This article presents the design and optimization of a suitable topology for an isolated dc–dc auxiliary power supply with high isolation voltage and low coupling capacitance. The converter consists of a GaN HEMT inverter operating at 6.78 MHz, an LCC resonance tank, and a class-E low d v /d t rectifier. Furthermore, the galvanic isolation is implemented using a coreless planar transformer that enables higher insulation voltage with similar or better converter efficiency compared to designs using a magnetic material. An analytical design methodology is developed, however, SPICE investigations show that optimal designs might lie outside the validity of the design equations. Consequently, a virtual prototyping tool is developed based on a genetic algorithm with numerical simulations, and in turn, is used to optimize the converter. The optimization algorithm maximizes the converter efficiency while minimizing the transformer size. Prototypes are constructed based on the resulting Pareto front. Experimental results show the validity of the simulated results. Prototypes transferring power up to 15 W with a peak efficiency of 81% are shown. The selected topology enables insulating voltages exceeding 40 kV and coupling capacitances below 10 pF.

High voltage capacitor charging system in application of multi-stage coil gun

High voltage capacitor charging system applied for multi-stage coil consisting of a coil arrangement as a launcher and requires much energy to work. However, large currents and the high voltage required are very limited. High voltage capacitor banks are used as an alternative for energy storage. This capacitor bank is supplied by batteries and requires a charging device. The process of charging a high voltage charging capacitor requires a DC-DC Converter device. In this article, to supply energy to the coilgun, a High Voltage Capacitor Bank is used. 10 capacitors are connected in parallel charging the capacitors with a voltage divider system to avoid swelling at the capacitor charge. This device has been successfully implemented in Multistage Coil Gun. The results achieved indicate an increase in voltage capability up to 1.8 kV DC.

Low-crystalline FeOx@PPy hybridized with (Ni0.25Mn0.75)3O4@PPy to constructed high-voltage aqueous hybrid capacitor with 2.4 V

The operating voltage of aqueous hybrid capacitors are generally limited to 2 V due to the decomposition of water, which significantly impede the progress of energy density. Herein, the porous low-crystalline FeOx nanorod array on carbon cloth is prepared by the novel electrochemical Li+ pre-insertion method, and a 2.4 V high-voltage aqueous hybrid capacitor device is successfully obtained after matching with the nickel doped (Ni0.25Mn0.75)3O4@PPy nanoprisms array. The low-crystalline structure of FeOx preserved during the first Li+ insertion and space created via the elimination of low-crystalline Li2O dramatically provides sufficient electronic and ionic transfer channels. In addition, surface polypyrrole (PPy) stabilization is employed to further enhance electron conductivity and electrode stabilization. Benefitting from increasing active sites, fast ion diffusion and electron transfer the obtained low-crystalline FeOx@PPy electrode exhibits improved electrochemical performance, especially for capacitance and stability. Moreover, the aqueous hybrid capacitors (Ni0.25Mn0.75)3O4@PPy//FeOx@PPy device delivers a high energy density of 72.4 Wh kg−1 with the ultra-high voltage, and admirable cycling stability (94.7% retention after 4000 cycles). Our work highlights the novel electrochemical Li+ pre-insertion method to achieve superior low-crystalline electrodes materials and designs the high-voltage aqueous hybrid energy storage devices.

A proposal to design and develop a microwave weed controller for agricultural use

Problems based on agricultural activities are increasingly adversely affecting the environment and living health mostly due to chemical inputs used which cause concerns globally. One of the non-chemical weed control methods is the microwave weed control method. The purpose of this research is to propose an environmentally friendly agricultural machine design that can be an alternative to harmful chemicals used in weed control. In this study, microwave generators (magnetron) receive their energy from a generator fed from the tractor shaft. Multiple magnetrons, control, and leakage unit, and waveguides operating at 2.45 GHz ISM will be used. The design includes a magnetic shunt transformer, a high voltage capacitor, a filter, and a cooling fan with each magnetron where microwave leaks that occur during applications can be controlled and magnetron activities can also be monitored. Field applications and tractor working conditions will be analyzed and the device will be re-designed and developed according to the needs. In this study, unlike the other studies, more than one magnetron will be used and the device is designed for open agricultural areas applications. This design and application area differences are the most important feature that distinguishes this study from others, and it is made for the first time. Its use is expected to occur in all countries with similar characteristics for agricultural production.

Ageing: Causes and Effects on the Reliability of Polypropylene Film Used for HVDC Capacitor

It is well-known that the high-performance polymeric dielectric films used for high-voltage DC capacitors should have outstanding capabilities in terms of electrical and mechanical properties in order to face harsh operating conditions. Many factors limit the ability of these thin films to face different and growing stresses according to modern electrical requirements. Microstructure properties, additives, impurities, defects formed during manufacturing as well as applied stress types significantly affect the performance of dielectric films and their operational lifetime. This paper presents a comprehensive review of the factors which affect the ageing, degradation and breakdown of metallised polypropylene (PP) capacitors films. The effects of microstructure, surface morphological properties, mechanical properties and defects on the reliability of biaxially oriented polypropylene films (BOPP) are studied. In addition, the phenomena affecting dielectric performance and ageing mechanisms which are induced by electrical, thermal and electrothermal stresses are discussed.

The Research on Additional Errors of Voltage Transformer Connected in Series

The series summation method is an important method in the calibration of the voltage coefficient (VC) of the standard voltage transformers (VTs), in which the key step is connecting a fullyinsulated VT and a semi-insulated VT in series, and comparing them with the third VT under test. Caused by the imperfect electrical shielding of the serially-wound VTs, additional errors are introduced in the calibration. By analyzing the cause of the additional errors in the serial connection of the VTs, two methods were designed in this paper to measure the additional errors. The proposed methods were harnessed to measure the additional errors for a serial connection of a 35 kV fully-insulated two-stage voltage transformer (TSVT) and a 35 kV semi-insulated TSVT. The results show that the two methods give a consistency of better than 1.0 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> in ratio error and 2.0 μrad in phase displacement, respectively. The accurate measurement of the series additional errors and the correction of them significantly improve the accuracy of the VC measurement of a 110/√3 kV TSVT based on the series summation method. Furthermore, the VC measurement result is verified by the consistency of the series summation method with the series additional errors corrected and the high-voltage standard capacitor method.

Internal insulation condition identification for high-voltage capacitor voltage transformers based on possibilistic fuzzy clustering.

The internal insulation condition of capacitor voltage transformers (CVTs) is a key influence factor that affects their measurement performance and safe operation. However, the internal insulation would age along with long-time operation and degrade due to environmental factors, and once the insulation degradation grows, serious damage and even explosion may happen in CVTs; hence, it is necessary to monitor the internal insulation condition of CVTs, and the fault type and fault degree need to be identified. In this paper, a data-driven internal insulation condition identification method for CVTs is proposed. Both the amplitude and phase of the output voltage of CVTs are collected, and then, recognition models based on the combination of the output voltages and distribution topology of CVTs in substations are built. A possibilistic fuzzy clustering method is used to monitor the internal insulation condition of CVTs, and different types and different degrees of insulation faults could be identified effectively. Finally, the proposed method is verified in several cases; not only the preset typical faults in the method could be identified effectively but also the faults beyond the preset faults could be diagnosed.

Analysis of thermodynamic processes under high-voltage condenser welding with inductive dynamic drive

When obtaining fixed joints of different thickness from dissimilar materials, there arise difficulties associated with various thermophysical properties, and the likelihood of occurrence of intermetallic phases under chemical interaction. The use of super hard modes of thermodynamic effect during high-voltage condenser welding (HCW) provides localizing heat generation in the contact zone of the weld surfaces, activating the surface layers through converging the surfaces with the displacement of molten metal to the periphery of the contact zone and forming bonding in the solid phase.Recommendations are given for the use of technological methods of high-voltage capacitor welding depending on the combinations of welded alloys. A description of the nature and physical processes occurring at each technological reception is given.It is shown that the energy stored in the capacitor banks is spent on heat and power action. Variation of the mass of the induction - dynamic drive pusher and its inductance enables to adjust the ratio of thermal and mechanical components of the HCW process.The energy dispersion analysis of the experimental compounds obtained from dissimilar alloys confirms the absence of diffusion in high-voltage capacitor welding under super-rigid exposure modes.

Supplier Selection and Performance Evaluation for High-Voltage Power Film Capacitors in a Fuzzy Environment

Rapid advances in technology have shortened the upgrade and replacement cycles in industries such as electronics, household appliances, and communication technologies. Within these industries, high-voltage power film capacitors have become indispensable electrical components due to their good electrical performance and high reliability. The selection and evaluation of suppliers of these capacitors is therefore increasingly important. Suppliers play a crucial role in the electronics industry; the quality of their products determines the degree to which the quality of the final product can be guaranteed. Supplier quality also affects the ability of all the members in a supply chain to control costs. Evaluation by decision-makers is highly significant in the supplier selection process. However, when the opinions of multiple decision-makers are combined, issues such as cognitive differences, fuzzy linguistics, and uncertainty are common. This study presents a supplier performance index SPL and derives the estimates of the index SPL and its statistical properties. The proposed index is not only helpful for the accurate measurement of supplier performance; it can also reduce cognitive differences among evaluators in the decision-making process (that is, the sample variability associated with the Likert scale). Evaluation scores for each criterion for the linguistic labels are converted to triangular fuzzy numbers in order to reduce ambiguity. Subsequently, integrated crisp values are obtained by defuzzification in a fuzzy inference system. A real-world case study of the supplier selection of high-voltage power film capacitors is provided to illustrate the efficacy of the proposed method.

Stacked High Voltage Al Electrolytic Capacitors Using Zr-Al-O Composite Oxide

A stacked high-voltage (900 V) Al electrolytic capacitor made with ZrO2 coated anode foils, which has not been studied so far, is realized and the effects of Zr-Al-O composite layer on the electric properties are discussed. Etched Al foils coated with ZrO2 sol are anodized in 2-methyl-1,3-propanediol (MPD)-boric acid electrolyte. The anodized Al foils are assembled with stacked structure to prepare the capacitor. The capacitance and dissipation factor of the capacitor with ZrO2 coated anode foils increase by 41 % and decrease by 50 %, respectively, in comparison with those of Al anode foils. Zr-Al-O composite dielectric layer is formed between separate crystalline ZrO2 with high dielectric constant and amorphous Al2O3 with high ionic resistivity. This work suggests that the formation of a composite layer by coating valve metal oxide on etched Al foil surface and anodizing it in MPD-boric acid electrolyte is a promising approach for high voltage and volume efficiency of capacitors.

A New Design Approach to Mitigating the Effect of Parasitics in Capacitive Wireless Power Transfer Systems for Electric Vehicle Charging

This paper introduces a new design approach to mitigate the effect of parasitic capacitances and achieve high performance in large air-gap capacitive wireless power transfer (WPT) systems for electric vehicle (EV) charging. In a capacitive WPT system for EVs, the vehicle chassis and roadway introduce multiple parasitic capacitances that can overwhelm the coupling capacitance and severely degrade power transfer and efficiency. The proposed approach addresses this challenge by employing split-inductor matching networks, which allow the complex network of parasitic capacitances to be simplified into an equivalent four-capacitance model. The shunt capacitances of this model are directly utilized as the matching network capacitors, hence, absorbing the parasitic capacitances and eliminating the need for discrete high-voltage capacitors. A systematic procedure is developed to accurately measure the equivalent capacitances of the model, enabling the system’s performance to be reliably predicted. The proposed approach is used to design two 6.78–MHz 12-cm air-gap prototype capacitive WPT systems with capacitor-free matching networks. The first system transfers up to 590 W using 150-cm2 square coupling plates and achieves an efficiency of 88.4%. The second prototype system transfers up to 1217 W using 118-cm2 circular coupling plates, achieving a power transfer density of 51.6 kW/m2. The measured output power profiles of the two systems match well with their predicted counterparts, validating the proposed design approach.