High Voltage Research Articles

The synergistic effect of vertical structural parameters of vertical-type two-dimensional hole gas diamond MOSFETs on improving the overall performance of devices based on TCAD simulation

Vertical-type two-dimensional hole gas (2DHG) diamond metal-oxide-semiconductor field effect transistors (MOSFETs), featuring vertical geometry and typically p-channel, are poised for application in future logic technology, high-voltage and high-power miniaturization complementary circuits. P-channel achieving high breakdown voltage and low on-resistance can be realized through the use of p− drift layer, while a trench structure is shown to be beneficial for increasing the drain current density of vertical-type devices. However, the cumulative impact of these key parameters on the performance of vertical-type diamond MOSFETs remains unclear. In this paper, we explore the physical mechanism that how the key parameters design affects on off-state, breakdown and output characteristics has been simulated using Silvaco TCAD tools. We propose a vertical-type trench-gate 2DHG diamond MOSFET that is favorable for general integration applications and exhibits equivalent performance to the double-gate vertical structure without relying on a high concentration of nitrogen doped layer. This demonstrates that our work offers a universal approach for optimizing the comprehensive device performance in vertical-type structures, accounting for the effects of multiple parameters across all wide bandgap material-based FETs.

A new topology of non-isolated AC-DC quadratic boost converter with enhanced power traits

A novel AC-DC quadratic boost converter (QBC) topology is presented in this paper which can provide higher power factor (PF), lower total harmonic distortion (THD) and higher voltage when compared to a conventional AC-DC boost convertero This is achieved by using additional switched capacitor and switched inductor in the power processing stage. The presented converter is analyzed theoretically, and a voltage gain equation is derived. A simulation model is created to evaluate the converter performance under various duty cycles, switching frequency, and changing output load. The input PF, THD, and voltage gain of the simulated model were compared with conventional converter to determine the validity of the suggested converter circuit. The results show that the efficiency, PF, THD and voltage gain value reaches approximately 97.9%, 0.98, 16.14, and 2.83 respectively at a duty cycle of 50% with fixed output load of 100 Ω. A dual loop voltage and current controller is also arrayed with the proposed circuit which allows further enhancement in PF (0.997) and THD (7.45%). This converter can be a suitable option for systems where isolation is not necessary but high PF, high voltage gain and low THD are required.

Lithium insertion/extraction mechanism in Mg2Sn anode for lithium-ion batteries

Due to its high capacity and excellent voltage properties, the Mg2Sn intermetallic phase is considered a promising anode material for next-generation lithium-ion batteries. However, the rapid capacity loss with cycling presently limits the application of Mg2Sn-based anodes. In this work, the Mg2Sn intermetallic phase was synthesized via a conventional casting method, and mechanisms of lithium ions intercalation into Mg2Sn alloy anodes were systematically studied. Density functional theory (DFT) calculations and electrochemical analyses identified two pathways involving four electrochemical reactions for Li+ intercalation/extraction in the Mg2Sn phase. The first pathway involves the insertion reaction of lithium ions into the octahedral sites of the Mg2Sn face center cubic (FCC) matrix, whilst the second involves the substitution of Mg by Li ions (releasing Mg metal). Furthermore, ex-situ EIS analysis and DFT calculations verified that adjusting the cut-off voltage range could control the reaction pathways. Excessively high or low cut-off voltages adversely impact the stability of the Mg2Sn anode. At cut-off voltages between 0.1 and 1 V, Mg2Sn anodes show very good capacity retention (78 % after 50 cycles), benefiting from the minimized formation of metallic Mg and Sn phases.

SHE PWM based 21 level inverters with hardware analysis

Recently, the advancement of multilevel inverters (MLI) has been a crucial factor in high power and medium voltage applications. This MLI has multiple topologies and has been used in a variety of applications. Cascaded MLI is preferred over other forms of multilevel inverter topologies. Nonetheless, significant obstacles are encountered when implementing these topologies. They necessitate an increased number of switches, DC sources, capacitors, and diodes. Increased losses and total harmonic distortion (THD) will be present in the system. In addition, the MLI is more expensive. The better construction of a multilevel inverter results in more output levels with fewer switches, sources, and driver circuits, as well as low THD. A new single-phase cascaded asymmetrical DC voltage sources based multilevel inverter design and the selective harmonic elimination (SHE) approach are used to attain these goals. After confirming in MATLAB/Simulink, the hardware implementation of the multilevel inverter in 21 levels was completed in this article.

Simulation and optimization of EMI filter of conducted emission for high voltage gain DC-DC converter

In the continuity of the work on design of high voltage gain DC-DC converter, used for feeding the CubeSat electrospray thrusters with a variable output voltage according to the maneuver size, this paper introduces a simulation of the converter model with MATLAB/Simulink to determine its conducted emission level. By referring to the MIL-STD-461 standard, a required passive electromagnetic interference (EMI) filter parameters are calculated to reduce, under thresholds, the converter noise. With consideration of the available volume and power constraints in this kind of satellite, the design of common-mode (CM) choke is optimized with proposed procedure optimization, so as to reduce its volume and electrical losses. Also, this optimization procedure can be generalized and applied for any passive EMI filter design.

Investigating the effects of corrosion parameters on the surface resistivity of transformer’s insulating paper using a two-level factorial design

The integrity of the insulation in oil-filled power transformers, shunt reactors, and high voltage bushings can be affected when copper dissolves in the insulating oil and then deposits onto the paper insulation. The presence of dissolved copper in the oil increases dielectric losses, while copper deposition significantly improves the conductivity of the paper insulation. Various factors, including temperature, oxygen, sulfur groups, passivators, and ageing time, have been found to contribute to the acceleration of corrosion activity in transformer insulating oils. Unfortunately, there is a lack of extensive research focused on systematically analysing and measuring the impact of corrosion-related factors on the dissolution of copper in transformer insulating oils and the deposition of copper onto solid insulation surfaces (Kraft paper). Therefore, this study aims to thoroughly examine the effects of corrosion factors on copper and sulfur deposition on Kraft paper insulation when it is submerged in transformer mineral oil (TMO). Using a two-level (2k) factorial design, we investigated three crucial factors: i) oil temperature, ii) elemental sulfur concentration, and iii) ageing time. It is worth mentioning that the results obtained from the two-level factorial design indicate that the surface resistivity is primarily affected by the temperature of the oil. This factor alone explains a significant 38.68% of the observed variation. In order to improve predictability, a regression model was created to estimate the surface resistivity of TMO-impregnated paper insulation. This model takes into account factors such as oil temperature, elemental sulfur concentration, and ageing time.

New control scheme for a dynamic voltage restorer based on selective harmonic injection technique with repetitive controller

Repetitive controller and selective harmonic injection technique (SHI) in medium and low voltage distribution networks improve dynamic voltage restorer (DVR) DC bus voltages as well as nullify power quality (PQ) problems. DVRs use sinusoidal pulse width modulation (SPWM) firing control, but DC bus use seems to be limited, affecting density, cost, and power packaging. By adding 1/6th of the 3rd harmonic waveform to the basic waveform, SPWM yields the developed model. According to the findings, 15% of DC bus usage improves and produces high voltage AC. Nevertheless, just control systems perturb PQ. The proposed controller uses feed forward and feedback to enhance transient response and justify stable zero error. 3rd third harmonic injection pulse width modulation (THIPWM) improves total harmonic distortion (THD) in the proposed scheme. Power system computer aided design (PSCAD) simulation produced high accuracy for THIPWM and repetitive controllers.

Design and Implementation of an Interleaved High Efficiency and High Voltage Gain Converter With Minimum Switch Count for Renewable Energy Integration

Design and Implementation of an Interleaved High Efficiency and High Voltage Gain Converter With Minimum Switch Count for Renewable Energy Integration

Impact of grading capacitor on transient recovery voltage due to shunt reactor de-energization for different values of current chopping

This paper investigates the impact of grading capacitors on transient recovery voltage (TRV) during shunt reactor switching in high voltage systems, considering different levels of current chopping. Shunt reactor de-energization can result in voltage surges and instability due to current chopping effects. The study utilizes simulation models using ATP-Draw software to assess the effectiveness of grading capacitors in mitigating TRV under various operating conditions as well as of using a proposed method to mitigate the excessive TRV across the circuit breaker. The findings provide valuable insights into managing TRV during shunt reactor switching, enhancing power system stability and reliability. The results obtained showed that the TRV across the circuit breaker decreased by 61.5% by using circuit modification as well as adding a grading capacitor.

Prototype Model of Electric Locomotive Traction System

Abstract: Electrical locomotive is driven by DC series motor of 12V. The torque produced by motors is used to move the locomotive. The main supply to the motor is given through pantographs. The total length of path is 6 feet approximately. The other main equipment are rectifiers, Step-down transformer. Rectifier is used for conversion of alternating current to direct current, Step-down transformers used for convert high voltage power to a low voltage The railway is one of the largest and oldest methods of the transportation in our country serving many people in many ways. The major problem in railways is derailing and obstruction to the locomotive in different ways. Traction is basically two types, electrical traction and nonelectric traction. Electric traction is most advantageous and economical with less maintenance when compared to other.

Localized High-Concentration Sulfone Electrolytes with High-Voltage Stability and Flame Retardancy for Ni-Rich Lithium Metal Batteries.

The localized high-concentration electrolyte (LHCE) propels the advanced high-voltage battery system. Sulfone-based LHCE is a transformative direction compatible with high energy density and high safety. In this work, the application of lithium bis(trifluoromethanesulphonyl)imide and lithium bis(fluorosulfonyl)imide (LiFSI) in the LHCE system constructed from sulfolane and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) is investigated. The addition of diluent causes an increase of contact ion pairs and ionic aggregates in the solvation cluster and an acceptable quantity of free solvent molecules. A small amount of LiFSI as an additive can synergistically decompose with TTE on the cathode and participate in the construction of both electrode interfaces. The designed electrolyte helps the Ni-rich system to cycle firmly at a high voltage of 4.5V. Even with high mass load and lean electrolyte, it can keep a reversible specific capacity of 91.5% after 50 cycles. The constructed sulfone-based electrolyte system exhibits excellent thermal stability far beyond the commercial electrolytes. Further exploration of in-situ gelation has led to a quick conversion of the designed liquid electrolyte to the gel state, accompanied by preserved stability, which provides a direction for the synergistic development of LHCE with gel electrolytes.

Dual-Site Doping in Transition Metal Oxide Cathode Enables High-Voltage Stability of Na-Ion Batteries.

Designing cathode materials that effectively enhancing structural stability under high voltage is paramount for rationally enhancing energy density and safety of Na-ion batteries. This study introduces a novel P2-Na0.73K0.03Ni0.23Li0.1Mn0.67O2 (KLi-NaNMO) cathode through dual-site synergistic doping of K and Li in Na and transition metal (TM) layers. Combining theoretical and experimental studies, this study discovers that Li doping significantly strengthens the orbital overlap of Ni (3d) and O (2p) near the Fermi level, thereby regulates the phase transition and charge compensation processes with synchronized Ni and O redox. The introduction of K further adjusts the ratio of Nae and Naf sites at Na layer with enhanced structural stability and extended lattice space distance, enabling the suppression of TM dissolution, achieving a single-phase transition reaction even at a high voltage of 4.4V, and improving reaction kinetics. Consequently, KLi-NaNMO exhibits a high capacity (105 and 120 mAh g-1 in the voltage of 2-4.2V and 2-4.4V at 0.1 C, respectively) and outstanding cycling performance over 300 cycles under 4.2 and 4.4V. This work provides a dual-site doping strategy to employ synchronized TM and O redox with improved capacity and high structural stability via electronic and crystal structure modulation.

Analysis of heating defects in extension rods of extra-high voltage direct current overhead transmission lines

This paper studies the overheating defect of an extension rod in a ± 800 kV extra-high voltage direct current overhead transmission line, and proposes various factors that affect the overheating of the extension rod. Establish an equivalent model of an extra high voltage DC transmission line based on equipotential point and line parameter analysis, and calculate the model parameters. The proposed model can also be applied to ultra-high voltage DC overhead transmission lines such as ± 500 kV, and has strong universality. Simulation experiments show that if the equivalent resistance value of the split wire side is reduced by 0.01Ω, the power loss on the extension tie rod can be increased to 380.951 W; if the equivalent resistance value of the jumper side is increased by 0.01Ω, the power loss on the extension tie rod can be increased to 273.41 W. Combined with theoretical analysis and simulation verification, it is concluded that the main factor affecting the overheating of the extension rod is the change in the resistance value on the jumper side caused by the increase in contact resistance. A systematic troubleshooting plan for related defect problems is proposed, which has important reference and guidance significance for such line fault problems.

Research on Influencing Factors and Wind Deflection Warning of Transmission Lines Based on Meteorological Prediction

Transmission lines are affected by external environmental factors such as strong winds and ice cover. In recent years, extreme weather events have increased, leading to recurrent disturbances in transmission lines because of wind deflection. These incidents have resulted in significant financial losses and have disrupted regular industrial and domestic activities. In this paper, the ANSYS Workbench 2020 R2 finite element analysis platform was used to establish a transmission line-hanging insulator string system model. Calculations on transmission lines were conducted considering variations in different stall spacing, height differences, wind speed, and the wind attack angle. The impact of these diverse factors on the wind deflection of insulators was scrutinized, leading to the derivation of patterns describing how the wind deflection angle shifts in response to changes in stall spacing, height differences, wind speed, and the wind attack angle. Based on the generalized linear regression network and particle swarm improved support vector machine algorithm, a meteorological prediction-based early warning method for wind deflection of transmission lines was proposed, a transmission line wind deflection early warning model was established, and the practical effect of the model was evaluated. The outcomes of this study provide crucial data for the formulation and development of ultra-high voltage (UHV) and extra-high voltage (EHV) transmission networks. Furthermore, they can contribute to the advanced detection of wind deflection issues.

Interphase‐Designable Additive‐Enabled Ethylene Carbonate‐Free Electrolyte for Wide‐Temperature, Long‐Cycling, High‐Voltage Lithium Metal Batteries

AbstractIncreasing the upper cut‐off voltage of the LiNixCoyMn1‐x‐yO2 (NCM)‐based lithium‐metal batteries (LMBs) is highly pursued for achieving high battery energy density. However, the cycling stability of high‐voltage LMBs, which is associated with ethylene carbonate electrolytes, remains greatly challenging. Herein, an interphase‐designable additive‐enabled ethylene carbonate‐free electrolyte strategy is proposed for achieving 4.6 V Li||NCM811 battery with long cycling life from 55 to −30 °C. The solvent characteristics of ethyl methyl carbonate endow LMBs with potential merits in high voltage, wide temperature, and cycling stability, which are further strengthened by the additive, 1,5‐difluoro‐2,4‐dinitrobenzene (FNB), for optimizing electrode electrolyte interphases. The sturdy LiF‐rich and LiNxOy‐contained electrode/electrolyte interphase on cathode/anode surfaces can protect two electrodes well from electrolyte corrosion and also reduce excessive electrolyte decomposition. As expected, the Li||NCM811 batteries can maintain 70% capacity retention after 500 cycles with superior high‐temperature and low‐temperature performance (from 55 to −30 °C). The 6.8Ah pouch cells with this electrolyte can achieve a high energy density of up to 505 Wh kg−1.

Enhancing Orbital Interaction in Spinel LiNi0.5Mn1.5O4 Cathode for High-Voltage and High-Rate Li-Ion Batteries.

High voltage cobalt-free spinel LiNi0.5Mn1.5O4 (LNMO) is well organized as a high-power cathode material for lithium (Li)-ion batteries, however, the weak interaction between the 3d orbital of the transition metal (TM) ions and the 2p orbital of oxygen (O) leads to the instability of crystal structural, hindering the long-term stable cycling of LNMO cathode especially at high temperatures. Here, a design strategy of orbital interaction is initiated to strengthen TM 3d-O 2p framework in P-doped LNMO (P-LNMO) by choosing phytic acid as P dopant, which can realize more uniform doping compared to regular phosphate. The results show that the enhancement of TM 3d-O 2p orbital interaction in P-LNMO can suppress the Jahn-Teller effect and subsequent dissolution of Mn, as well as lowers the energy barrier for Li ion insertion/extraction kinetics. As a result, superior electrochemical performances including high discharge capacity, stable cycling behavior and enhanced rate capability of P-LNMO are obtained. Significantly, the P-LNMO pouch cell shows great cycling stability with 97.4% capacity retention after 100 cycles.

Mathematical modeling of rare earth element separation in electrodialysis with adjacent anion exchange membranes and ethylenediaminetetraacetic acid as chelating agent

This research delves into the effective use of electrodialysis for the separation of rare earth elements (REEs), specifically separating dysprosium (Dy) from praseodymium (Pr) and neodymium (Nd). A robust mathematical model based on the extended Nernst-Planck equation is introduced, simulating the process within a configuration that includes two adjacent anion exchange membranes. The model integrates aspects such as feed equilibrium, ion exchange within the membrane, and overall ion flux. Validation of the model's predictability was conducted through Chi-squared tests and root mean square error (RMSE) calculations, affirming its capability to accurately predict ion concentrations across different compartments. The study examines essential parameters such as applied voltage, rinse solution concentration, and feed concentration, assessing their impacts on separation performance and energy efficiency. Results indicate that higher voltages above 8 V, while speeding up separation, detrimentally impact energy use. It also highlights a critical balance in rinse solution concentration; lower concentrations below 0.05 mol/L enhance energy efficiency but may undercut separation efficacy due to early depletion. A linear correlation between the necessary rinse concentration and feed concentration was established, with higher feed concentrations demonstrating reduced specific energy consumption, thus enhancing overall efficiency. However, challenges remain in current efficiency due to the independent migration of SO42− ions in this specific setup. The findings advocate exploring alternative configurations, like alternating cation and anion exchange membranes, to optimize both environmental and economic aspects of REE separation. This study provides valuable insights and recommendations for refining electrodialysis systems in REE processing, contributing to sustainable and cost-effective electrodialysis systems.

Inhibition of Phase Transition in Amorphous Niobium Oxide by Covalent Carbon Reinforcement Enables Fast‐Charge and Long‐Duration Lithium Storage

AbstractNiobium oxides are potential anode materials for ultrafast and safe lithium‐ion batteries due to their high ionic conductivity and relatively high operation voltage. However, the electrochemically induced phase transformations that involve multi‐electron redox reactions in a wide voltage window cause rapid capacity degradation and poor rate capability. Here, a novel carbon‐covalent amorphous niobium oxide anode is reported to greatly suppress the phase transition during cycling via formation of strong Nb─O─C bonds, achieving high‐capacity, fast‐charge and long‐duration lithium storage. This amorphous structure and forming covalent carbon contribute to good volume accommodation and high electron conductivity. The carbon‐covalent amorphous Nb2O5 displays a high reversible capacity of 361.5 mAh g−1 at 0.1 A g−1 and excellent cycling stability with a capacity of 189.8 mAh g−1 at a high rate of 10 A g−1 after 9000 cycles. Structure characterizations reveal that the well‐preserved amorphous structure without phase transition during repeated Li+ insertion/desertion is responsible for the superior performance. This work opens a new avenue on rational design of high‐performance amorphous electrode materials for next‐generation batteries.

Inclusion of Anion Additives in the Inner Solvation Shell to Regulate the Composition of Solid Electrolyte Interphase

AbstractAn innovative approach to electrolyte engineering in carbonate electrolytes is introduced by incorporating high donor number dual anion additives into the conventional electrolyte system (1 M NaPF6 EC:PC). The active engagement of anions in the primary solvation shell effectively hinders the reduction of solvent molecules by reducing the Lowest Unoccupied Molecular Orbital (LUMO) of Na+‐solvent‐anion complex as compared to the LUMO of pure solvents or Na+‐solvent complex. The participation of anions leads to the formation of a thinner and an inorganic‐rich Solid Electrolyte Interphase on the hard carbon anode enhancing Initial Coulombic Efficiency and significantly improving its kinetics. Moreover, the system with dual anion additives exhibits oxidative stability up to 4.5 V, effectively mitigating the undesired side reactions at high voltage operation of the layered sodium nickel manganese oxide cathode. The addition of dual anion additives proves instrumental in suppressing structural degradation and transition metal dissolution during the long cycling performance of the layered oxide cathode in a sodium‐ion full cell. The synergistic effects of this dual anion additive added electrolyte on both the anode and the cathode ultimately ensured prolonged cycling of the sodium‐ion full cell. The electrolyte engineering approach outlined in this study opens the door to advancing next‐generation high‐voltage sodium batteries.

Detection of partial discharge patterns in hybrid high voltage power transmission lines based on parallel recognition method

Due to their specially designed structures, the partial discharge detection of hybrid high-voltage power transmission lines (HHVPTL) composed of overhead lines and power cables has made it difficult to monitor the conditions of power transmission lines. A parallel recognition method for partial discharge patterns of HHVPTLs is proposed by implementing wavelet analysis and improved backpropagation neural network (BPNN) to address the shortcomings of low efficiency, poor accuracy, and inability to parallel analysis of current partial discharge (PD) detection algorithms for HHVPTLs. Firstly, considering the non-smoothness of the partial discharge of the HHVPTLs, the wavelet packet decomposition algorithm is implemented to decompose the PD of the HHVPTL and resolve the relevant signal indicators to form the attribute vectors. Then, BPNN is implemented as a classification model. A beetle optimization (DBO) algorithm based on orthogonal contrastive learning improvement is introduced to optimize the BPNN parameters since BPNN has a slow convergence problem and fails easily into a local optimum. The proposed IDBO-BPNN is employed as the model that recognizes and analyzes the parallel partial discharge patterns of HHVPTLs. Finally, the suggested model is implemented to investigate the local discharge data of an HHVPTL in the Kaggle Featured Prediction Competition and is compared with other algorithms. The experimental results indicate that the proposed model can more accurately identify whether PDs occur in an HHVPTL and detect phases where PDs occur, with higher overall accuracy and efficiency. An excellent practical performance is achieved. The proposed model can achieve the recognition accuracy of 95.5%, which is 5.3333% higher than that of the DBO-BPNN and far more than other recognition algorithms.