Capacitance Of Capacitor Research Articles

Dual-functions of the carbon-confined oxygen on the capacitance and cycle stability enhancements of Zn-ion capacitors

Zinc-ion capacitors (ZICs) are promising energy storage devices due to their balance between the energy and power densities inherited from Zn-ion batteries and supercapacitors, respectively. However, the low specific capacitance of carbon cathode materials and the dendrite growth on Zn anode have set fatal drawbacks to their energy density and cycle stability. Herein, we demonstrate that, in 1 M Zn(CF3SO3)2/DMF (N, N-dimethylformamide) electrolyte, confining oxygen in carbon cathode materials via high-energy ball milling can synergistically introduce additional pseudocapacitance on the cathode side while suppressing the dendrite growth on Zn anode side, which jointly lead to high energy density (94 Wh kg−1 at 448 W kg−1) and long cycle stability of ZICs. The hydroxyl group in carbon cathode can be transformed to C—O—Zn together with the release of protons during the initial discharge, which in turn stimulates the defluorination of CF3SO3− anions and formation of ZnF2 on both cathode and anode. The ZnF2 formed on the surface of the Zn anode suppresses the dendrite growth by regulating the Zn2+ deposition/stripping in a reticular structure, resulting in the excellent cycle stability. This work provides a facile strategy to rationally design and construct high energy and stable ZICs through engineering the oxygen-bearing functional groups in carbon cathode materials.

Perencanaan Pompa untuk Mempercepat Waktu Pengisian Oli di PT KSB Indonesia

In this study, specifications & design of the pump to used will be analyzed, then performance the oil pump is known, and effect of the oil pump on the ISP 3600 Trailer pump assembly process is analyzed. This research method begins with problem identification, literature study, analysis & optimization, design planning, fabrication process, assembly process and testing, then analyzed to obtain results in accordance with the objectives. Results this testing use a gear pump with minimum power of 67.15 Watts, using electric motor that has a minimum torque of 1.081 N.m and minimum power of 0.2125 HP, and using minimum capacitor capacity of 24.31 µF. This test uses Fuchs Renolin B46 Plus oil. Results this testing obtain a discharge of 16.789 l/min and charging time of 12.21 minutes per 205 liters.

Research of heat conductivity of quartz material

In the article the results of a study of heat conductivity and thermal resistance of quartz-containing materials were presented. The object of the study was a quartz mineral from the Aktas deposit, located in the Ulytau district of the Karaganda region. The initial size was a piece of quartz mineral measuring 5–10 mm, which was disassembled mechanically. To prepare the samples under study, quartz powder 0.2 mm thick, crushed by the electric pulse method, was used. Electropulse technology is one of the methods based on the influence of Yutkin, accompanied by the formation of a specially formed high-voltage pulsed electrical discharge inside a volume of liquid. The pulse discharge frequency of the electrohydropulse installation for grinding the mineral to the required fraction was f = 3 Hz, the pulse capacitor capacitance C = 0.4 μF, the pulse discharge voltage U = 18–37 kV. The samples under study were made in the following dimensions: width 100 mm, length 100 mm, height 25 mm. To evaluate the thermophysical properties of manufactured samples in a stationary mode, the ITP-МG4 “100” installation was used, which determines the heat conductivity and thermal resistance of materials for thermal insulation of industrial equipment and pipelines in accordance with GOST 7076, based on the thermoelectric method, and GOST 30256, based on the thermal probe method. As a result of the study, a graph of the temperature dependence of heat conductivity and thermal resistance of quartz-containing materials was obtained. Based on the results obtained, it was established that the thermophysical parameters of the sample containing quartz are lower compared to the sample consisting of cement.

Reverse water-gas shift in a novel spark-coupled dielectric barrier discharge plasma: Effects of electrode structure and gas parameters

The reverse water–gas shift (RWGS) reaction holds promise for producing raw materials used in the synthesis of high-value chemicals. However, the reaction is often hindered by low CO2 conversion rates at atmospheric pressure and low temperatures. To overcome this limitation, this study developed a novel reactor based on strengthened spark-coupled dielectric barrier discharge (SSCDBD) without a catalyst, leveraging local high temperatures to enhance performance. The effects of reactor structure and gas parameters on conversion rate and energy efficiency were systematically investigated. The results indicated that the SSCDBD device notably improved CO2 conversion compared to conventional plasma techniques, such as dielectric barrier discharge (DBD), spark discharge, and spark-coupled dielectric barrier discharge (SCDBD), with respective increases of 1000 %, 12.65 %, and 2.79 %. Notably, varying the length of the auxiliary electrode affects the capacitance of the equivalent capacitor and, consequently, the discharge intensity. Furthermore, Increasing the electrode length from 4 cm to 20 cm improved the CO2 conversion rate from 43.7 % to 59.8 %. Moreover, CO2 conversion was positively correlated with the discharge distance, which also affected the volume of the electric arc. However, distances exceeding 1.2 cm interfered with arc formation. At a CO2:H2 molar ratio of 1:1, with an auxiliary electrode length of 12 cm and a discharge distance of 0.8 cm, the maximum CO2 conversion rate of 66 % was achieved at a total feed flow rate of 100 mL min−1, while maintaining a CO selectivity higher than 99 %. Additionally, with a total feed flow rate of 400 mL min−1, CO2 conversion reached 29 % and energy efficiency peaked at 6.34 %.

Production and research of tungsten carbide powder from VA grade tungsten metal waste in aviation kerosene

Purpose. Obtaining and studying the composition, structure and properties of tungsten carbide powder from VA grade tungsten metal waste in aviation kerosene. Methods. Tungsten carbide powder from tungsten metal waste of the VA brand was obtained in the following sequence. The reactor was filled with a working medium – aviation kerosene of the TS-1 brand, the waste was loaded into the reactor. Electrodes were mounted from the same waste tungsten of the VA brand. The mounted electrodes were connected to a pulse generator. The necessary electrical parameters of the installation were set: the capacitance of the condensers is 42.0–43.5 UF; the voltage on the electrodes is from 115–120 V; the pulse repetition rate is 50–55 Hz. The resulting tungsten powder was studied using: a scanning electron microscope QUANTA 600 FEG; a particle size analyzer Analysette 22 NanoTec; an energy-dispersed X-ray analyzer from the company EDAX; X-ray diffraction on a diffractometer Rigaku Ultima IV. Results. Based on the conducted experimental studies, a new method for producing tungsten carbide powder has been developed, characterized in that the powder is obtained by electroerosive dispersion of tungsten metal waste of the VA brand in aviation kerosene at a capacitor capacity of 42.0–43.5 UF, an electrode voltage of 115–120 V and a pulse repetition frequency of 50–55 Hz. It has been experimentally established that spherical and elliptical particles of tungsten carbide powder W2C have sizes from 2.26 microns to 90.72 microns with an average volumetric diameter of 20.2 microns and contain carbon on the surface. Conclusion. The production of tungsten carbide suitable for industrial use at low energy costs from metal waste has shown high efficiency of the technology of electroerosion dispersion.

DEVELOPMENT OF DUAL-SWITCHES BRIDGELESS PFC TOTEM-POLE SEPIC CONVERTER FOR LED DRIVER APPLICATION

This paper presents a Dual-Switch Bridgeless Power Factor Correction (DSBPFC) Single Ended Primary Inductor Converter (SEPIC) with Totem-Pole circuit structure for LED Driver Application. The conventional Full-Bridge Rectifier (FBR) SEPIC converter has five diodes, four in the rectifier bridge and one in the SEPIC. In addition, the FBR SEPIC converter has several drawbacks, including low power factor (PF), high current harmonics (THDi), and high output voltage ripple, due to the combination of two operation circuits in a single converter structure. The proposed DSBPFC SEPIC converter with Totem-Pole method improves PF and reduces THDi and output voltage ripple compared to the conventional FBR SEPIC. Additionally, it only requires three diodes instead of five. The optimization parameter design minimizes the THDi and output voltage ripple. In addition, to improve the quality of the AC source, the inductors are designed to operate in DCM and CCM based on the ripple-balancing concept between input and output inductors. As to reduce output voltage ripple, a high capacitance of output capacitor is used. The simulation result of the THDi is 3.8% whereas the experimental result shows that the THDi is 23.5%; which can be attributed to the parasitic elements at the passive components. Furthermore, the experimental results of the output voltage ripple are 2 V with output capacitance of 3300 μF, compared to the output voltage ripple of 4.40 V for 470 μF. Therefore, the proposed converter's design is confirmed with an output power of approximately 14.4 W.

Selection Method of Capacitor Capacity Considering the Influence of Gap Displacement in Self-excited Rail Brakes

Selection Method of Capacitor Capacity Considering the Influence of Gap Displacement in Self-excited Rail Brakes

ЕКСПЕРИМЕНТАЛЬНІ ДОСЛІДЖЕННЯ БЕЗКОНТАКТНИХ МАГНІТОЕЛЕКТРИЧНИХ ТАХОГЕНЕРАТОРІВ

The paper is devoted to the study of the characteristics and operating modes of a brushless magneto-electric tachogenerator, which is implemented on the basis of a traditional radial electric machine with a slotless stator and permanent magnets on the rotor. Options for generating an DC output signal using diode and transistor rectifiers have been studied. The dependences of the average value of the output signal, the slope of the output signal, the coefficient of deviation of the characteristic from the specified value and the pulsation coefficient were obtained depending on the rotation speed of the rotor shaft. The influence of the capacitance of the filter capacitor on the magnitude of the output signal ripple amplitude has been studied. Ref. 13, fig. 9, table.

Effects of impedance matching network on α-γ mode transition in atmospheric pressure RF discharges

In atmospheric pressure RF discharges, positive and negative feedback regions are defined based on the influence of varying the capacitance of the series capacitor in an inverted L-type impedance matching network on the fed RF power at the input port of the impedance matching network. The impact of the impedance matching network on the α-γ mode transition was investigated by adjusting the tuning series capacitor in the impedance matching network. The critical RF power, as well as the current and voltage at the α-γ mode transition, is almost independent of the impedance matching network, while the counterpart immediately after the α-γ mode transition varies remarkably. The underlying mechanism is understood in terms of different feedbacks. Positive and negative feedbacks respectively promote and suppress the increment in RF power during the α-γ mode transition.

Structure and properties of alloys based on electroerosive brass powder LS58-3 obtained in distilled water

The purpose of this work was to study the microstructure and physico-mechanical properties of alloy blanks based on electroerosive powder brass of the LS58-3 brand obtained in distilled water. Methods. To carry out the planned research, waste of the LS58-3 alloy was selected. Distilled water was used as the working fluid. In an experimental patented installation for producing powders, waste LS58-3 alloy was dispersed in distilled water with a load mass of 300 g. The following modes were used: capacitor capacity 45–65 μF; voltage at the electrodes from 150–200 V; pulse repetition rate 50–100 Hz. The preparation of new alloy blanks was carried out using an SPS 25-10 electric spark plasma sintering installation (ThermalTechnology, USA). The microstructure of new alloy workpieces was studied using an electron-ion scanning (raster) microscope QUANTA 600 FEG (Netherlands). The study of the porosity of workpieces of new alloys was carried out using an optical inverted microscope OLYMPUS GX51 (Japan). The study of microhardness of workpieces of new alloys was carried out using an automated microhardness tester AFFRI DM-8 (Vickers). Results. Analysis of the microstructure showed that the sample has a fine-grained structure and a homogeneous surface. According to the obtained porosity analysis results, the sample has less than 1% pores, which is achieved thanks to the technology of spark plasma sintering of the powder. Analysis of the microhardness of the sample showed a significant increase in microhardness, which is explained by the presence of high-hard particles formed during quenching of metal vapor in the working fluid during dispersion. Conclusion. The use of spark plasma sintering technology for electroerosive brass makes it possible to obtain blanks of new alloys with a practically non-porous structure, which leads to an increase in the hardness of the resulting blanks. The results of the conducted studies make it possible to recommend the use of the resulting powder as a starting material for the production of alloy blanks and to expand the scope of their practical application.

Analysis of Energy During Spark Discharge in Short Circuit of Capacitive Circuit

ABSTRACT In the explosive environments, the electrical sparks with short circuit of capacitor output will ignite the surrounding explosive medium, and the relationship between effective ignition energy, capacitance energy conversion rate, capacitor capacitance and capacitor terminal voltage is unclear. Based on the three stages of breakdown, discharge and attenuation of the discharge characteristic curve of capacitive circuit, this paper deduces the expressions of spark resistance and discharge current including voltage, capacitance and polar distance parameters. Based on the programmable micro-nano gap discharge experimental platform, experiments under different voltages and different capacitances were carried out. It is found that the theoretical voltage-current curve and spark energy conversion rate are in good agreement with the experimental fitting curve and spark energy conversion rate. And with the increase of capacitance or voltage, the peak current and discharge time increase, which leads to the increase of energy. The conversion rate of spark energy decreases with the increase of capacitance or voltage, and the conversion rate changes between 20% and 30%. The change of spark energy conversion rate is also related to spark resistance, and with the decrease of spark resistance, the spark energy conversion rate also decreases. This study can further understand the energy variation in the discharge gap and is of great significance for the research of intrinsically safe circuits.

Gamma‐Ray‐Induced Photoelectric Field Exacerbating Irradiation Damage in Ceramic Capacitors

Ceramic capacitors are widely used in radioactive environments and are known to take irradiation damages, but most of previous studies of its reliability focus on thermal or electrical issues, and much less is known about the microscopic mechanism of its irradiation damaging process. Herein, it is shown that the capacitance of ceramic capacitors can change significantly under continuous gamma‐ray irradiation. Moreover, it is noticed that ex situ measurements will underestimate the effect comparing with the in situ one. Herein, it is discovered that this difference is due to the gamma‐ray‐induced photoelectric field, which dissipate rapidly in ex situ measurements. While the impact of the photoelectric field on the capacitance can be seen in situ, due to the recombination of photogenerated carriers and annealing of defects after irradiation, ex situ measurements only account for a part of the irradiation damage. This discovery indicates that ex situ measurements, which are prevailing in irradiation damage studies, can miss critical information, and in situ measurements are necessary for revealing the mechanism of the process.

Hydrogen-induced tunable remanent polarization in a perovskite nickelate

Materials with field-tunable polarization are of broad interest to condensed matter sciences and solid-state device technologies. Here, using hydrogen (H) donor doping, we modify the room temperature metallic phase of a perovskite nickelate NdNiO3 into an insulating phase with both metastable dipolar polarization and space-charge polarization. We then demonstrate transient negative differential capacitance in thin film capacitors. The space-charge polarization caused by long-range movement and trapping of protons dominates when the electric field exceeds the threshold value. First-principles calculations suggest the polarization originates from the polar structure created by H doping. We find that polarization decays within ~1 second which is an interesting temporal regime for neuromorphic computing hardware design, and we implement the transient characteristics in a neural network to demonstrate unsupervised learning. These discoveries open new avenues for designing ferroelectric materials and electrets using light-ion doping.

СТІЙКІСТЬ РОБОЧИХ РЕЖИМІВ АВТОНОМНИХ АСИНХРОННИХ ГЕНЕРАТОРІВ ІЗ САМОЗБУДЖЕННЯМ

The paper presents the results of investigation the stability conditions of self-excited induction generators. A mathematical model of the generating system with an analytical description of the dependence of the magnetization inductance on the current is used. It allows to avoid the iterative procedure and to scale the dependence to determine the magnetization inductance for induction machines of different types and power. The influence of the load inductance on the stability of the generating system at different rotational speeds is investigated. It is shown that an increase in the inductance value increases the system stability margins in the self-excitation zone. Also this article deals with the issues of system stability within the self-excitation zone of an induction generator at different rotational speeds depending on the value of the capacitance of self-excitation capacitors. It is depicted that at low rotational speeds there may not exist a stable operation mode in the self-excitation zone regardless of the value of the capacitance in the motor stator circuit. This method of determination the stability of the operation modes of the generation system will be useful both for the design of new systems and for the modification and adjustment of existing ones. References 9, figures 4.

Electronically Tunable Grounded and Floating Capacitance Multipliers Using a Single Active Element

A capacitance multiplier is an active circuit designed specifically to increase the capacitance of a passive capacitor to a significantly higher capacitance level. In this paper, the use of a voltage differencing differential difference amplifier (VDDDA), an electronically controllable active device for designing grounded and floating capacitance multipliers, is proposed. The capacitance multipliers proposed in this study are extremely simple and consist of a VDDDA, a resistor, and a capacitor. The multiplication factor (Kc) can be electronically controlled by adjusting the external bias current (IB). It offers an easy way of controlling it by utilizing a microcontroller for modern analog signal processing systems. The multiplication factor has the potential to be adjusted to a value that is either less than or greater than one, hence widening the variety of uses. The grounded capacitance multiplier can be easily transformed into a floating one by utilizing Zc-VDDDA. PSpice simulation and experimentation with a VDDDA realized from commercially available integrated circuits were used to test the performance of the proposed capacitance multipliers. The multiplication factor is electronically adjustable, ranging in approximation from 0.56 to 13.94. The operating frequency range is approximately three frequency decades. The realization of the lagging and leading phase shifters using the proposed capacitance multiplier is also examined and proven. The results reveal that the lagging and leading phase shifts are electronically tuned via the multiplication factor of the proposed capacitance multipliers.

Ultra‐High Energy Density in Cyanoethyl Biomass Polymers

AbstractDielectric polymers are essential to capacitive capacitors widely used in modern electronic and electrical systems. Most useful dielectric polymers are derived from petroleum while environmentally sustainable dielectric biomass remains mostly unexplored although they are abundant, renewable, and cost‐effective. Here an ultrahigh energy density in cyanoethyl cellulose (CEC) and cyanoethyl pullulan (CEP) obtained by replacing the hydroxyl groups of cellulose and pullulan with cyanoethyl is reported. Large dielectric constants of 16.7 and 20.0 in CEC and CEP due to the strong polarity of cyanoethyl which are comparable to high‐dielectric ferroelectric polymers are shown. CEC and CEP show nearly no degradation of the dielectric constant with increasing electric fields, inhabiting the early polarization saturation and thus leading to improved energy density, which is different from relaxor ferroelectric polymers. Consequently, solution‐processable CEP films exhibit an ultrahigh discharged energy density of 28.2 J cm−3 with an efficiency of 72% at 600 MV m−1, outperforming other all‐organic dielectric biomass materials. The work paves the way for the development of high‐performance dielectric biomass for energy storage applications.

Synergizing Battery-Powered Permanent Magnet Synchronous Motor Control with Integrated Modular Multilevel Converter Systems

This proposed work presents a comprehensive examination of a modular multilevel converter (MMC) combined with a permanent magnet synchronous motor (PMSM) for battery energy management in applications. In order to provide effective energy transfer and dynamic control, the Modular Multilevel Converter serves as a bridge between the battery system and the Permanent Magnet Synchronous Motor drive. By cleverly controlling energy flow and minimizing losses during charging and discharging cycles, the combination of MMC with PMSM seeks to increase energy efficiency and prolong battery life. Since the energy source provides all of the power for the motor, it runs at a constant pace. When the accelerating mode finishes, the energy storage receives just enough power to maintain a steady voltage. The energy storage system utilizes the majority of the renewable power generated by the electric motor when it is in deceleration mode to raise the voltage in the system. During the subsequent acceleration mode, the stored energy might be released the MMC-BESS, which combines a modular multilevel converter with a battery energy storage system, is gaining popularity due to its high adaptability and dependability. This system integrates batteries into a sub module. Sub-modular capacitor voltage fluctuations are caused by the significant reactive power that is generated through the workings of modular multilevel converters. To reduce the fluctuation, large capacitance capacitors is required, which would significantly increase the system's capacity. The proposed approach means to upgrade energy proficiency and execution in electric vehicle applications. By joining the benefits of battery power with the flexibility of MMC frameworks, the arrangement offers upgraded control accuracy, decreased misfortunes, and further developed adaptation to non-critical failure. This combination works with consistent power the executives, guaranteeing ideal use of assets while meeting severe execution prerequisites. Through exhaustive examination and recreation, the adequacy of this incorporated framework is illustrated, displaying propelling the field of electric vehicle impetus and power conversion potential.

Influence of Load Models and DG Operational Power Factor on Optimization of Shunt Capacitor Placement in Distribution Grids Considering Voltage Stability

The paper proposes a mathematical model of mixed-integer nonlinear programming (MINLP) to optimize the location and size of shunt capacitors in power distribution grids with distributed generation (DG), considering voltage stability constraints. At the same time, the paper also analyzes the influence of the load models, such as voltage-dependence load (ZIP load) and constant power load, together with DG’s operating power factor on the optimal solution. The objective function of the proposed optimization formulation is minimizing the total expenses, including the capital investment of capacitors and the expense incurred by network energy loss. This MINLP model includes constraints in the current and critical loading conditions, such as the system of power flow equations, nodal voltage limits, branch thermal limits, capacitor-related constraints, and restrictions of minimum security level. The proposed optimization model was evaluated on a modified IEEE 33-node distribution grid using the KNITRO commercial solver with the GAMS programming language. The calculation results show that the voltage stability constraints, load models, and operational power factor of the DG units have an essential influence on the optimal position and capacity of the shunt capacitors.

Study of Start-up and Shutdown Modes of an Asynchronous Electric Drive for a Centrifugal Pump

The aim of this study is to investigate the commutation processes of an asynchronous short-circuited electric drive for a centrifugal pump. The set goal is achieved by solving two tasks: analyzing the dynamic modes of connection to and disconnection from the network of the asynchronous motor of the centrifugal pump for a given power supply scheme; assessing the qualitative and quantitative indicators of the transient processes of the electric drive. Among the most significant results of the study, it is possible to highlight the ability to form practical recommendations on the operation peculiarities of electric drives for a wide class of mechanisms. The conducted research allowed asserting that in an electrical system with capacitors directly connected to the stator winding and during both the connection and disconnection of the drive motor of the centrifugal pump, voltages significantly exceeding the nominal ones may occur. It has been determined that considering the harsh operating conditions of pump units, such overvoltages represent a danger to the motor winding insulation. During the motor disconnection, significant overvoltages on the stator windings are possible if, for any reason, the capacitor's capacitance exceeds the calculated base value for the applied motor. The practical significance of the obtained results lies in the fact that the assumption of the motor transitioning to intensive braking mode and subsequent hydraulic shock upon disconnection from the network due to self-excitation did not prove to be true. The electric drive provides braking under the action of the load torque without mechanical overloads.

Determination of the capacitance of capacitor with orthotropic dielectric material

AbstractThe paper deals with the capacitance of cylindrical two-dimensional capacitor which consists of Cartesian orthotropic dielectric material. The determination of the capacitance of capacitor with orthotropic dielectric material by a suitable coordinate transformation is reduced to the computation of capacitance of an isotropic capacitor. It is proven that the capacitance of a Cartesian orthotropic capacitor can be obtained in terms of an isotropic capacitor whose dielectric constant is the geometric mean of the dielectric constant of the orthotropic capacitor.