Voltage Conditions Research Articles

Research on the Influence of Magnetic Field Assistance on the Quality of an Electro-Spark Deposition Layer

Aimed at solving the problems of single control measures in the electro-spark deposition (ESD) process, difficulty controlling the micro-process using heterogeneous materials (for the electrode and matrix), and the unstable quality and reliability of repairs to the deposition layer, a method of magnetic-field-assistance electro-spark deposition (MFESD) was proposed. An MFESD device was built, and a Ni electrode was used for deposition on the surface of 45 steel under the conditions of deposition voltages of 30 V, 60 V, and 90 V, respectively. This study examined the impact of the magnetic field’s intensity and frequency on the microstructure and mechanical properties of electro-spark deposition layers. The results show that the sputtering and protrusion of the electrode material on the surface of the deposition layer gradually decrease with an increase in the magnetic field’s intensity and frequency, defects such as pores and cracks are obviously improved, and the structure is uninterrupted and compact. The surface roughness of the deposited layer decreases with an increase in the magnetic field’s intensity and frequency, and its surface roughness decreases by 44.3%. The cross-section effect of the deposited layer is improved. The thickness of the deposited layer increases with an increase in the magnetic field’s intensity and frequency; the thickness of the deposited layer increases by 13.39%, and its maximum thickness can reach 54.396 μm. At the same time, the microhardness of the deposited layer increases with an increase in the two aforementioned properties of the magnetic field, and its hardness increases by 5.32%. Using a magnetic field to control ESD can effectively control the microscopic process of deposition and obtain high-quality deposition coatings, which have important significance in the surface remanufacturing of key components of high-end equipment.

Radiation‐Tolerant SRAM for Satellite Image Compression Systems: A Hybrid Memory Array Approach

ABSTRACTThis work is based on the design of an SRAM memory array for on board satellite image compression systems, including memory size, cost, power efficiency, and vulnerability to single event upsets (SEU). Initially, we designed a memory cell, RH_14T, specifically to mitigate the impact of SEUs. Subsequently, we incorporated RH_14T into the on‐board memory array in two variations: RH_14T with minimal area overhead (RH_14T_small) and RH_14T with substantial area overhead (RH_14T_large), which have critical charges of 30.10 and 38.77 fC, respectively. Given the higher sensitivity of higher order bits compared to lower order bits in image pixels, RH_14T_small was allocated for the least significant bit (LSB) positions. RH_14_large, on the other hand, was used for the most significant bit (MSB) positions within the memory array. This configuration enhanced the array's overall area, power, and space radiation tolerance. Furthermore, the RH_14T model was bench marked against other recently introduced radiation‐hardened SRAM cells and compared proposed RH_14T CC18T, RHC14T, RHMC12T, SARP12T, SRRD12T, DICE, and QUCCE12T across several critical design parameters. Notably, RH_14T's sensitive nodes can recover their original data even after radiation‐induced value flips. In addition to these benefits, RH_14T also demonstrates a high static voltage noise margin and reduced read and write delays compared to most of the cells it was compared with.

Feasibility exploration of nano-thermal rod applied to deicing of tunnel pavement in cold region

This study investigates the feasibility of using nano-thermal rod for deicing tunnel pavements in cold region. The heating performance of the nano-thermal rod was compared with that of carbon fiber heating wire under low voltage conditions. Experimental studies were conducted in a controlled environmental chamber to evaluate the effects of arrangement parameters (spacing, buried depth, input power) and environmental factors (ambient temperature and moisture) on heating rate and effectiveness. Results show that the nano-thermal rod achieves a working temperature of 60℃ at 3.9 V, with higher heating efficiency than carbon fiber heating wire. Input power and ambient temperature were found to have the greatest influence on heating performance. Surface moisture was shown to adversely affect deicing. The experimental results, verified through COMSOL Multiphysics simulations, demonstrated an error of less than 1.45℃. The findings confirm the feasibility of using nano-thermal rod for efficient deicing of tunnel pavements in cold region.

Analytical Photoresponses of Schottky‐Contact MoS2 Phototransistors

AbstractHigh‐gain photodetectors based on 2D semiconductors have been extensively investigated in the past decades. However, the underlying mechanism remains in dispute without a proper analytical theory. On one side, the classical photogain theory is not applicable, as it was derived on two misplaced assumptions. On the other side, unexpected potential barriers usually present in 2D semi‐conductors but their effect on the ultrahigh gain has been largely ignored. In this work, we first established a universal I‐V equation for Schottky‐contact MoS2 phototransistors, modeled with two anti‐symmetric Schottky diodes and a channel resistor in series. It has been proved to be valid under varying conditions of gate voltage, temperature, light illumination and bias voltage. Moreover, we established analytical equations for photocurrent and gain, which clearly shows that ultrahigh gain is created by light‐induced modulation of potential barrier in exponential form. Finally, the theory was validated on 40 samples by verifying the I–V characteristics and minority carrier lifetime. Our results not only shed light on the working mechanism of 2D phototransistors, but also present important advance for device modeling and design in 2D integrated circuits.

An Adaptive Photosensitivity Pixel for Synchronous Spiking Sensor

ABSTRACTThis paper introduces a novel spiking pixel based on the synchronous readout operation. This design achieves pixel adaptation sensitivity to light, effectively overcoming a fundamental challenge of conventional pixels. It is achieved by assessing the trigger interval, which is the number of frame periods required for two successive pulses in the pixel's output, and dynamically adjusting the reference voltage. Combined with this technique, this novel spiking pixel can enhance sensitivity under low illumination conditions; simultaneously, it seeks to reduce trigger frequency in high‐light conditions. Analysis of the proposed pixel reveals that it extends dynamic range and reduce the impact of the average relative error, representing a notable improvement over existing traditional pixel designs. When the ratio between the two integration voltage ranges of the proposed pixel is 9, the dynamic range can be extended by 18.26 dB. With integration voltage ranges of 300 and 900 mV, the mean average relative error of the proposed pixel is 0.1261 under varying Process, Voltage, and Temperature conditions, demonstrating superior performance compared to the traditional pixels.

Reliability assessment of the thyristor module of high-voltage hybrid switchgears in reservation conditions

In the article, the authors proposed a methodology for evaluating the main indicators of the operational reliability of a high-voltage thyristor module, which is an element of electric power equipment, using the example of the design of such electrical devices as hybrid switches and converters in the structure of traction substations, power supply systems of metallurgical complexes, etc. The proposed method makes it possible to estimate the prob-ability of failure-free operation of the real design of the thyristor module, taking into account its design and implementation scheme, as well as the level and depth of redundancy of the semiconductor devices included in it. As initial data, the proposed method involves the use of electrical load parameters in terms of voltage and current and their redistribution as the reserve resource is exhausted, taking into account the design features of both the electrical device itself and the power supply network where it is located. is established. The proposed method makes it possible to evaluate the effectiveness of the influence of design factors (the number of semiconductor devices, the principle and depth of redundancy, the economic component, etc.) on the main indicators of the operational reliability of the corresponding types of high-voltage equipment, taking into account the electrical load and its changes. The proposed method was tested on the example of a real scheme of the thyristor module of the on-load tap-changer switching device, which was in industrial operation for a long time in the most unfavourable conditions in the power supply structure of the metallurgical industry, where there is high switching frequency, load fluctuations, etc. The implementation of this technique in the conditions of designing high-voltage switching and converting electrical equipment, as well as its operation in the power supply structure, allows to evaluate the influence of the structural features of the semiconductor part, taking into account the load mode, as well as the influence of external and operational factors. A more accurate determination of the effectiveness of the proposed methodology for predicting operational reliability indicators depending on the mode and depth of the load and the type of backup system can be achieved by conducting an additional series of experimental tests on the choice of the type of theoretical system. distribution law and determination of its parameters for specific designs of electrical devices. Thus, a conclusion was made about the possibility of using the obtained results to evaluate the parameters of the operational reliability of the above-mentioned high-voltage equipment, which is used as part of switchgear and power supply systems in both high and low voltage conditions.

Coordination Regulation Enabling Deep Eutectic Electrolyte for Fast-Charging High-Voltage Lithium Metal Batteries.

The safety and cycle stability of lithium metal batteries (LMBs) under conditions of high cut-off voltage and fast charging put forward higher requirements for electrolytes. Here, a sulfonate-based deep eutectic electrolyte (DEE) resulting from the eutectic effect between solid sultone and lithium bis(trifluoromethanesulfonyl)imide without any other additives is reported. The intermolecular coordination effect triggers this eutectic phenomenon, as evidenced with nuclear magnetic resonance, and thus the electrochemical behavior of the DEE can be controlled by jointly regulating the coordination effects of F···H and Li···O intermolecular interactions. The DEE with a properly coordinated environment of Li+ presents a low motion barrier and a high transport rate of localized Li+, leading to a 10 C fast-charging LiFePO4||Li battery with a capacity retention of 95.1% after 500 cycles. Meanwhile, the strengthened α-H···F coordination broadens the electrochemical stability window of the DEE, thus enabling the cycle stability of high-capacity and high-voltage cathode materials in LMBs, e.g., a cycle stability at 4.5 V in the LiNi0.88Co0.07Mn0.05O2||Li battery with a capacity retention of 81.0% after 500 cycles, and an excellent compatibility in 4.5 V LiCoO2||Li and 4.8 V Li1.13Mn0.517Ni0.256Co0.097O2||Li batteries. The practical applicability of the carefully designed DEE is underscored through successful implementation in pouch cells.

The Influence of Stability in New Power Systems with the Addition of Phase Modulation Functions in Thermal Power Units

The addition of phase modulation function technology to thermal power units is one of the most effective measures to solve dynamic reactive power shortages in the construction process of new power systems. In this paper, the influence of the phase modulation function transformation of thermal power units on the stability of a new power system is studied. Firstly, the new power system stability index is deeply analyzed, and an evaluation system for power system transient stability is constructed from five key dimensions: transient voltage, static voltage, power angle stability, power flow characteristics, and grid support. Secondly, a fuzzy comprehensive evaluation method considering the subjective and objective comprehensive weights is proposed, and the influence of the phase modulation transformation of the thermal power unit on the stability of the receiving-end power grid is quantitatively analyzed. Finally, a CEPRI36 node example model was built based on the PSASP v.7.91.04.9258 (China Electric Power Research Institute, Beijing, China) platform to verify the accuracy and effectiveness of the proposed method. The results show that the proposed method can quantitatively analyze the impact of adding a phase modulation function to thermal power units on the stability of the power system. At the point of renewable energy connection, the static voltage stability index improved by 42.9%, the transient power angle stability index improved by 32.1%, the multi-feed effective short-circuit ratio index improved by 33.9%, and the comprehensive evaluation score improved by 14.7%. These results further indicate that adding a phase modulation function to thermal power units can provide a large amount of dynamic reactive power support and improve the voltage stability and operational flexibility of the system.

Joint Fault Diagnosis of IGBT and Current Sensor in LLC Resonant Converter Module Based on Reduced Order Interval Sliding Mode Observer.

LLC resonant converters have emerged as essential components in DC charging station modules, thanks to their outstanding performance attributes such as high power density, efficiency, and compact size. The stability of these converters is crucial for vehicle endurance and passenger experience, making reliability a top priority. However, malfunctions in the switching transistor or current sensor can hinder the converter's ability to maintain a resonant state and stable output voltage, leading to a notable reduction in system efficiency and output capability. This article proposes a fault diagnosis strategy for LLC resonant converters utilizing a reduced-order interval sliding mode observer. Initially, an augmented generalized system for the LLC resonant converter is developed to convert current sensor faults into generalized state vectors. Next, the application of matrix transformations plays a critical role in decoupling open-circuit faults from the inverter system's state and current sensor faults. To achieve accurate estimation of phase currents and detection of current sensor faults, a reduced-order interval sliding mode observer has been designed. Building upon the estimation results generated by this observer, a diagnostic algorithm featuring adaptive thresholds has been introduced. This innovative algorithm effectively differentiates between current sensor faults and open switch faults, enhancing fault detection accuracy. Furthermore, it is capable of localizing faulty power switches and estimating various types of current sensor faults, thereby providing valuable insights for maintenance and repair. The robustness and effectiveness of the proposed fault diagnosis algorithm have been validated through experimental results and comparisons with existing methods, confirming its practical applicability in real-world inverter systems.

An optimized BPF-based cascaded droop control of indirect matrix converter under unbalanced voltage condition

An optimized BPF-based cascaded droop control of indirect matrix converter under unbalanced voltage condition

Bias‐Independent True Random Number Generator Circuit using Memristor Noise Signals as Entropy Source

Inherent noise characteristics of memristor devices can be utilized in stochastic computing applications such as true random number generators (TRNGs). However, the ratio between capture and emission time can significantly affect the randomness of generated bit streams by TRNGs. Herein, a bias‐independent TRNG circuit is presented, utilizing the random telegraph noise (RTN) signal of the memristor as a random entropy source. This design considers the condition‐dependent RTN characteristics, including capture time and emission time constants, which vary with read voltage (Vread) and temperature conditions in the high‐resistance state of the fabricated memristor. The TRNG circuit, comprising an edge detection circuit and an N‐bit counter, is experimentally demonstrated to validate hardware feasibility with the optimized external clock frequency, which can mitigate the biases induced by Vread and temperature. Finally, the performance of the designed TRNG circuit is evaluated using autocorrelation functions and National Institute of Standards and Technology tests, confirming its capability to produce random number bitstreams.

The Cathode-Electrolyte Interface Constructed with Antioxidant Ascorbic Acid Guides LNMO to Achieve Stable Cycling Under High Voltage Conditions.

LiNi0.5Mn1.5O4 (LNMO) is considered one of the most promising cathode materials for high-energy-density lithium-ion batteries (LIBs). However, free-radical-induced carbonate electrolyte decomposition is a key factor hindering the improvement of battery stability. Inspired by the antioxidative properties of ascorbic acid (AA) in scavenging free radicals, the addition of AA during the electrode fabrication process can effectively terminate free radical chain reactions within the cycling of LNMO. This action prevents severe electrolyte decomposition, thus stabilizing the cathode-electrolyte interface (CEI) and ultimately enhancing battery stability. The results demonstrate that LNMO||Li half-cell with the addition of AA show significantly improved cycling performance after 1000 cycles at 1 C, with a high capacity retention rate of 87.4%, surpassing the 43.6% retention rate achieved by batteries using PVDF alone as a binder. This work introduces an efficient and straightforward strategy for designing functional additives to stabilize phase interfaces, offering an economically efficient choice to enhance the electrochemical performance of the LNMO.

Balancing Activity and Selectivity in Two-Electron Oxygen Reduction through First Coordination Shell Engineering in Cobalt Single Atom Catalysts.

The electrochemical two-electron oxygen reduction reaction (2e- ORR) offers a potentially cost-effective and eco-friendly route for the production of hydrogen peroxide (H2O2). However, the competing 4e- ORR that converts oxygen to water limits the selectivity towards hydrogen peroxide. Accordingly, achieving highly selective H2O2 production under low voltage conditions remains challenging. Herein, guided by first-principles density functional theory (DFT) calculations, we show that modulation the first coordination sphere in Co single atom catalysts (Co-N-C catalysts with Co-NxO4-x sites), specifically the replacement of Co-N bonds with Co-O bonds, can weaken the *OOH adsorption strength to boost the selectivity towards H2O2 (albeit with a slight decrease in ORR activity). Further, by synthesizing a series of N-doped carbon-supported catalysts with Co-NxO4-x active sites, we were able to validate the DFT findings and explore the trade-off between catalytic activity and selectivity for 2e- ORR. A catalyst with trans-Co-N2O2 sites exhibited excellent catalytic activity and H2O2 selectivity, affording a H2O2 production rate of 12.86 and an half-cell energy-efficiency of 0.07 during a 100-hours H2O2 production test in a flow-cell.

Balancing Activity and Selectivity in Two‐electron Oxygen Reduction through First Coordination Shell Engineering in Cobalt Single Atom Catalysts

The electrochemical two‐electron oxygen reduction reaction (2e‐ ORR) offers a potentially cost‐effective and eco‐friendly route for the production of hydrogen peroxide (H2O2). However, the competing 4e‐ ORR that converts oxygen to water limits the selectivity towards hydrogen peroxide. Accordingly, achieving highly selective H2O2 production under low voltage conditions remains challenging. Herein, guided by first‐principles density functional theory (DFT) calculations, we show that modulation the first coordination sphere in Co single atom catalysts (Co‐N‐C catalysts with Co‐NxO4‐x sites), specifically the replacement of Co‐N bonds with Co‐O bonds, can weaken the *OOH adsorption strength to boost the selectivity towards H2O2 (albeit with a slight decrease in ORR activity). Further, by synthesizing a series of N‐doped carbon‐supported catalysts with Co‐NxO4‐x active sites, we were able to validate the DFT findings and explore the trade‐off between catalytic activity and selectivity for 2e‐ ORR. A catalyst with trans‐Co‐N2O2 sites exhibited excellent catalytic activity and H2O2 selectivity, affording a H2O2 production rate of 12.86 [[EQUATION]]and an half‐cell energy‐efficiency of 0.07 [[EQUATION]] during a 100‐h H2O2 production test in a flow‐cell.

Optimizing power sharing accuracy in low voltage DC microgrids considering mismatched line resistances

The main difficulties facing the operation of parallel converters in DC microgrids (DCMGs) are load sharing, circulation current, and bus voltage regulation. A droop controller is commonly used to control current sharing among parallel DC–DC converters due to its simplicity. However, the values of droop parameters impact both bus voltage regulation and the error in current sharing among converters. This study introduces an adaptive and straightforward droop control mechanism designed to estimate droop parameters. The algorithm aims to enhance both bus voltage regulation and load sharing performance within DCMGs. Additionally, to mitigate bus voltage deviation in DCMGs, the second loop shifts the droop lines to maintain voltage regulation at rated values. The proposed method has been compared with the conventional droop controller under variable input voltage and load resistance conditions. Simulation results demonstrate that the presented method outperforms the traditional control approach, achieving superior performance.

Optimizing Switching Activity using LFSR-Driven Logic for VLSI Circuits

In Very-Large-Scale-Integration (VLSI) designs, thorough testing is indispensable for identifying the structural defects of the chip. Timely detection and correcting serious defects are pivotal in preventing faulty chips from reaching customers and avoiding failures. In scan designs, the toggling activity is a critical factor due to the defects between lower cells and metal layers, exacerbated by diverse Process, Voltage, and Temperature (PVT) conditions. These defects significantly impact design testability, quality, and reliability, necessitating meticulous testing to ensure that chips meet the desired specifications. Effectively managing power consumption in the current VLSI landscape is crucial amid the ongoing energy crisis. Balancing the need for Low-Power (LP) with the complexity of integrating transistors onto a single silicon substrate poses significant challenges. As chip densities increase, power dissipation during testing surges, adversely affecting durability, performance, cost, and reliability. Engineers are racing to optimize test power usage, employing advanced Design for Test (DFT) techniques to incorporate efficient power management into Silicon-on-Chip (SoC) designs. Linear Feedback Shift Registers (LFSRs) are phenomenal in addressing DFT parameters like power, and performance, and for better pseudo-random pattern generation. Hence, this paper proposes a groundbreaking approach to power reduction techniques deploying the LFSR architecture, and thus challenging conventional scan-based testing methods. The proposed LFSR architecture is meticulously designed and rigorously tested using Cadence DFT Modus solution on ISCAS’89 benchmarking circuits. Coverage was unequivocally evaluated for Quality of Results (QoR) metrics, such as fault coverage, memory usage, pattern counts, switching activity, fault testing, and runtime. The specific evaluation clearly proved the superiority of the LFSR-based approach over the scan-based architecture. Adopting the novel LFSR architecture resulted in a ~5.6X reduction in toggling activity accompanied by a substantial ~10K pattern reduction and a runtime of nearly ~1.5 hours. Notably, the test power was reduced to 50% showcasing superior efficiency. This approach emerges as the ideal solution for industrial designs providing the best QoR for power, performance, and area. This innovative methodology marks a significant leap toward an energy-efficient and cost-effective VLSI circuit especially for stacked 2.5-3D ICs and chiplets poised to revolutionize chip manufacturing.

The Influence of Iron Particle Contamination on the Breakdown Characteristics of Circulating Mineral Oil under DC Voltage

The presence of metallic particles can lead to the degradation of transformer oil due to the intensification of the electric fields near the conductive components. The primary objective of this research was to investigate the impact of iron impurities on the electrical properties of Mineral Oil (MO), particularly under conditions of continuous flow. Five distinct samples with varying levels of contaminants were carefully prepared for analysis. A specialized chamber was designed to replicate the circulation conditions of oil within an operating transformer. The focus of the investigation was on the breakdown characteristics under DC voltages. The results indicated that higher concentrations of iron impurities were associated with a reduction in breakdown voltage although the circulation of oil exhibited a beneficial effect. To validate these findings, Finite Element Method (FEM)-based simulations were conducted. The analysis of the electric field distribution revealed that iron impurities amplified the electric field intensity, while circulation served to mitigate this effect. Furthermore, the simulations tracking the trajectory of iron particles demonstrated that circulation hindered the particles from reaching the electrodes, thereby diminishing discharge events and lowering the risk of dielectric failure. In conclusion, the circulation of MO enhanced its breakdown voltage, although the presence of iron contamination could still pose a risk under DC voltage conditions.

Theoretical and experimental analysis of unbalanced doubly fed induction generators

In this paper, a novel approach has been developed for the modeling and analysis of doubly fed induction generators operating under unbalanced load conditions. This comprehensive approach considers the derivation of the doubly fed induction generator’s neutral voltage during unbalanced conditions. Using this innovative approach, important and extremely precise signatures on stator currents and voltages have been extracted during a rational simulation time. It has been shown that for unbalanced conditions, an abnormal operation is produced. It is characterized by unbalanced stator voltages, currents, and specific harmonics through the stator variables. These harmonics have been proposed to detect unbalanced conditions. The consistency and reliability of this approach for the analysis and modeling of unbalanced doubly fed induction generators are validated by the coherence and good correlation between experimental and simulation results.

Power quality enhancement of three-phase solar photovoltaic system-based generalized integrator controlled UPQC

Abstract As distributed generation becomes increasingly prevalent, providing reliable and stable electrical energy to the grid is of paramount importance. Therefore, precise monitoring of grid voltage is necessary in order to synchronize compensating current and voltage with the grid. The Dual Second-Order Generalized Integrator (DSOGI) can extract the fundamental positive sequence component from three-phase grid signals, enabling accurate determination of grid phase and current signals for rapid and precise grid compensation. This paper presents a control algorithm for extracting and compensating UPQC reference signals based on the Second-Order Generalized Integrator (SOGI). The improved photovoltaic-fed Unified Power Quality Conditioner System (PV-UPQC) is verified and analyzed under conditions of unbalanced grid voltage, current harmonics, as well as voltage sags and swells. It can be demonstrated that the enhanced system exhibits superior adaptability to the grid.

Research on Structural Parameter Design of High Voltage Plane Switch

Abstract In order to determine the structural parameters of the three electrodes of the high-voltage plane switch, the effects of the main electrode gap distance, trigger electrode width, main electrode radius, electrode thickness and other structural parameters on the static breakdown voltage (SBV) of the high-voltage plane switch were obtained by simulation calculation. The optimized structure parameters of the planar switch are obtained, including primary electrode gap 2.0mm, trigger electrode width 1.2mm, trigger electrode in the center of the two main electrodes, and electrode thickness 4 μ m. The performance of the designed high-voltage planar switch is basically consistent with that of the spark gap switch.