High Voltage Applications Research Articles

A deep dive into SiC and GaN power devices: Advances and prospects

The development of GaN and SiC devices has been the subject of intensive research in recent years, and significant progress has been made in terms of device performance, reliability, and cost-effectiveness. However, there are still challenges to be overcome before these materials can become mainstream in power electronics. This review paper compares the properties and performance of SiC and GaN power devices, which are both wide-bandgap semiconductors that offer superior performance compared to traditional silicon-based devices. The paper discusses the material properties of SiC and GaN, including their bandgaps, thermal conductivities, breakdown voltages, and on-state resistances. The paper also compares the switching speeds and costs of SiC and GaN devices, as well as the manufacturing technologies used for these devices. The paper concludes that SiC devices are generally more suitable for high-temperature and high-voltage applications, while GaN devices are more suitable for high-frequency and high-power density applications. The review paper provides insights into the advantages and disadvantages of SiC and GaN power devices and highlights areas for future research.

Evolution, Challenges and Applications of Modern MOSFETs

As technology scales down to the nanoscale regime, MOSFETs are widely used in various applications today, which serve as key components in power supplies, amplifiers, digital circuits, and microprocessors. Their ability to control and switch high currents makes them essential in electronic devices, ranging from smartphones and laptops to industrial machinery and electric vehicles. However, traditional MOSFET designs face significant limitations due to quantum effects, increased variability, and many other issues. They are prone to overheating, which limits their power handling capability, and their switching speeds are relatively slow, leading to inefficiencies in high-frequency circuits. Furthermore, traditional MOSFETs suffer from voltage limitations and require complex driver circuits, restricting their use in certain high-voltage applications. This paper provides a focused exploration of the challenges and opportunities in designing nanoscale MOSFETs, which starts from providing a comprehensive overview of the history, differences, dilemmas, and applications of modern MOSFETs. By examining the evolution of MOSFET technology, discussing the challenges faced by designers, and exploring the wide range of applications, which aims to inspire further research, innovation, and advancements in this critical field of electronics.

A Study on Corrosion of Al-Clad Coin Cell Cases in High-Voltage Li-Ion Battery

Aluminum-coated (Al-Clad) coin cell case has long been introduced to evaluate high-voltage cathode materials and electrolytes in battery research. However, our study on graphite/LiNi0.80Co0.10Mn0.10O2 (Gr/NCM811) coin cells indicates that the Al-Clad case resulted in even worse performance than the pristine stainless steel (SS) case. Post-mortem observation finds that the Al-Clad case was severely corroded, while the SS case seems to remain intact. To understand this unusual phenomenon, the corrosion behavior of the Al-Clad cases in LiPF6 electrolyte and lithium bis(fluorosulfonyl)imide (LiFSI) electrolyte, respectively, is studied. It is shown that the coating of Al on the Al-Clad cases is not dense, allowing liquid electrolytes to permeate through and contact the underlying SS core case, forming galvanic cells between the Al coating and the SS core case. At high potentials, the galvanic cells reduce the over-potential of Al oxidation, promoting corrosion of the Al coating. As such, the Al coating does not protect the underlying SS core case, oppositely, making the corrosion of itself more severe. The results of this work reveal that to support high-voltage applications, the coating of Al on the Al-Clad cases must be dense, otherwise, it makes the corrosion worse.

Facile Strategy to Prepare Poly(ionic liquid)-Coated Solid Polymer Electrolytes through Layer-by-Layer Assembly.

The inability of solid polymer electrolytes to preserve strong mechanical strength with high ionic conductivity hinders the commercialization of lithium metal batteries (LMBs). The success of fabricating layer-by-layer (LbL)-assembled electrolytes has realized the application of flexible solid polymer electrolytes in electrochemical devices. Here, we demonstrate a rational strategy to construct solid electrolytes coated with multiple ultrathin layers of polyanions (poly(sodium 4-styrenesulfonate)) and polycations (linear poly(1-butyl-3-(4-vinylbenzyl)-1H-imidazolium chloride) (BVIC)/linear poly(PEG4-VIC)/SiO2-g-poly(PEG4-VIC)) using an LbL assembly method. Poly(ionic liquid) backbones and PEG side groups are employed to facilitate the transport of lithium ions via the segmental motion of the macromolecular matrix. The fabricated free-standing membranes exhibited good ionic conductivities of 9.03-10 × 10-4 S cm-1. Furthermore, a Li/LiFePO4 cell assembled with the LbL-membrane electrolytes exhibits an initial high discharge capacity of 143-158 mAhg-1 at 60 °C with high columbic efficiency. This approach, which combines polymer synthesis and LbL self-assembly, is an effective and facile route to fabricate solid polymer electrolyte membranes with superior ionic conductivity and mechanical robustness, which are useful for electrochemical devices and high-voltage battery applications.

Open circuit fault diagnosis for a five-level neutral point clamped inverter in a grid-connected photovoltaic system with hybrid energy storage system

Introduction. Recently, the number of high and medium voltage applications has increased dramatically. The connection between these different applications requires series-parallel combinations of power semiconductors. Multilevel converter topologies provide major advantages to these applications. In this paper, a grid-connected photovoltaic system with a hybrid energy storage system using a five-level neutral point clamped inverter is studied. Although the multilevel inverter has many advantages over the two-level inverter, it has a high probability of experiencing an open circuit fault. In this context, the five-level inverter has 24 controllable switches, one of which may experience an open circuit fault at any time. Therefore, it plays an important part in the reliability and robustness of the whole system. The novelty of this paper presents an approach to accurately detect the open circuit fault in all insulated gate bipolar transistors of a five-level neutral point clamped inverter in a photovoltaic power generation application with a hybrid energy storage system. Purpose. Before using fault-tolerant control to ensure service continuity, fault diagnosis techniques must first be used, which are the crucial phase of reliability. Methods. A detection method based on the maximum and minimum error values is proposed. These errors are calculated using the expected and measured line-to-line pole voltages. Results. The open circuit fault detection method is implemented using MATLAB/Simulink. Simulation results showed the accuracy of detecting the open circuit fault in all insulated gate bipolar transistors in a short time. Moreover, this method is adaptable to several applications and is also robust to transient regimes imposed by solar irradiation and load variations.

A Reconfigurable 7T SRAM Bit Cell for High Speed, Power Saving and Low Voltage Application

The decreasing operational voltage and scaled technology node for memory designing has widened the gap between two crucial parameters for an SRAM – delay and power. As the demand for internet of things is increasing, the need for round the clock connectivity is increasing. This mandates designing a cell with a capability to switch between low power and high speed operation. Thus, this paper presents the design of dual mode operational 7T cell that can switch between single port and dual port configuration. The proposed reconfigurable cell can operate as single port or dual port cell single ended 7T cell. The reconfigurability in the cell is realized using control signals. The noise stability of the bit cell is obtained to be 333, 333, and 470 mV for read, hold, and write modes, respectively. The robustness of the cell against temperature variation, process variation and voltage variation is also analyzed. The performance variation in each parameter will not have a dramatic impact as it is within manageable limit. Its write time is 0.14 ns, while 5 ps are required for a successful read operation. The dual port configuration of the cell supports pipelining and thus operates faster than its single port configuration.

Electrode Impact on the Electrical Breakdown of Dielectric Elastomer Thin Films.

Dielectric Elastomer Actuators (DEAs) enable the realization of energy-efficient and compact actuator systems. DEAs operate at the kilovolt range with typically microampere-level currents and hence minimize thermal losses in comparison to low voltage/high current actuators such as shape memory alloys or solenoids. The main limiting factor for reaching high energy density in high voltage applications is dielectric breakdown. In previous investigations on silicone-based thin films, we reported that not only do environmental conditions and film parameters such as pre-stretch play an important role but that electrode composition also has a significant impact on the breakdown behavior. In this paper, we present a comprehensive study of electrical breakdown on thin silicone films coated with electrodes manufactured by five different methods: screen printing, inkjet printing, pad printing, gold sputtering, and nickel sputtering. For each method, breakdown was studied under environmental conditions ranging from 1 °C to 80 °C and 10% to 90% relative humidity. The effect of different manufacturing methods was analyzed as was the influence of parameters such as solvents, silicone content, and the particle processing method. The breakdown field increases with increasing temperature and decreases with increasing humidity for all electrode types. The stiffer metal electrodes have a higher breakdown field than the carbon-based electrodes, for which particle size also plays a large role.

A Design Methodology for High-Voltage, Highly-Integrated Switched-Capacitor Power Converters, and Implementation At 48 V-12 V, 23 W/cm$^{3}$ and 93.5% Peak Efficiency

In this work a design methodology and key considerations for high-voltage and highly-integrated switched-capacitor power converters is presented. The design methodology describes the power losses in high-voltage applications, where switching losses and gate-driver losses start becoming dominant compared to fully integrated, low voltage and low power applications. The design methodology is applicable for any highly-integrated switched-capacitor topology. To verify the design methodology a 48 V-12 V ladder switched-capacitor power converter in a 180 nm SOI BCD process, with external capacitors is implemented. The floating gate-drivers and a clock controller responsible for the power switch control are also presented. The peak efficiency of the proposed power converter is measured to be 93.5 %, and 24.5 W maximum output power, resulting in a power density of 23 W/cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> .

New SOS Diode Pumping Circuit Based on an All-Solid-State Spiral Generator for High-Voltage Nanosecond Applications

New SOS Diode Pumping Circuit Based on an All-Solid-State Spiral Generator for High-Voltage Nanosecond Applications

Bandgaps of long-period polytypes of IV, IV-IV, and III-V semiconductors estimated with an Ising-type additivity model.

We apply an Ising-type model to estimate the bandgaps of the polytypes of group IV elements (C, Si, and Ge) and binary compounds of groups: IV-IV (SiC, GeC, and GeSi), and III-V (nitride, phosphide, and arsenide of B, Al, and Ga). The models use reference bandgaps of the simplest polytypes comprising 2-6 bilayers calculated with the hybrid density functional approximation, HSE06. We report four models capable of estimating bandgaps of nine polytypes containing 7 and 8 bilayers with an average error of ≲0.05eV. We apply the best model with an error of <0.04 eV to predict the bandgaps of 497 polytypes with up to 15 bilayers in the unit cell, providing a comprehensive view of the variation in the electronic structure with the degree of hexagonality of the crystal structure. Within our enumeration, we identify four rhombohedral polytypes of SiC-9R, 12R, 15R(1), and 15R(2)-and perform detailed stability and band structure analysis. Of these, 15R(1) that has not been experimentally characterized has the widest bandgap (>3.4 eV); phonon analysis and cohesive energy reveal 15R(1)-SiC to be metastable. Additionally, we model the energies of valence and conduction bands of the rhombohedral SiC phases at the high-symmetry points of the Brillouin zone and predict band structure characteristics around the Fermi level. The models presented in this study may aid in identifying polytypic phases suitable for various applications, such as the design of wide-gap materials, that are relevant to high-voltage applications. In particular, the method holds promise for forecasting electronic properties of long-period and ultra-long-period polytypes for which accurate first-principles modeling is computationally challenging.

An improved method for monitoring the junction temperature of 1200V / 50A IGBT modules used in power conversion systems

Abstract Insulated gate bipolar transistor (IGBT) is one of the most used devices for high-power-density and high-voltage applications such as wind turbines, electric vehicles, and smart grids. However, the field of IGBT research is still in its infancy owing to the failures that can happen to the module due to its temperature rise. Hence, the junction temperature T j measurement of the active region is essential for analyzing and predicting the degradation state of the IGBT device. In this paper, an overall study, including uses of the governing thermal equation to estimate the junction temperature T j, experimental analysis of the IGBT component during operation, and a numerical finite element (FE) study, was conducted. The thermal management FE model is conducted to predict temperature variation along time and heat spreading inside the IGBT layers. To investigate the material’s properties and structure change during operation impacting the junction temperature, scanning electron microscopy (SEM) and energy X-ray dispersive spectroscopy (EDS) were performed on the IGBT power module. Results were used to interpret the difference between the experimental and the predicted temperature values. For effectiveness validation purposes, results obtained from the proposed FE model are compared with the results of the experimental thermo-sensitive electrical parameters (TSEP) method. Good agreement was found between the experiment and the proposed FE model.

Electrical Characterization of Multi-Gate MOSFET with Reduced Short-Channel Effects for High-Power Applications

The double-gate MOSFET is proposed for high-voltage and high-power applications with decreased short-channel effects (SCEs) and drain current with gate overlap. This model explicitly incorporates the SCEs for thin-layered MOSFETs with large drain regions. The device’s short-channel effects are decreased through the drain-resistance effect present in the device. The gate contact overlapped region significantly affects the device operation for high-voltage FETs. These effects are modeled by self-consistent solutions of available multigate MOSFET device models with potential distribution. The demonstrated model can be further applied for size limitations in the modeling of multigate MOSFETs.

Fibre Bragg Grating Sensors for Condition Monitoring of High-Voltage Assets: A Review

The high-voltage (HV) assets in the existing power transmission network will experience increased electrical, thermal, environmental and mechanical stresses and, therefore, robust condition monitoring is critical for power system reliability planning. Fibre Bragg grating (FBG) sensors offer a promising technology in HV applications due to their immunity to electromagnetic interference and multiplexing capability. This paper reviews the current technology readiness levels of FBG sensors for condition monitoring of transformers, transmission lines, towers, overhead insulators and power cables, with the aim of stimulating further development and deployment of fibre-based HV asset management systems. Currently, there are several reported cases of FBG sensors used for condition monitoring of HV assets in the field, proving their feasibility for long-term use in the power grid. The review shows that FBG technology is versatile and can facilitate multi-parameter measurements, which will standardise the demodulation equipment and reduce challenges with integrating different sensing technologies.

Polypropylene nanocomposites doped with carbon nanohorns for high-voltage power cable insulation applications

Polypropylene nanocomposites doped with carbon nanohorns for high-voltage power cable insulation applications

Analysis of Pesticide Residues on Fruit Using Swab Spray Ionization Mass Spectrometry.

The vast quantity and high variety of pesticides globally used in agriculture entails considerable risks for the environment and requires ensuring the safety of food products. Therefore, powerful analytical tools are needed to acquire qualitative and quantitative data for monitoring pesticide residues. The development of ambient ionization mass spectrometry methods in the past two decades has demonstrated numerous ways to generate ions under atmospheric conditions and simultaneously to reduce the need for extended sample preparation and circumvent chromatographic separation prior to mass analysis. Swab spray ionization enables the generation of ions directly from swabs via the application of high voltage and solvent flow. In this study, swab sampling of fruit surfaces and subsequent ionization directly from the swab in a modified electrospray ion source was employed for the screening and quantitation of pesticide residues. Aspects regarding sample collection, sampling efficacy on different surfaces, and swab background are discussed. The effect of solvent composition on pesticide-sodium adduct formation and the suppression of ionization by the background matrix have been investigated. Furthermore, a novel approach for the quantitation of pesticide residues based on depletion curve areas is presented. It is demonstrated that swab spray ionization is an effective and quick method for spectral library-based identification and the quantitative analysis of polar contact pesticide residues on food.

Linearity improvement in graded channel AlGaN/GaN HEMTs for high-speed applications

AlGaN HEMTs are popular devices for high-frequency applications. At higher frequencies, nonlinearity effects are major concerns and need serious attention. In this work, we have attempted to improve the linearity performance of graded channel Al x Ga1−x N/GaN HEMTs in comparison with abrupt channel GaN HEMTs through Technology Computer Aided (TCAD) simulation. In graded channel HEMTs, linearly grading of Al composition in the AlGaN layer, reduces the local carrier densities and provides improvement in the carrier saturation velocity. This provides an avenue to improve the overall linearity performance. A complete set of figures of merits (FOMs) such as and for both devices are presented. The simulation results have been calibrated with reported experimental results available in the literature. The graded devices are observed to have better transconductance (g m ) and drain current for gate voltages greater than −2 V. The drop in g m is reduced by nearly 50% at the higher gate-to-source voltages. Moreover, the RF figure of merits such as the current gain cutoff frequency (f T) and a maximum frequency of oscillation (f max) have been calculated for both devices. Due to the graded channel f T increases by 20% and f max becomes twice which makes it a better choice for high-voltage and high-power applications. The impact of interface trap and leakage current performance on the graded channel device are also reported. The cutoff frequency reduces by 25% with an increase in trap charge concentration from 9e17 cm−2 to 1e19 cm−2. Also, it has been found that the graded channel device shows better linearity and lower intermodulation distortion in comparison to the abrupt device which has been calculated from the linearity parameters. The high gate leakage current in the case of the graded channel device can be reduced by adding a thin GaN cap layer on the AlGaN channel which can be a future prospect of improving the performance of the graded GaN device.

Tracking Resistance in Polymeric Insulation Materials for High-Voltage Electrical Mobility Applications Evaluated by Existing Test Methods: Identified Research Needs.

With the increasing electrification of the transportation and mobility sectors, polymer insulation materials are inevitably exposed to harsher environments, including exposure to contamination, wide temperature ranges, operation at higher voltages and switching frequencies, and low-pressure environments. This paper reviews the tests to characterize the polymeric materials used in insulation systems for electric mobility applications, focusing on resistance to tracking. This paper also reports on the limitations of existing standard test methods and identifies the challenges and research needs to meet the increasing demands of the electric mobility industry. To this end, an evaluation of the scientific and technological state of the art is carried out through the analysis of theses, research articles, technical reports, manufacturers' datasheets, international standards, and white papers.

High-performance triboelectric nanogenerator based on theoretical analysis and ferroelectric nanocomposites and its high-voltage applications

With the growing economy and technology, disease prevention and individual health are becoming more and more important. It is highly urgent to develop a non-toxic, self-powered, and safe high-voltage power source to prevent diseases spread by mosquitoes, especially in isolated or remote areas. Herein, we reported a high-performance rotary triboelectric nanogenerator (R-TENG) based on customized theoretical simulations and a ferroelectric nanocomposite intermediate layer. The customized theoretical simulations based on gradient electrode gaps were established to optimize gap angles and segment numbers of the electrodes, which could prevent air breakdown and enhance the R-TENG output energy by at least 1.5 times. Meanwhile, the electrical output performance of the TENG was further enhanced with a highly oriented BaTiO₃ (BTO) nanoparticles intermediate layer by about 2.5 times. The open-circuit voltage of R-TENG reached more than 6 kV and could continuously light 3420 LEDs or 4 serially connected 36 W household fluorescent lamps. Therefore, a self-powered high-voltage disease prevention system is developed based on the high-performance R-TENG to reduce the risk of disease transmission. This work provides a prospective strategy for the further development of TENGs and expands practical applications of self-powered and high-voltage systems.

Extension of OCC Controller for High-Voltage-Gain PFC Applications

Single-stage single-switch power factor correction (PFC) rectifiers for high output voltage applications are investigated. Considerations for selecting a power stage for high-gain PFC are suggested and discussed. Accordingly, several candidate topologies for high-step-up DC/DC converters are identified and overviewed. A modified PFC OCC control scheme with extended capabilities is suggested to control the proposed high step-up PFC rectifiers. The proposed controller provides a simple and low-cost solution that can accommodate a wide range of rectifiers. Theoretical analysis is supported by simulation and experiments.

A Scalable Matrix Integrated Transformer With Controllable Leakage Inductance for a Bi-Directional Resonant Converter

Integrated transformer with built-in leakage inductors is a good approach for simplifying the whole system, as it integrates discrete leakage inductors into the transformer with printed circuit board (PCB) windings for a single-phase CLLC (1PCLLC) resonant converter. The EI-core-based integrated transformer can integrate adjustable leakage inductance into the transformer. Series or parallel connections of EI-core-based integrated transformers offer a possible solution for high-voltage and high-power applications: however, the penalty of more considerable core loss by the induced leakage flux is problematic. This paper proposes a matrix integrated transformer with controllable leakage inductance for a 1PCLLC resonant converter. Three EI-core-based elemental integrated transformers can be integrated into one three-UI-core-based integrated transformer with built-in leakage inductance, and the benefits of evenly distributed flux inside the core and much-reduced core loss can be achieved. An asymmetrical winding structure and asymmetrical core structure were proposed to adjust the built-in leakage inductance for the proposed matrix integrated transformer. An 11-kW 1PCLLC resonant converter for 800-V onboard-charger application was built to verify the proposed novel matrix integrated transformer. The designed converter can achieve a power density of 250W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> power density and 98.4% peak efficiency.