Voltage Changes Research Articles

Study on Thermal Runaway Behavior and Early Warning Algorithm of Ternary Lithium Battery Pack Under Preload Force

Overcharging is a primary cause of thermal runaway in ternary lithium‐ion batteries, often leading to serious safety incidents. Early detection of thermal runaway during overcharging is therefore critical. This study investigates a 5 Ah ternary lithium battery pack, applying appropriate preload force to simulate real‐world conditions. Various overcharge experiments are conducted under different conditions, and changes in battery voltage, temperature, and expansion force are thoroughly analyzed. The results indicate that under the same initial conditions, higher charging rates accelerate the temperature rise in the lithium battery. Additionally, the internal gas generation rate increases, causing a faster rise in edge pressure and leading to earlier battery cracking. Building on these findings, a three‐level early warning algorithm is developed, which comprehensively considers voltage, temperature, and expansion force changes. Experimental validation demonstrates that this algorithm can accurately identify the current stage of thermal runaway and detect the transition to the third warning stage 604 s before complete failure, thus providing critical protection for the safe operation of the battery pack. This study offers valuable guidance for enhancing the monitoring and early warning capabilities of battery management systems.

Study on the Design of Series-Type All-DC Wind Farms Based on Half-Bridge Voltage Balancing Circuits

Offshore wind farms connected in series, with each wind turbine connected in series with one another, enhance the coupling between them. Significant differences in wind speeds between neighboring DC wind turbines (DCWTs) might result in a substantial disparity in the output voltage, hence posing a risk of overvoltage. Nevertheless, implementing voltage-limiting configurations for DCWTs might lead to the dissipation of wind energy, thereby diminishing the wind farm’s capacity to deliver electricity. This work introduces a half-bridge voltage balancing circuit (HVBC) topology as a solution to the issue of DCWT output voltage changes affecting the stable operation of wind farms. The proposed HVBC topology is designed specifically for large-capacity series-connected all-DC wind farms where wind speed variations occur. This design achieves power decoupling for series-connected all-DC wind farms by providing current compensation to the series-connected DCWTs. A control strategy is devised by examining the decoupling principle and operational characteristics of the HVBC. A 60 kV/48 MW tandem-type all-DC wind farm model consisting of six DCWTs in series is built in Matlab/Simulink. The model is then simulated to evaluate its performance under conditions of unequal wind speed, rapid changes in wind speed, and wind turbine failure shutdown. This research verifies the feasibility of the HVBC topology and improves the stability of the series-type all-DC wind farm.

Behavior of corroded HSC beams repaired by sprayed UHTCC and textile: Experimental study and theoretical analysis

Behaviors of twelve high strength concrete (HSC) beams were studied, including one control specimen, five corroded but non-repaired beams, and six corroded beams repaired by sprayed ultra-high toughness cementitious composites (UHTCC) with or without textile reinforcement. Galvanostatic accelerated corrosion technique was adopted, and three targeted corrosion levels (5 %, 10 %, and 15 %) were selected for each tensile steel bar. Corrosion-induced results, such as voltage change, crack initiation, concrete spalling, corrosion crack length and width, and non-uniform corrosion of steel bars were studied and compared with the results observed in normal strength concrete (NSC) beams. Structural behaviors, including failure modes and load-displacement responses were investigated through four-point bending tests. Results revealed that compared to NSC beams, HSC beams sustained more severe damages under a comparable corrosion level. Spalling was observed at a relatively lower corrosion ratio of 4.43 % and the maximum non-uniform corrosion coefficient, which was defined as the ratio of the maximum corrosion ratio to the average corrosion ratio, was 4.28. Corrosion-induced bonding degradation can alter the failure mode of corroded specimens in bending tests from bending to debonding. For repaired beams, however, the bonding degradation effect was reduced and bending failure was observed for all specimens. The bearing capacity of the beams repaired with sprayed UHTCC cannot be restored with a 12.42 % corrosion ratio, while the beams repaired with sprayed UHTCC/textile can recover their capacity even at a 13.6 % corrosion ratio. Furthermore, an improved theoretical model based on the fiber section analysis and virtual work method was developed to predict structural bending responses. The comparison of the experimental and theoretical results indicated the average corrosion ratio-based method may overestimate the loading capacity, especially for the beams with severe corrosion.

A Polyimide Composite-Based Electromagnetic Cantilever Structure for Smart Grid Current Sensing.

Polyimides (PIs) have been extensively used in thin film and micro-electromechanical system (MEMS) processes based on their excellent thermal and mechanical stability and high glass transition temperature. This research explores the development of a novel multilayer and multifunctional polymer composite electro-piezomagnetic device that can function as an energy harvester or sensor for current-carrying wires or magnetic field sensing. The devices consist of four layers of composite materials with a polyimide matrix. The composites have various nanoparticles to alter the functionality of each layer. Nanoparticles of Ag were used to increase the electrical conductivity of polyimide and act as electrodes; lead zirconate titanate was used to make the piezoelectric composite layer; and either neodymium iron boron (NdFeB) or Terfenol-D was used to make the magnetic and magnetostrictive composite layer, which was used as the proof mass. A novel all-polymer multifunctional polyimide composite cantilever was developed to operate at low frequencies. This paper compares the performance of the different magnetic masses, shapes, and concentrations, as well as the development of an all-magnetostrictive device to detect voltage or current changes when coupled to the magnetic field from a current-carrying wire. The PI/PZT cantilever with the PI/NdFeB proof mass demonstrated higher voltage output compared to the PI/Terfenol-D proof mass device. However, the magnetostrictive composite film could be operated without a piezoelectric film based on the Villari effect, which consisted of a single PI-Terfenol-D film. The paper illustrates the potential to develop an all-polymer composite MEMS device capable of acting as a magnetic field or current sensor.

The sodium-bicarbonate cotransporter Slc4a5 mediates feedback at the first synapse of vision

Feedback at the photoreceptor synapse is the first neuronal circuit computation in vision, which influences downstream activity patterns within the visual system. Yet, the identity of the feedback signal and the mechanism of synaptic transmission are still not well understood. Here, we combined perturbations of cell-type-specific genes of mouse horizontal cells with two-photon imaging of the result of light-induced feedback in cones and showed that the electrogenic bicarbonate transporter Slc4a5, but not the electroneutral bicarbonate transporter Slc4a3, both expressed specifically in horizontal cells, is necessary for horizontal cell-to-cone feedback. Pharmacological blockage of bicarbonate transporters and buffering pH also abolished the feedback but blocking sodium-proton exchangers and GABA receptors did not. Our work suggests an unconventional mechanism of feedback at the first visual synapse: changes in horizontal cell voltage modulate bicarbonate transport to the cell, via Slc4a5, which leads to the modulation of feedback to cones.

Predictive Voltage Control in Multi-Modular Matrix Converters under Load Variation and Fault Scenario

This paper presents a model predictive control (MPC) strategy to regulate output voltages in a multi-modular matrix converter topology for isolated loads. The converter system harnesses power from a six-phase permanent magnet synchronous generator (PMSG) to deliver sinusoidal voltages to a three-phase load, with LC filters positioned at the output of each MC module within the multi-modular scheme. The proposed MPC approach ensures that the output voltages remain within acceptable ranges of magnitude, phase, and frequency, even under load variations and system faults. This control strategy is particularly suitable for uninterruptible power supply systems, microgrids or other applications where voltage regulation is critical. Experimental studies validate the effectiveness of the control strategy under various load conditions, reference voltage changes, and simulated system fault scenarios. The results highlight the robustness and reliability of the proposed voltage control using the multi-modular matrix converter.

DUAL LOOP VOLTAGE DROOP REGULATED CONTROLLER FOR DC MICROGRID USING HYBRID PSO AND GGO ALGORITHMS

Abstract DC microgrids are effectively employed in distribution network integration with renewable energy sources. The droop control technique is commonly utilized for DC microgrid regulation during load sharing. It minimizes the potential instability caused by disturbances such as input voltage changes, uncertainty parameters, and constant power load (CPL). Nevertheless, conventional droop control is inadequate in achieving precise current and satisfactory voltage regulation distribution for load sharing. The proposed approach comprises two separate loops for the DC bus voltage regulation and load current distribution, delivering a CVL and CPL to overcome the single optimization voltage controller technique. The primary loop uses the PSO algorithm to precisely manage the current load sharing among two parallel converters. Due to this the instability problems arising from disturbances, and it mitigated by the proposed topology. The multiobjective optimization technique provides notable resilience, rapid dynamic response, and robust stability over considerable variations in load. The secondary loop utilises the GGO algorithm to optimize the parameter to minimize the DC bus voltage regulation, voltage management, reasonable distribution of load power, and suitable reliability. The performance of the voltage regulation enhance & settling time for output voltage has been mitigated more than 31ms times through the proposed controller compared to conventional controller under the variation of CVL, CPL, and input voltage disturbance demonstrated in simulation results.

The comparison study of PI and Sliding Mode control techniques for Buck-Boost converters

This paper compares the performance of a Sliding Mode Control (SMC) and Proportional-Integral (PI) controller under different voltage and load conditions. The study's findings underscore the need to account for load variations in system designs and to continuously seek system optimization irrespective of the controller type chosen. PI controller demonstrates effectiveness under certain circumstances. However, significant drops in voltage and current during abrupt load changes are obtained. On the other hand, SMC enables superior adaptability, efficiently managing voltage transients and load variations without any electrical disturbances, thereby maintaining system stability. A comparative analysis further emphasizes the SMC's superior time response and robustness against reference voltage changes. Consequently, SMC is proven to be a preferable choice over the PI controller in systems experiencing frequent voltage and load variations. However, both controllers achieve the potential for further response time optimization and stability.

Research of the Primary Electric Energy Storage System of a Traction Photovoltaic Module

Purpose. The main idea of the work is that the electric energy generated by photovoltaic installations is supplied in small parts to capacitive energy storage devices of low power, and then these «portions» of energy are supplied to one common, so-called traction storage device. The research is aimed at obtaining time diagrams of current and voltage changes in the proposed system. Methodology. A review of the world literature on the topic of work was conducted. The basis of this research is the analysis of transient processes in the electrical circuits of the system during the transfer of energy from the photovoltaic module to the traction capacitor under the influence of various control signals: series, parallel, combined. The main research method is computer simulation. The Scilab software environment was used to simulate the operation of the electric energy storage system. Findings. The relevance of the research and development of a primary electric energy storage system using a traction photovoltaic module has been proved. The key mathematical dependencies between the parameters of the constituent elements of electrical circuits are established. The structure of a site with electric energy storage with traction photovoltaic modules and a converter-pulse signal unit is proposed. The graphical characteristics of transient processes that occurred during the transfer of energy from low-power capacitive elements to a high-power capacitive element (traction capacitor) were obtained. Originality. For the first time, graphical dependences of energy transfer between system elements were obtained, which allows for a reasonable choice of the parameters of these elements. Also, for the first time, time dependencies describing the law of control of the process of energy transfer between system links were obtained, which will allow determining the rational modes of its operation. Practical value. The results of the research open up new opportunities in the research field in the development of large-scale experimental models of the maglev path structure in the case of the introduction of a system of distributed primary energy storage in a traction photovoltaic module.

A wide-output buck DC-DC power management IC

-This article designs and develops a wide-input voltage, high-efficiency, small-size, and peak current-mode control step-down DC-DC converter. The Cadence Spectre simulation tool is used for system simulation to verify the performance of the chip. The overall research content of the article includes the function of the output under heavy load, light load and the stability of the output under transient load changes. The specific content of the research is buck synchronous step-down DC-DC converter chip with pulse modulated. It is provided with an input-voltage range of 6 V–80 V and maximum output-voltage range 72 V. The chip possesses wide operating temperature range of −20 °C to 130 °C. The 92 % high-efficiency can be achieved by using a PWM/PFM hybrid modulation method. When achieving transient load jump, the output voltage change shall not exceed 150 mV. The maximum load current of the chip is 1 A. Furthermore, the chip is packaged and samples can be obtained, and the output light load/heavy load, and other functions are tested through the circuit board. In addition, the chip achieved tape out by using 0.18 μm CMOS process with size of 2027 μm × 2020 μm. The converter features current mode control to simplify external compensation and optimize transient response through a wide range of inductors and output capacitors. It can be adopted user-programmable soft-start time to prevent inrush current during startup. It also includes thermal shutdown protection to provide safe and smooth operation in operating conditions.

Effects of NiO doping and trench wall tilt on Ga2O3 PiN diodes performance

Gallium Oxide (Ga2O3) is a promising material for next-generation power semiconductors due to its wide bandgap (∼4.9 eV), high Baliga's figure of merit (FOM) (3444 W/cmK), and high breakdown field (Ec, 8 MV/cm). To achieve high blocking and low leakage current, research has been conducted on PN heterojunctions and bevel structures. In this paper, we performed simulations using Sentaurus TCAD to investigate the impact of NiO doping concentration and NiO's trench tilt angle on the electrical characteristics of NiO/Ga2O3 PiN diodes with trench NiO. As the NiO doping concentration increased, the resistance decreased from 21.5 to 7.5 mΩcm2, and we observed the expansion of depletion from NiO to the NiO/Ga2O3 interface. Furthermore, we confirmed a reduction in resistance and a change in breakdown voltage with an increase in NiO trench tilt. By understanding the optimal angle to mitigate the concentration of high electric fields in the edge region, we anticipate the fabrication of stable Ga2O3 PiN diodes.

Sensitivity Analysis and Distribution Factor Calculation under Power Network Branch Power Flow Exceedance

As the scale of power systems continue to expand and their structure becomes increasingly complex, it is likely that branch power flow exceedance may occur during the operation of power systems, posing threats to the safe and stable operation of entire systems. This paper addresses the issue of branch flow exceedance in power networks. To enhance the operational efficiency and optimize the adjustment effects, this paper proposes a method for eliminating branch power flow exceedance by improving the particle swarm optimization (PSO) algorithm through the introduction of sensitivity and distribution factors. Firstly, it introduces the basic theory and calculation methods of sensitivity analysis, focusing on deriving the calculation principles of power flow sensitivity and voltage sensitivity, used to predict the responses of power flow at each branch in the power network to power or voltage changes. Subsequently, the paper provides a detailed derivation of the calculation principles for the line outage distribution factor (LODF), which effectively assesses the changes in branch power flow in the power network under specific conditions. Finally, a method for eliminating branch power flow exceedance based on a combination of sensitivity analysis and PSO algorithm is proposed. Through case analysis, it is demonstrated how to use the sensitivity and distribution factor to predict and control the power flow exceedance issues in power systems, verifying the efficiency and practicality of the proposed method for eliminating branch power flow exceedance. The study shows that this method can rapidly and accurately predict and address branch power flow exceedance in power system, thereby enhancing the operational safety of the power system.

Effect of microwaves on the repair of lead-acid batteries

Abstract Lead-acid batteries are widely used in the automotive industry, and a large amount of waste lead-acid batteries cause enormous pressure on resources and the environment. Repairing aging lead-acid batteries is an effective way to solve this problem. Due to the fact that microwaves can affect most chemical reactions and promote their progress, this paper will study the repair effect of microwaves on lead-acid batteries by combining theory and experiment methods. By analyzing the reaction principle of lead-acid batteries, a multi-physics model is established to study the influence of microwaves on the lead-acid batteries, and an experimental system is built to test the changes in capacity and final charge voltage of lead-acid batteries under the radiation of microwaves. The results demonstrate that microwave treatment significantly enhances the capacity of aging lead-acid batteries, particularly when the initial capacity is slightly above 50% of the rated capacity. Moreover, heating the battery with hot air alone hardly affects its capacity. This study reveals that microwaves have reparative effects on lead-acid batteries, providing a new method for repairing aging batteries.

Long-term changes in transmembrane voltage after electroporation are governed by the interplay between nonselective leak current and ion channel activation

Electroporation causes a temporal increase in cell membrane permeability and leads to prolonged changes in transmembrane voltage (TMV) in both excitable and non-excitable cells. However, the mechanisms of these TMV changes remain to be fully elucidated. To this end, we monitored TMV over 30 min after exposing two different cell lines to a single 100 µs electroporation pulse using the FLIPR Membrane Potential dye. In CHO-K1 cells, which express very low levels of endogenous ion channels, membrane depolarization following pulse exposure could be explained by nonselective leak current, which persists until the membrane reseals, enabling the cells to recover their resting TMV. In U-87 MG cells, which express many different ion channels, we unexpectedly observed membrane hyperpolarization following the initial depolarization phase, but only at 33 °C and not at 25 °C. We developed a theoretical model, supported by experiments with ion channel inhibitors, which indicated that hyperpolarization could largely be attributed to the activation of calcium-activated potassium channels. Ion channel activation, coupled with changes in TMV and intracellular calcium, participates in various physiological processes, including cell proliferation, differentiation, migration, and apoptosis. Therefore, our study suggests that ion channels could present a potential target for influencing the biological response after electroporation.

ТЕСТУВАННЯ ЕЛЕКТРООБЛАДНАННЯ НА НЕСПРИЙНЯТЛИВІСТЬ ДО ПРОВАЛІВ НАПРУГИ, КОРОТКОЧАСНИХ ПЕРЕРИВАНЬ ТА ЗМІН НАПРУГИ

The article examines the testing of electrical equipment for immunity to voltage dips, short-term interruptions, and voltage changes. Special attention is paid to the influence of the starting point of the dip on the sensitivity of electrical equipment, as well as to the study of the resistance of the electromagnetic relay to voltage dips, phase angle jumps, and the starting and ending points of dips. The reaction mechanism of the electromagnetic relay to a voltage drop, its sensitivity to a change in frequency, the presence of harmonic distortions and changes in the nominal value of the voltage are analyzed. The symmetry of a quarter cycle with respect to a point on the wave is considered separately. Ref. 6, fig. 6.

Reflux Power Optimization of a Dual-Active Hybrid Full-Bridge Converter Based on Active Disturbance Rejection Control

The dual-active hybrid full-bridge (H-FDAB) DC–DC converter has great potential in medium-voltage high-power photovoltaic power station applications by introducing a three-level bridge arm to increase the output voltage range. However, its mathematical model and optimum modulation schemes have not been fully explored. Under the traditional PI control, the H-FDAB DC–DC converter will produce significant reflux power, which will lead to a decrease in converter efficiency and output voltage fluctuation. On this basis, this paper proposes a reflux power optimization strategy for an H-FDAB DC-DC converter based on active disturbance rejection control (ADRC). Firstly, the structure and power characteristics of the H-FDAB DC–DC converter are analyzed, and the relationship among the reflux power, the transmission power, and the phase shift angle is derived. Secondly, to reduce the complexity of the control calculation, upon the foundation of dual phase-shifting modulation, the Karush–Kuhn–Tucker (KKT) condition is used to solve for the phase shift angle that corresponds to the minimum reflux power. Simultaneously, we develop an ADRC loop utilizing an extended state observer (ESO) for the real-time estimation of system states. We also consider the sudden changes in input voltage, load switching, and transmission power fluctuations caused by reflux power optimization strategies as system disturbances and compensate for them accordingly. Finally, the experiments conclusively validate the designed control strategy’s correctness and feasibility.

Numerical simulation of reversal point dynamics in intracloud lightning: Back-and-forth promoting effect

Lightning is a self-developing charge transport system that exhibits fundamental manifestations of the macro-scale polarity asymmetry. This asymmetry is tightly connected with peculiarities of the reversal point (the point of zero leader sheath charge or, alternatively, a site where the lightning channel potential coincides with the intracloud one) movement along the leader growth direction. The study presents a stochastic lightning discharge model that is used to analyze the reversal point dynamics. It is shown that the reversal point shifts towards the direction of growth of the dominant leader, i.e. the leader with prevailing peripheral current. The cases of upward and downward directions of the positive leader propagation are considered to study how the difference in altitudes of positive and negative lightning poles influences the mode of reversal point drift. The model predicts that, for the case of an intracloud lightning, the amplitudes of oscillation of reversal point altitude and voltage are of the order of 1 km and 100 MV, respectively, with the reversal point voltage change rate being of the order of 10 MV/ms. The results allow to conclude that the reversal point meandering is a fundamental manifestation of lightning evolution.

Thermally tuned on-chip optical memory

Phase-change materials, known as Chalcogenide alloys, are a promising alternative to traditional random-access memory. They possess characteristics that are particularly beneficial for non-volatile storage applications. The features of the Phase change material Ge-Sb-Te alloy (GST) used for substrate-integrated optical memory include scaling, quick switching times, minimal switching energy, and exceptional thermal stability. The material has two tuneable states, amorphous and crystalline, with the amorphous layer for loading data optically. In contrast, the crystalline state holds the data longer without significant loss. The study designed a classic thermally tuned optical memory on a silicon substrate. It demonstrated a dependency of lattice structure on external voltage and revealed a large storage capacity for information in the form of an optical signal. The heat transport simulation utilized the Heat Transport (HEAT) solver of the Finite Element Eigenmode (FEEM) solver. At the same time, the optical response analysis involved the Finite Difference Time Domain (FDTD) solver of Lumerical. The proposed structure exhibits a memory-switching phenomenon when a temperature shift of about 60 °C from room temperature is induced by a change in the external voltage of 147 mV. These findings have substantial implications for non-volatile storage memory development, providing a potential solution for high-capacity, low-energy data storage.

Capacitor voltage balancing, capacitance monitoring, and fast fault detection in a nested neutral point clamped (NNPC) converter with the reduced number of sensors

In multilevel converters (MCs), system components such as capacitors and semiconductor switches are very susceptible to damage. Furthermore, utilizing voltage sensors to balance capacitor voltages increases the system's cost and complexity while decreasing reliability. This paper presents methods for voltage balancing of capacitors, capacitance monitoring and open-circuit fault detection in nested neutral point-clamped (NNPC) converter with a reduced number of voltage and current sensors. In the proposed method, converter capacitors' voltage and current sensors are eliminated, and only the output sensors are employed to control the converter. In order to balance the voltage of capacitors, their voltages are estimated in three cases without using individual sensors. Comparing the capacitors' measured and estimated voltage change ratios is used to assess their health in the monitoring method. Thus, the capacitors' status can be checked by considering the system's health indicator during each period. Furthermore, the open-circuit fault detection method can identify defective switches within one processing cycle by comparing the converter's measured and standard output voltages in all switching states. The proposed methods have been evaluated in an experimental study of the system, and the results confirmed the effectiveness of the methods based on the new system configuration.© 2017 Elsevier Inc. All rights reserved.

A novel lithium-ion battery state-of-health estimation method for fast-charging scenarios based on an improved multi-feature extraction and bagging temporal attention network

Accurately estimating the state of health (SOH) of fast-charging lithium-ion batteries is crucial for safely and reliably operating battery systems. However, handling data scarcity and rapid charging scenarios under diverse operational conditions is challenging. In this paper, a novel approach for estimating the SOH of lithium-ion batteries (LIBs) is introduced based on an improved multisegment feature extraction and bagging temporal attention network. First, four health features, including the time differences observed at equal voltages, the cumulative integral of voltage changes, the total circuit charge variation and the levels of slope peaks, are identified. Second, a residual bidirectional long short-term memory (Bi-LSTM) attention mechanism is designed to focus on the temporal dimension of battery data by incorporating a multilayered complex neural network design comprising convolutional layers, pooling layers, Bi-LSTM layers and fully connected layers. This design effectively captures the features and relationships contained in battery data. The predictions derived from randomly initialized parameters and multiple submodels are stacked to improve the generalizability of the model. Finally, comprehensive evaluations are conducted through comparative experiments, ablation studies and noise experiments, with six evaluation metrics considered across three datasets. The MAE, RMSE, MAEP and MAXE of the proposed model reach 0.366, 0.605, 0.519 and 1.56, respectively. The results indicate that the proposed method enhances the robustness, resilience and generalizability of the estimates produced under different conditions and noise scenarios.