Thousands Of Volts Research Articles

Actuators for Large Wind Energy Systems—A Tutorial-Focused Survey

Undoubtedly, wind turbines are currently one of the most significant contributors to clean energy. Therefore, it is crucial to enhance the capability of wind turbines, which in turn leads to an increase in their dimensions. Nevertheless, only advanced control systems can guarantee the optimal and secure operation of these huge machines. On the other hand, the precise control of these modern wind turbines is only achievable through the use of highly specialised actuators. Despite their importance, actuators have historically been overlooked and seen as secondary components in control systems. However, in modern machines, actuators are required to manipulate multiple tonnes or manage thousands of volts and amperes within short times. Consequently, greater emphasis must be placed on their handling and operation. This study aims to review actuators for modern large wind energy converters from a control engineering perspective, using a tutorial approach.

Deconvolution-based correction of pre-strike arc voltage measurement in medium voltage switches

Abstract Switching arc characterization, e.g. measuring the arc voltage and current, is crucial for assessing the performance of power switchgears under different working conditions. This is especially challenging for short circuit current making as one of the most severe operations for medium voltage load break switches. By closing the switch, a short circuit current flows through the arc which is ignited by the electrical breakdown in the gap between contacts before the contacts touch. This results in an abrupt change from the rated voltage of the power network, i.e. tens of thousands of volts, to the switching arc voltage, i.e. a few tens of volts and ultimately zero when the contacts touch. The inherent response of the measurement system to this very large step preceding the arc formation overlaps with the switching arc voltage and results in unrealistic arc voltages which makes correction of the distorted voltage waveform necessary. In this paper, a post processing method based on deconvolution correction technique, i.e. deconvolution of the measured voltage in time and frequency domains, is examined using experimentally determined impulse responses of the measurement system. To demonstrate its effectiveness, this method is applied to three different measurement system configurations with various step responses. The results show practically identical deconvoluted (corrected) voltage waveforms in all three measurement systems, although the directly measured waveforms have significant differences. The corrected arc voltage waveforms are in agreement with the indirect measurements proposed in previous studies.

Ultralow electric-field poling of LiNbO3 single-crystal devices

The LiNbO3 (LNO) single crystal receives wide applications in nonvolatile memories, surface acoustic wave devices, and electro-optic modulators. However, engineering of antiparallel domain patterns within micrometer-sized devices generally requires a poling voltage more than a few thousands of volts. The high poling voltage could invoke dielectric breakdown. Here, we found an effective method to increase the local electric field significantly for domain nucleation at the interfaces of an etched LNO mesa in contact to two concave side electrodes, while the electric field across the protruding intra-electrode area can be lower by 10 times after the metal diffusion at the surface. Subsequent piezoresponse force microscopy mapping shows the nucleating domains to grow up through the entire intra-electrode area. This method is universal and analogous to other ferroelectric devices for the realization of low-voltage operations.

A Review and Comprehensive Study on DC-DC Converters

Background: DC-DC converters are used in various applications based on their required voltage capabilities ranging from milli volts to thousands of volts. Methods: This review paper discusses various voltage boosting techniques, such as buck-boost, switched inductor, switched capacitors, isolated converters, etc., and provides a detailed evaluation of the literature and comparison of different DC-DC converters. Results: This study reports a number of storage elements included, such as inductors and capacitors as well as switches and diodes. Their features along with methodologies, merits, complexity, efficiency, and voltage gain have been tabulated. A comprehensive study, converter classification based on the characteristics, and a detailed analysis of isolated and non-isolated DC-DC converters have also been provided. Conclusion: As this study provides a comparison of each isolated and non-isolated converter's comprehensive gain, this research may help in future topology optimization for the choice of the ideal converter for applications. In addition, the examination of each isolated and non-isolated converter's comprehensive gain comparison has also been presented in this paper.

MCU-based Safer Coagulation Mode by Nonfixed Duty Cycle for an Electrosurgery Inverter.

The arcing-involved pulsating coagulation mode with both active and blank periods is essential for modern electrosurgery. This paper begins with a comprehensive introduction to such a pulsating mode, followed by its implementation challenges. Then, an industrial-scale low-speed microcontroller unit (MCU), TMS320F28379D, is utilized to exemplify the proposed output sampling and data-transferring strategy on a gallium nitride (GaN)-based high-frequency inverter that enables coagulation mode with interweaved active periods and blank periods. The inverter prototype fills the active period with 390 kHz sinusoids of amplitude ranging from hundreds to thousands of Volts, while maintaining null outputs during blank periods. The strategy of sampling the above-mentioned sinusoidal outputs, coupled with their data transfer facilitated by direct memory access (DMA), is also articulated for subsequential power computation. Besides that, a novel nonfixed duty cycle approach, featuring an alterable number of sinusoids as the active period, is proposed and integrated into the GaN-based inverter to enhance mode safety. Finally, the power tracking performance of the mode is evaluated initially on resistive load, secondarily on resistive plus capacitive load (R-C), and thirdly on fresh biotissue with the appearance of electrical arcing. The existing necessity of the null blank periods is examined at the end of the paper.

High-Precision Measurements of 44Ca/40Ca Using Multiple-Collector Inductively Coupled Plasma Mass Spectrometry without Collision-Cell Technology.

Herein, we present a new method for determining the Ca isotopic composition of geological samples. To eliminate matrix elements from Ca, a column chromatography method was developed using a N,N,N'N' tetraoctyl-1,5-diglycolamide (TODGA) resin. The Ca isotopic compositions were measured by a multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) without collision cell equipment, especially that direct measurement to 44Ca/40Ca can be achieved. To mitigate the interference from 40Ar during 40Ca measurement, the cold plasma technique was used to suppress the Ar+ generation, resulting in a background Ar+ intensity of <300 mV, in contrast to the conventional hot plasma conditions, which typically yield thousands of volts for Ar+ intensities. Given the potential for a concentration mismatch between the sample and bracketed standard solutions to cause an intensive shift in measured Ca isotopic compositions, a correction for the [Ca] match is needed. To avoid matrix effects arising from residue matrix elements, it is crucial to limit the concentrations below 1% of Ca for most matrix elements (including Al, Mg, K, Na, and Sr) and below 1‰ for Fe. Notably, the tolerance of residue Sr is effectively improved compared to measurements with CC-MC-ICP-MS and traditional Hot-plasma-SSB-MC-ICP-MS methods with the conventional hot plasma technique, thereby lowering the complexity of column chemistry. The measured δ44/40Ca, δ44/42Ca, and ε40Ca values for eight reference materials agree well with previously reported values within analytical uncertainties. This method demonstrates long-term precision is better than 0.10‰ (two standard deviations) for both δ values (i.e., δ44/40Ca and δ44/42Ca). We anticipate that the proposed method will benefit the growth of the Ca isotope data set and foster an increase in the application of Ca isotope in Earth science studies.

Dynamic evolution investigation on the dielectric surface charging under electron irradiation with various energy distributions

Spacecrafts face various environmental risks in their working durations, thereinto, surface charging, which may result in abnormal operation of devices, is a typical detrimental effect and deserves to be deeply investigated, especially the charging process under various electron energy distributions. In this work, aiming to reveal the evolution process of surface charging in detail, we establish an approach for predicting surface potential under electron irradiation by considering the electron emission process. Mathematical relationships for the dependence of surface charging on the secondary electron yield properties of dielectric surfaces are established. The dynamic process of surface potential evolution is calculated for MgO and Al2O3 when the energy variation of incident electrons obeys uniform distribution, Gaussian distribution, and Maxwell distribution. By analyzing the dynamic equilibrium process of electron incidence/exit in the positively/negatively charged cases, the effect of electron energy on equilibrium surface potential and equilibrium time are quantitatively calculated. It is found that the surface potential will be a dozen volts when the surface is positively charged, surface charging of this magnitude does not have a noticeable effect, and the equilibrium time is short (several microseconds). However, the surface potential may reach very high levels (thousands of volts) leading to breakdowns when the dielectric surface is negatively charged, and its equilibrium time is 3 to 4 orders of magnitude higher than the positively charged case. Via calculating the surface potential under various incident distributions, we acquire the dynamic evolution process of surface potential evolution under different energy distributions, and find its consequence shows a similar tendency for the situation of constant energy irradiation. This work digs into the mechanism of surface charging under various irradiation situations, which makes sense for further works involving surface charging induced by electron irradiation with multiple energy distributions.

Static electricity passively attracts ticks onto hosts.

Most terrestrial animals naturally accumulate electrostatic charges, meaning that they will generate electric forces that interact with other charges in their environment, including those on or within other organisms. However, how this naturally occurring static electricity influences the ecology and life history of organisms remains largely unknown.1 Mammals, birds, and reptiles are known to carry appreciable net electrostatic charges, equivalent to surface potentials on the order of hundreds to tens of thousands of volts.1,2,3,4,5,6,7 Therefore, we hypothesize that their parasites, such as ticks, are passively attracted onto their surfaces by electrostatic forces acting across air gaps. This biophysical mechanism is proposed by us to assist these ectoparasites in making contact with their hosts, increasing their effective "reach" because they are otherwise incapable of jumping. Herein, experimental and theoretical evidence show that the tick Ixodes ricinus (Figure1A) can close the gap to their hosts using ecologically relevant electric fields. We also find that this electrostatic interaction is not significantly influenced by the polarity of the electric field, revealing that the mechanism of attraction relies upon induction of an electrical polarization within the tick, as opposed to a static charge on its surface. These findings open a new dimension to our understanding of how ticks, and possibly many other terrestrial organisms, find and attach to their hosts or vectors. Furthermore, this discovery may inspire novel solutions for mitigating the notable and often devastating economic, social, and public health impacts of ticks on humans and livestock.8,9,10,11,12,13,14,15.

Electrical Interference Simulation and Prediction Model for Acoustoelectric Logging Detector.

Acoustic logging instruments generate high voltages in the order of thousands of volts. Electrical interferences are thus induced by high-voltage pulses that affect the logging tool and make it inoperable owing to damaged components in severe cases. High-voltage pulses from the acoustoelectric logging detector interfere with the electrode measurement loop through capacitive coupling, which has seriously affected the acoustoelectric signal measurements. In this paper, we simulate high voltage pulses, capacitive coupling and electrode measurement loops based on qualitative analysis of the causes of electrical interference. Based on the structure of the acoustoelectric logging detector and the logging environment, an electrical interference simulation and prediction model was developed to quantify the characteristics of the electrical interference signal.

Contact Electrification Behaviors of Solid–Liquid Interface: Regulation, Mechanisms, and Applications

Liquid–solid contact electrification is a universal physical phenomenon. The electrical energy produced by a drop of water during the solid–liquid triboelectric electrification (TE) process is negligible, usually at the level of nA or uA. However, by adjusting the structure and composition of materials, or by designing devices more rationally, TE of a drop of water can reach voltages in the thousands of volts and currents in the mA level, which is sufficient to power many electronic devices. Therefore, studying solid–liquid triboelectric nanogenerators is of great significance in the field of energy harvesting. To achieve the manipulation of liquid–solid triboelectrification to nurture strengths and bypass weaknesses, a thorough knowledge of the liquid–solid contact electrification process and its influencing elements is required. The concept, influencing variables, mechanisms, and current control tactics of solid–liquid triboelectrification are addressed in this review. Then, using triboelectric generator technology, solid friction layers are designed and fabricated from three perspectives: structure design, surface functionalization modification, and interface wettability control, with discussion of how the three factors interact and contribute to solid–liquid electrification behavior. How solid–liquid triboelectrification can be used to capture energy and create self‐powered sensors is discussed.

Multifunctional Microelectrode for Low-Voltage Pulsed Field Ablation in Atrial Fibrillation

Pulsed field ablation is an emerging technique for the treatment of atrial fibrillation, and it can specifically damage cardiomyocytes without destroying surrounding tissues. However, current single-function ablation electrodes apply electric pulses at thousands of volts, which is potentially harmful to the heart. In this letter, we propose a multifunctional microelectrode for low-voltage pulsed field ablation and effect evaluation. By using finite element analysis and tests on potato tissues and in vivo experiments, we show that the soft microelectrode in multiplexed array format supports two orders of magnitude reduction in ablation voltage compared with the state of the art. Meanwhile, the electrode-tissue equivalent circuit before and after irreversible electroporation is established, and we find that the ablation effect could be evaluated by impedance. In the future, the microelectrode integrated with a medical balloon can be applied to minimally invasive surgery for improving the success rate of pulsed field ablation.

Untethered Microrobots Driven by kV-Level Capacitive Actuators via Mechanical Electrostatic Inverters

Several microrobots driven by capacitive actuators have shown excellent performance because of the high power density and low working current of the actuators. However, these capacitive actuators need high alternating working voltage (hundreds or thousands of volts), which results in heavy and bulky inverter circuits and increases the difficulty of achieving untethered movements for microrobots. In this work, we report a novel and lightweight mechanical electrostatic inverter based on the self-excited electrostatic vibration for untethered crawling microrobots driven by piezoelectric actuators (working under 300 volts) and dielectric elastomer actuators (working under 3600 volts), respectively. The electrostatic inverter, consisting of just two electrodes and a conductive cantilever, is integrated into the body of the microrobots to generate a high alternating voltage from 200 to 10000 volts, and its weight is in milligram scale (16.2 mg--96.7 mg). Powered by onboard capacitors, two untethered microrobots worked continuously for 3 s--6 s and moved at a maximum speed of 18--41 mm/s. The work provides another scheme for designing untethered microrobots driven by capacitive actuators with high working voltage up to thousands of volts.

A High-Gain DC Side Converter with a Ripple-Free Input Current for Offshore Wind Energy Systems

Considering that the distance between offshore wind farms and onshore converters is getting farther and farther, dc transmission becomes increasingly more applicable than conventional ac transmission. To reduce the transmission loss, a feasible solution is using a high-gain dc/dc converter to boost the rectified output voltage to thousands of volts. Thus, a novel single-switch high-gain dc/dc converter with a ripple-free input current is presented in this paper. The structure consists of two cells—a coupled-inductor cell and a switched-capacitor cell. The coupled-inductor cell in the proposed converter provides a ripple-free input current. The switched-capacitor cell provides a high voltage gain. The converter has a simple control strategy due to the use of a single switch. Moreover, the output capacitor is charged and discharged continuously by a 180° phase shift to eliminate the output voltage ripple. A steady-state analysis of the converter is proposed to determine the parameters of the devices. In addition, a 240 W, 40/308 V laboratory prototype at 35 kHz switching frequency has been developed, in which the input current ripple is only 1.1% and a peak efficiency of 94.5% is reached. The experimental results verify the validity and feasibility of the proposed topology.

Quadcopter Vehicle Proportional-Integral-Derivative Controller (PIDC) Tuning by Particle-Swarm Optimization (PSO)

Inspection of the faults and damages in high voltage transmission lines is not only unsafe and costly but also a very time-consuming process. In addition, it demands highly skilled manpower for the operation at tens of meters above the ground on cables carrying thousands of Volts. Meanwhile, the Quadcopter Aerial Vehicle (QAV) system became a popular alternative for aerial photography applications due to its low cost, ease of usage, and fast response wherein the proportional-integral-derivative controller (PIDC) is used. The PID controller compares the expected location of the drone with the actual measured position thereby can accurately detect the faults in the transmission lines. Based on these factors, in this study, the flight simulation is done according to the desired flight path, and drone imagery is used for (insulator, power line, and porcelain) flaw identification. Furthermore, three movements (roll, pitch, and yaw) of the quadcopter were controlled by different PIDC that were optimized using the particle swarm optimization (PSO). The MATLAB/Simulink application was used to develop the system and simulate the results (R2021b). This clearly suggested that the quadcopter continues to fly on a trajectory with minimum inaccuracy, wherein the PIDC operated as a closed-loop adaptive controller. Finally, the PSO-PIDC outperformed the PIDC due to the critical nature of manual gain modification for quadcopter flight stability.

Achieving ultrahigh instantaneous power density of 10\u2009MW/m2 by leveraging the opposite-charge-enhanced transistor-like triboelectric nanogenerator (OCT-TENG)

Converting various types of ambient mechanical energy into electricity, triboelectric nanogenerator (TENG) has attracted worldwide attention. Despite its ability to reach high open-circuit voltage up to thousands of volts, the power output of TENG is usually meager due to the high output impedance and low charge transfer. Here, leveraging the opposite-charge-enhancement effect and the transistor-like device design, we circumvent these limitations and develop a TENG that is capable of delivering instantaneous power density over 10 MW/m2 at a low frequency of ~ 1 Hz, far beyond that of the previous reports. With such high-power output, 180 W commercial lamps can be lighted by a TENG device. A vehicle bulb containing LEDs rated 30 W is also wirelessly powered and able to illuminate objects further than 0.9 meters away. Our results not only set a record of the high-power output of TENG but also pave the avenues for using TENG to power the broad practical electrical appliances.

Ultra-High-Voltage (7-kV) Bidirectional Flyback Converter Used to Drive Capacitive Actuators

Dielectric elastomer actuators (DEAs) have extremely advantageous characteristics such as lightness, compactness, flexibility, and large displacements. However, in order to operate, they can require voltages in the order of several thousands of volts. Thus, to unleash the full potential of DEAs, it becomes essential to be able to generate and manipulate such voltages with an electronics as compact and efficient as possible. While previous works showed that it was possible to implement a system capable of supplying voltages of up to 2.5 kV and recovering part of the energy stored in DEAs (due to their capacitive nature), no work managed to go over that threshold for two main reasons: first, due to the absence of switches capable of withstanding more than 4.5 kV, and, second, due to parasitic capacitances of the flyback's coupled inductor, which steal an increasingly large part of the energy destined for the load when the output voltage is higher. This article, therefore, proposes a global design, where the factors limiting the increase in the output voltage have been mastered. Through a careful design of the coupled inductor combined with the use of mosfets put in series, thanks to the pulsed transformer gate drive topology to handle the high voltages, this work goes beyond the current state of the art. Indeed, here, we present various strategies undertaken, which led to the manufacture of a bidirectional flyback converter capable of amplifying an input voltage of 12 V to more than 7 kV across a capacitive load and recuperating parts of the energy stored. A preliminary study of the efficiency shows an approximate 58% efficiency during the charge phase from 0 V to 7 kV and a 54% efficiency during the discharge phase.

A Review on Small Power Rating PV Inverter Topologies and Smart PV Inverters

The two most critical deciding factors for power consumption are energy efficiency and cost. Power electronic circuits are widely used and play an important role in achieving high efficiency in power distribution to customers and power transfer from source to load. Furthermore, solar energy is abundant, sustainable, and pollution-free in nature. Power electronic circuits are used in high-power applications with voltages ranging from a few millivolts to thousands of volts and wattages ranging from a few mW to megawatts. This paper examines a variety of inverter topologies and their modeling, as well as a comparison of single-stage and multi-stage/inverter topologies depending on the application. The main aim of control techniques is to keep Total Harmonic Distortion (THD) to a minimum and the switching frequency within the permissible range so that inverters for renewable energy sources, electric vehicles, uninterruptible power supply (UPS) systems, and hybrid energy storage systems can work efficiently. Plug-and-play, adaptability, self-awareness, and other features should all be included in a smart inverter. Based on the findings of this comparative analysis, selection criteria are established. This comparative analysis can be used to develop selection criteria for choosing inverter circuits for the various applications described in this paper.

Effect of Simulated GEO Environment on the Properties of Solar Panel Coverglasses

The harsh space environment at geosynchronous orbit (GEO) induces differential charging of spacecraft surfaces due to simultaneous fluxes of electrons with a wide distribution of energies onto, into, and through spacecraft surface materials. Thus, satellite surfaces can charge thousands of volts with respect to each other, whereas entire satellites can charge tens of thousands of volts negative relative to their surrounding space plasma. The ensuing electric fields can cause local discharges (arcs) from one part of the spacecraft to another, endangering the normal operation of the satellite. Furthermore, solar cell coverglass contamination induced by the high rate of arcing is sufficient to produce the ~1.5%/year power loss in excess of radiation damage that has been observed on global positioning system (GPS) satellites. This work focuses on evaluation of a GEO space weather effect on material properties caused by irradiating different types of commonly used space solar cell coverglasses (CMX, fused silica, and Corning 0214) with >90-keV electron radiation.

The Supercharged Semiconductor: Gallium oxide could make powerful radios and switch thousands of volts

In the May 2002 Issue of this Magazine, the Late Lester F. Eastman and Umesh K. Mishra made the case for what was then a long-shot technology in the world of power semiconductors: gallium nitride (GaN). They presented an optimistic outlook for powerful, rugged radio-frequency amplifiers in the then-nascent broadband wireless networks and in radar, as well as in power-switching applications for the electric grid. They called GaN devices “the toughest transistor yet.”

ВИСОКОЛІНІЙНІ БАЛАНСНІ ДВОТАКТНІ ПІДСИЛЮВАЧІ ПОСТІЙНОГО СТРУМУ ІЗ НИЗКОЮ ПОХИБКОЮ ЗСУВУ НУЛЯ

It is known that push-pull DC amplifiers (PPDA), as a rule, have a high linearity of the transfer characteristic, a wide passband (hundreds of MHz and GHz units) at the level of unity gain, and a significant rate of change in the output voltage (at least thousands of volts per microsecond). Serial models of such integrated PPDA are produced by Analog Devices, Texas Instruments, Linear Technology, National Semiconductor and others. Due to the presence of these characteristics, PPDA are widely used in current-voltage, current-current, ADC, DAC, direct digital synthesis systems and multi-channel digital systems for processing and recording analog signals. Despite the high indicated static and dynamic characteristics of the PPDAs built on bipolar transistors, which have a significant additive error in the form of an input zero bias current of hundreds of nA and μA units. Often this can degrade the static parameters of these devices and systems. When the input zero bias current appears, there are basic currents of bipolar transistors in the input stages of the amplifiers. To reduce their influence in single-cycle current amplifiers, some special circuit methods are used. Which allow an order of magnitude to reduce the input zero bias current of the differential stage without affecting the bias voltage or speed. To reduce the input zero bias current in the PPDA, it was proposed to apply basic current compensation in the input stages, as well as to build the input stages on Shiklai composite transistors, which will significantly improve the accuracy of the circuit as a whole.