Voltage Drop Research Articles

Giant Modulation of Magnetoresistance in a Van Der Waals Magnet by In-Plane Current Injection.

Efficient magnetization control is a central issue in magnetism and spintronics. Particularly, there are increasing demands for manipulation of magnetic states in van der Waals (vdW) magnets with unconventional functionalities. However, the electrically induced phase transition between ferromagnetic-to-antiferromagnetic states without external magnetic field is yet to be demonstrated. Here, the current-induced magnetic phase transition in a vdW ferromagnet Fe5GeTe2 is reported. Based on magneto-transport measurements and theoretical analysis, it is demonstrated that transition in the interlayer magnetic coupling occurs through vertical voltage drop between layers induced by current which is attributed to high anisotropy of the resistivity caused by the vdW gaps. Such magnetic phase transition results in giant modulation of the longitudinal magnetoresistance from 5% to 170%. The electrical tunability of the magnetic phase in Fe5GeTe2 with current-in-plane geometry opens a path for electric control of magnetic properties, expanding the ability to use vdW magnets for spintronic applications.

Specificity and tunability of efflux pumps: A new role for the proton gradient?

Efflux pumps that transport antibacterial drugs out of bacterial cells have broad specificity, commonly leading to broad spectrum resistance and limiting treatment strategies for infections. It remains unclear how efflux pumps can maintain this broad spectrum specificity to diverse drug molecules while limiting the efflux of other cytoplasmic content. We have investigated the origins of this broad specificity using theoretical models informed by the experimentally determined structural and kinetic properties of efflux pumps. We developed a set of mathematical models describing operation of efflux pumps as a discrete cyclic stochastic process across a network of states characterizing pump conformations and the presence/absence of bound ligands and protons. These include a minimal three-state model that lends itself to clear analytic calculations as well as a five-state model that relaxes some of the simpler model's most strict assumptions. We found that the pump specificity is determined not solely by the drug affinity to the pump-as is commonly assumed-but it is also directly affected by the periplasmic pH and the transmembrane potential. Therefore, changes to the proton concentration gradient and voltage drop across the membrane can influence how effective the pump is at extruding a particular drug molecule. Furthermore, we found that while both the proton concentration gradient across the membrane and the transmembrane potential contribute to the thermodynamic force driving the pump, their effects on the efflux enter not strictly in a combined proton motive force. Rather, they have two distinguishable effects on the overall throughput. These results highlight the unexpected effects of thermodynamic driving forces out of equilibrium and illustrate how efflux pump structure and function are conducive to the emergence of multidrug resistance.

Enhancing Voltage and Power Stability in Distribution System with Photovoltaic from the Benefits of Battery Energy Storage

This paper presents a method of enhancing voltage and power stability in a distribution system with the photovoltaic benefits of battery energy storage. The objective is to use photovoltaic-distributed generation and a battery energy storage system in order to reduce power loss to a minimum and generate a voltage up to or above 0.95 p.u, which is the voltage standard in Thailand. This paper used MATLAB (Version R2024b-acdemic use) to conduct test experiments, and the system for the case studies is an IEEE 33-bus radial distribution system. There are five study cases in this paper. Case 1 is before the installation of the photovoltaic and battery energy storage system. Case 2 is the installation of the photovoltaic-distributed generator in four buses. Case 3 is the installation of the photovoltaic-distributed generator in only one bus. Case 4 is the installation of the photovoltaic distributed generator in two buses that have the most voltage drop. Case 5 is the installation of the photovoltaic-distributing generator in four buses and the battery energy storage system in two buses. The results show that Case 5 is the best because the voltage drop is never below 0.95 per unit or below the lowest power loss.

Eliminating the Sudden Voltage Drop of Alkaline Polymer Membrane Fuel Cells at the Initial Discharge Stage

Eliminating the Sudden Voltage Drop of Alkaline Polymer Membrane Fuel Cells at the Initial Discharge Stage

Grid Connection of a Squirrel-Cage Induction Generator Excited by a Partial Power Converter

This article concerns the connection process of a squirrel-cage induction generator to the grid/microgrid. Typically, the generator is unexcited, and its connection to the grid is made directly via a switch. This connection causes a high inrush current and grid voltage drop, which local consumers notice. This article proposes a robust power system consisting of the squirrel-cage induction generator, a power electronic converter, and a capacitor bank, all connected in parallel. The proposed configuration and a dedicated control system eliminate the inrush current and compensate for the generator’s reactive power during grid-tied operation. The converter controls the generator voltage build-up to adjust the generator voltage to the grid voltage (controlled excitation) and connects the generator to the grid, minimising distortions. Moreover, the system is robust because the failure of the converter does not stop the power generation, unlike a system with a back-to-back converter, where the converter links the generator and the grid. Furthermore, the parallel-connected converter has a significantly reduced power rating because it is only rated for a part of the reactive generator power. The rest of the reactive generator power is delivered by the fixed capacitor bank. The article presents the system configuration, the control method, and laboratory results confirming the system’s effectiveness in maintaining high-quality grid voltage during generator-to-grid connection and high-quality power supplied to the grid.

A Robust Linear Active Disturbance Rejection Control for Renewable Energy Grid-Connected System Based on APF

With the energy transition and changes in electrical load structures, harmonic distortion in power systems is increasingly threatening grid stability, especially during the integration of renewable energy sources. Active power filters (APFs) are commonly used to improve power quality, but current fluctuations and voltage instability caused by DC-side capacitor charging and discharging hinder effective harmonic compensation. To address this, this paper presents a method combining a variable-step-size adaptive linear predictor with linear active disturbance rejection control (VALP-LADRC). By integrating an adaptive linear predictor (ALP) with LADRC, the proposed method effectively reduces the impact of disturbances on control, improving voltage regulation and harmonic compensation, and enhancing renewable energy grid integration. To address delays during the adjustment of initial parameters in the adaptive predictor, we combine it with a variable-step-size algorithm, significantly improving disturbance rejection and tracking accuracy, while solving voltage drop issues. The simulation results in a photovoltaic grid-connected system show that VALP-LADRC effectively mitigates disturbances, ensures voltage stability, and enhances power quality. This approach offers a promising solution for supporting sustainable development through better renewable energy integration and improved power quality.

Trench MOS Schottky Diodes: A Physics-Based Analytical Model Approach to Charge Sharing.

Trench MOS Barrier Schottky (TMBS) rectifiers offer superior static and dynamic electrical characteristics when compared with planar Schottky rectifiers for a given active die size. The unique structure of TMBS devices allows for efficient manipulation of the electric field, enabling higher doping concentrations in the drift region and thus achieving a lower forward voltage drop (VF) and reduced leakage current (IR) while maintaining high breakdown voltage (BV). While the use of trenches to push electric fields away from the mesa surface is a widely employed concept for vertical power devices, a significant gap exists in the analytical modeling of this effect, with most prior studies relying heavily on computationally intensive numerical simulations. This paper introduces a new physics-based analytical model to elucidate the behavior of electric field and potential in the mesa region of a TMBS rectifier in reverse bias. Our model leverages the concept of shared charge between the Schottky and MOS junctions, capturing how electric field distribution is altered in response to trench geometry and bias conditions. This shared charge approach not only simplifies the analysis of electric field distribution but also reveals key design parameters, such as trench depth, oxide thickness, and doping concentration, that influence device performance. This model employs the concept of shared charge between the vertical Schottky and MOS junction. Additionally, it provides a detailed view of the electric field suppression mechanism in the TMBS device, highlighting the significant effects of the inversion charge on the MOS interface. By comparing our analytical results with TCAD simulations, we demonstrate strong agreement, underscoring the model's accuracy and its potential to serve as a more accessible alternative to resource-intensive simulations. This work contributes to a valuable tool for TMBS device design, offering insights into electric field management that support high-efficiency, high-voltage applications, including power supplies, automotive electronics, and renewable energy systems.

ENHANCING VOLTAGE STABILITY AND ENERGY OUTPUT OF PLTM SALIDO IN THE PLN DISTRIBUTION NETWORK

Distributed generation (DG) integration in PLN’s extended distribution network often encounters voltage instability issues due to high voltage drops. These challenges restrict power delivery and can lead to disconnection, particularly during peak load conditions. This study investigates methods to enhance voltage stability and optimize the energy output of PLTM Salido. Using ETAP Power Station software, various operational schemes were simulated to address the problem of low terminal voltage. The study focused on the impact of reactive power injection and governor settings optimization to maintain generator performance under high demand. Results indicate that reactive power injection significantly improves terminal voltage, ensuring continuous power delivery. Adding a third generator unit further increased energy supply capacity, leveraging the full potential of available hydropower. The optimized operation of PLTM Salido with two generators increased daily energy output by 32.2%, while introducing a third generator boosted energy delivery by 107%. This research highlights the critical role of reactive power management and system configuration in enhancing the performance of small-scale hydropower plants in rural distribution networks.

Algorithm optimization based on intelligent management of computer electrical equipment: A comprehensive method for PT power monitoring and remote fault indicator

In response to the accuracy limitations and response delays in current power and fault detection of electromechanical equipment, long short-term memory (LSTM) network algorithm was applied for intelligent optimization and management. Firstly, voltage and power data were collected through a potential transformer (PT), and wavelet transform (WT) was applied to remove noise. Fast Fourier transform (FFT) was utilized to extract key features. Secondly, a multi-layer long short-term memory network was designed, and back propagation algorithms and time series power data were used for LSTM network training to analyze abnormal fluctuations and trends in power data in real-time, and adjust threshold settings. Then, combining the model output and historical fault data, a fault mode knowledge base was established. Potential faults were determined through pattern matching, and signals were sent out through remote indicators. Finally, the algorithm model was evaluated. The research results showed that the weighted response time of voltage drop faults was shortened by 3.3%, and the information entropy values of nine experiments were distributed from 5.11 to 5.28. The diagnostic accuracy for frequency drift was improved by 11.1%. The comprehensive algorithm model used can effectively improve the accuracy of power monitoring and response speed. This study optimizes power monitoring and fault diagnosis by applying the LSTM network algorithm, addressing the limitations of existing methods in terms of real-time performance and accuracy. It effectively enhances the fault prediction capability and response speed of power systems, offering significant application value in the fields of smart grids and equipment management.

High‐efficiency multilevel inverter topology with minimal switching devices for enhanced power quality and reduced losses

AbstractThe advent of multilevel inverters (MLIs) has brought significant advancements in their applications across industrial, residential, and renewable energy sectors, as they produce high‐quality output voltage that closely approximates a sinusoid in small voltage steps or levels, resulting in lower total harmonic distortion (THD) and reduced electromagnetic interference (EMI). However, the MLI topologies require more switching unidirectional/bidirectional semiconductor devices with high standing voltage, gate drivers, and complex control strategies while attaining higher voltage levels. From this perspective of reducing component count and gate drivers, the objective is to develop a new MLI topology that overcomes the drawbacks above. In this article, a novel MLI topology is introduced in symmetric and asymmetric configurations aiming to attain fewer power electronic devices for synthesizing more steps in the load voltage in contrast with conventional topologies. The idea behind the approach is coining the series connected voltage source, which imbibes bidirectional current flow with an additional voltage source for performing algebraic operation under asymmetrical modes of operation. The proposed topology uses minimal on‐state switching devices leading to a diminution of power loss and voltage drop. The suggested topology is optimized for a fewer number of power devices, an input DC supply, and auxiliary gate drivers to achieve a maximum voltage level in the load terminals. The suggested topology has been verified in SIMULINK and the laboratory prototype is constructed in line with the simulated response to demonstrate its performance suitable for real‐time applications.

Distribution network clustering for reactive power planning and distributed voltage control

AbstractAccording to the inherent characteristics of power systems, the voltage reduction is different in each part of power system. The voltage drop is directly proportional to the demand current and the total impedance between the source and the loads. Therefore, in distribution system voltage/VAr control is more important rather than transmission network, because of higher line R/X ratios rather than the transmission network and customers or end‐users receive power through a higher impedance and experience a larger voltage drop in distribution system. This work presents multistage optimal reactive power planning and clustering the distribution network to implement distributed voltage/VAr control approach. At first, reactive power planning to reduce active power losses and save costs has been investigated. According to the result of the first stage, the power system is clustered into some partitions using spectral clustering and reactive power weighted matrix. The optimal number of clusters has been evaluated and determined by four criteria and the clusters are defined by fuzzy c‐mean method which gives better vision about cluster boundaries. Finally, a sensitivity‐based approach has been used to determine the precise location of VAr resources and the results show that voltage/VAr control in a clustered distribution system has more acceptable outcomes rather than centralized voltage/VAr control in the whole distribution network.

High-Voltage studies in the new GE1/1 GEM station at CMS experiment

Part of the muon upgrade of the CMS Experiment for the High-Luminosity Large Hadron Collider consists of three new GEM stations, GE1/1, GE2/1 and ME0. The purpose of these stations is to increase the redundancy of the CMS muon spectrometer in the forward endcap regions and to extend the acceptance of the detector up to a pseudorapidity |η| ∼ 2.8 with the ME0 station. To achieve this result, these detectors must be able to withstand the background radiation of the installation environment, with a rate capability of up to 150 kHz/cm2.The first station, GE1/1, was installed during the Long Shutdown 2. Since the start of Run 3 in 2022, GE1/1 has been active in CMS operations and data acquisition; this will be the focus of this work. The presence of high radiation in the area where the detector operates is a challenge for the High-Voltage system, since a large charge has to be handled without reducing the effective gain of the detector. This phenomenon leads to a drop in the effective voltage applied and therefore voltage compensation must be applied to have a stable gain. We quantify this effect by measuring the currents flowing in the High-Voltage system of GE1/1 detectors and comparing them with the observed particle hit-rate measured in the same chambers, as a function of LHC beam luminosity. This study, based on data provided by detectors already installed in CMS, aims to test the performance of detectors in terms of rate capability in order to help the development of the GE1/1 station and to support the development and to highlight the operational needs of the next two stations to be built, GE2/1 and ME0.

Development of a new SVR for improving PVHC upon voltage drop phenomenon

Development of a new SVR for improving PVHC upon voltage drop phenomenon

Voltage drop design method of aircraft main feeders based on a twisted laying

Voltage drop design method of aircraft main feeders based on a twisted laying

Volt-VAr Management System

In this paper, the newly developed system has been integrated with auxiliary systems such as GIS (Geographic Information System), SCADA-DMS, and Field Device Controllers. It monitors the active and reactive power flow of feeders at TEİAŞ (Turkey's Electricity Transmission Corporation) transformer stations, while enabling the remote monitoring and automatic switching of reactors, capacitors, and MCR (Magnetic Controlled Reactors). Optimized reactive power and voltage management with the VVMS (Volt-VAr Management System) improves the power factor, reduces technical losses, and lowers energy costs. It also prevents low or high voltage issues through voltage regulation, thereby improving power quality. Additionally, reactive power management performs necessary calculations to ensure that inductive and capacitive limits are not exceeded, and the relevant equipment can be controlled remotely or via protection relays. The system aims to reduce energy losses and voltage drops, providing more efficient grid management.

Development of Battery-Independent Illumination Drones Integrated into Tethered UAVs for Extended Operations

This study presents the design of an unmanned aerial vehicle (UAV) specifically developed for extended illumination in surveillance, search and rescue (SAR) operations, security enforcement, border surveillance, and other applications requiring lighting, particularly in disaster areas. Traditional battery-powered UAVs have limited operational time; therefore, a tethered drone design was implemented in this study to overcome flight duration constraints. The direct current (DC) energy required for the tethered drone is supplied by a Gold Series switch-mode power supply (SMPS) mounted on the drone. The alternating current (AC) energy needed for the SMPS is transmitted through a cable. Additionally, the light-emitting diode (LED) projector, operating on AC 220 volts, is powered by the same cable that supplies the drone, eliminating the need for an additional DC converter. This design choice reduces weight and ensures an optimized configuration. The projector is mounted on servos with dual-axis capability, allowing both horizontal and vertical movement to precisely illuminate the target area. Although studies on tethered and illumination drones exist in the literature, this work combines two distinct drone systems to create a more efficient UAV design. In the design process, considerations were made for various environmental conditions, particularly wind. Consequently, the thrust-to-weight (T/W) ratio was determined to be 1.54. For cable cross section, a 1.5% voltage drop was accounted for, yielding a required cross section of 1.16mm². However, to ensure safety and reliability, a cable with a cross section of 1.5mm² was selected. This proposed model, distinct from other studies in the literature, offers a practical design for field applications, particularly for night SAR operations in disaster zones such as earthquake sites, due to its point-focus illumination capability and extended flight duration.

Achieving ultralow leakage current in Schottky-MIS cascode anode lateral field-effect diode based on AlGaN/GaN HEMT

In this paper, we design and fabricate a Schottky-metal-insulator-semiconductor (MIS) cascode anode GaN lateral field-effect diode (CA-LFED) to achieve ultralow reverse leakage current (ILEAK). The device based on AlGaN/GaN high-electron-mobility-transistor (HEMT) includes a normally-off MIS-controlled channel that is cascoded with a high barrier height Schottky contact. At reverse bias, the high electric-field is effectively prevented by the normally-off MIS-controlled channel edge. Together with the high barrier height Schottky contact, this feature significantly suppresses the ILEAK. Supported by the device fabrication, the CA-LFED with high breakdown voltage (BV) > 600 V shows an ultralow ILEAK of 3.6 × 10−9 A/mm as well as a low forward voltage drop (VF) of 2.2 V. The performance suggests that the CA-LFED can be a promising candidate for ultralow ILEAK and better VF-ILEAK trade-off GaN power diode applications.

One Micrometer Channel Length, Coplanar Polycrystalline InGaO Thin Film Transistors Exhibiting 85 cm2 V−1 s−1 Mobility and Excellent Bias Stabilities by Using Offset Engineering

AbstractThe effect of N+ resistivity in the offset region, for ≈1 µm channel length coplanar, polycrystalline InGaO (PC‐IGO) thin‐film transistors (TFTs) is studied. The room temperature deposited amorphous IGO is solid phase crystallized at 450 °C. The PC‐IGO TFT exhibits a maximum effective field‐effect mobility (µFE) of ≈86.69 cm2 V−1 s−1, a threshold voltage of ≈1.5 V, and a subthreshold swing of ≈300 mV decade−1, with remarkable stability under bias and temperature stress. The offset length (Loff) is varied from 1 to 3 µm and their electrical performances are analyzed. Upon increasing the Loff from 1 to 3 µm, the on current (Ion) and the µFE drops from 50.31 to 17.72 µA and 85.40 to 67.64 cm2 V−1 s−1, respectively, which can be attributed to a greater voltage drop in the Loff, resulting in the reduction of effective VDS applied to the channel. Technology computer‐aided design simulations shows that at the sheet resistance of 14.5 Ω sq−1. in the N+ offset region, the Ion dependency disappears with the change in Loff, which is attributed to the negligible voltage drop. These results provide valuable insight into optimizing N+ doping, for high‐performance, short‐channel coplanar oxide TFTs.

Abnormal widening of the domain touching the electrode during in-plane local switching in lithium niobate

The qualitatively different domain evolution scenarios for different polarities of applied voltage pulses have been studied. For positive pulse, the domain demonstrates only slight width increase during further switching and high stability during subsequent domain imaging. For negative pulse, faster domain widening at the electrode as compared to the domain base leads to change in the type of charged domain wall (CDW) from tail-to-tail (t2t) to head-to-head (h2h) as well as formation of the domain teeth at CDW and an array of wedge-like domains. Additional domain imaging leads to reconstruction of the wedge-like domain with t2t CDW. It was demonstrated by numerical simulation that the switching field is above the threshold for step generation in wide region along the electrode. This field stimulates the formation of above-mentioned domain structure. The absence of this effect for positive pulse has been attributed to the huge difference in conductivity of t2t and h2h CDWs. The current along conductive h2h CDW after domain touching results in decrease in the tip bias due to voltage drop on the series resistance. The stability of the domains growing from the tip was attributed to effective screening of depolarization field by the injected charge. The ineffective screening at the electrode due to absence of charge injection stimulates domain backswitching. The obtained knowledge is useful for further development of domain engineering methods in thin films for the fabrication of periodically poled waveguides.

An advanced 1D physics-based model for PEM hydrogen fuel cells with enhanced overvoltage prediction

A one-dimensional, dynamic, two-phase, isothermal model of proton exchange membrane fuel cell systems using a finite-difference approach has been developed. This model balances the simplicity of lumped-parameter models with the detailed accuracy of computational fluid dynamics models, offering precise internal state descriptions with low computational demand. The model’s static behavior is validated experimentally using polarization curves. In addition, a novel physical parameter, the limit liquid water saturation coefficient (slim), is introduced in the overvoltage calculation, replacing the traditional limit current density coefficient (ilim). This new parameter links the voltage drop at high current densities to the amount of liquid water present in the catalyst layers and the operating conditions of the fuel cell. Additionally, it has been observed that slim is influenced at least by the gas pressure applied by the operator. This newly established link is promising for optimizing the control and thereby improving the performance of fuel cells.