High Frequency Voltage Research Articles

Novel 4H–SiC MESFET with high ability in gate capacitances control for high frequency applications

The ability to control the gate capacitances is crucial for high-frequency applications, as it affects the device's frequency characteristics, gain and power handling capabilities. We present a 4H–SiC metal-semiconductor field-effect transistor (MESFET) with high gate capacitance control ability for high-frequency applications. The proposed structure (GCC-MESFET) consists of a step gate and a SiC well for adjusting the channel depletion layer and modifying the channel charges. Therefore, the gate capacitances will be controlled (GCC-MESFET). The proposed structure significantly improves the cut-off frequency (fT) and maximum oscillation frequency (fmax). The fT has increased from 23.5 GHz to 33 GHz and the fmax from 50.1 GHz to 54.4 GHz in the proposed structure compared to a conventional structure (C-MESFET). The results show that the DC maximum output power density (Pmax), DC transconductance (gm), cut-off frequency (fT) and maximum oscillation frequency (fmax) of GCC-MESFET improve in comparison with a conventional structure (C-MESFET). It is necessary to mention that the drain current and the breakdown voltage of the proposed structure increase by 48 % and 20 % respectively, compared with the C-MESFET structure due to modifying the channel charges and adjusting the electric field. So, the proposed structure can be used for high current, high voltage, high-power and high frequency applications.

An integrated dual-frequency IVUS system with interleaved sampling and parallel signal processing based on FPGA

Abstract Due to the lack of high voltage and low frequency pulse transmission channels, commercial high frequency IVUS imaging system cannot meet the hardware requirements of ultrasound angiography. Therefore, it is of great research significance to develop a dual-frequency IVUS rotary imaging system with high integration, high sampling rate and sampling accuracy. In this work, an integrated dual-frequency IVUS system with interleaved sampling and parallel signal processing based on FPGA was developed. The central frequency of low-frequency channel is up to 10MHz, and the peak voltage range is 80-200V. The central frequency of the high-frequency channel is up to 60MHz, and the voltage peak-to-peak range is 40-80V. The acquisition channel is 500MHz and 12bit, which is realized by interleaved sampling of two ADC. The motor controlled ultrasonic transducer acquires 400-800 lines per turn, and eventually form a 360-degree IVUS hybrid imaging successfully.

An Improved High-Frequency Voltage Signal Injection-Based Sensorless Control of IPMSM Drives With Current Observer

An Improved High-Frequency Voltage Signal Injection-Based Sensorless Control of IPMSM Drives With Current Observer

Periodic Vortices Created by Plasma Actuator with Low Frequency

Dielectric barrier discharge plasma actuators, capable of creating a quasi-steady wall jet, are well suited for flow control over the microair vehicles at low Reynolds number. The plasma actuator is usually excited by a sinusoidal high-voltage power with a frequency of a few to tens of kilohertz. However, the investigations on the flowfield produced by a plasma actuator with a frequency below 200 Hz remain limited. Motivated by this demand, the formation and characterization of the vortices generated by a plasma actuator with a high-voltage frequency of 125 Hz are studied in detail. In addition to the starting vortex, it is of great importance that a train of vortices that shed periodically from the junction between the two electrodes and are quite different from the starting vortex are first observed. The shedding frequency of the periodic vortices is the same as the high-voltage frequency of 125 Hz. Combining the acoustic with the flow characteristics of the plasma actuator, the formation mechanism of these periodic vortices is discussed. Finally, a criterion for generating the periodic vortices is proposed based on the relationship between the scale of vortices and the separation distance between the two neighboring periodic vortices.

Spark discharge-initiated radical polymerization

A new spark discharge initiated radical polymerization (SDRP) was developed. Monomer radicals were generated by spark discharge emitted from a Tesla coil as a resonant transformer generating high frequency and high voltage, and the monomer itself acted as an initiator for propagation in polymerization at the initial stage. Poly(styrene), poly(acrylonitrile), and poly(styrene)/poly(vinyl benzoate) were successfully synthesized by the SDRP. The versatile SDRP was further developed using 2,2,6,6-tetramethylpiperidine 1-oxyl free radical (TEMPO) to create dormant species to perform nitroxide-mediated-radical-polymerization. We employed d-limonene as a solvent for the SDRP because limonene can effectively dissolve the polymers. Furthermore, solitons of polyacetylene were employed as a polymerization initiator. The solutions as a carrier in polyacetylene was generated with spark discharge. This can be referred to as "soliton-initiated polymerization".

An asymmetrical quadruple active bridge series resonant DC–DC converter for modular solid‐state transformers

AbstractThe DC–DC conversion stage of a three‐stage solid‐state transformer is the most challenging due to the combination of high power, medium voltage, and medium frequency. This combination also causes most of the losses in the DC–DC stage. To address this issue, a new asymmetrical quadruple active bridge series resonant DC–DC converter (AQAB‐SRC) has been proposed as a building block for solid‐state transformers. The converter achieves soft switching of all switches throughout the operating range by extending and using the half‐cycle continuous conduction mode control strategy. It also has fewer high‐frequency transformers compared to other converters, as more bridges are connected to the same multi‐winding transformer. The optimal design of AQAB‐SRC has been analyzed theoretically, and simulation and lab‐scale experimental results have been obtained to validate the feasibility and validity of the proposed topology.

A processable high thermal conductivity epoxy composites with multi-scale particles for high-frequency electrical insulation

The solid-state transformer (SST) in the renewable energy grid is developing in the way of high voltage and high frequency, which often results in a sharp increase in heat production of the equipment and accelerates the failure of the insulating materials. Epoxy resin (EPR) is commonly used as an insulation material for SST due to its excellent electrical insulating properties, processing performance (viscosity), and low price. However, the thermal conductivity of EPR is only about 0.2 W/(m·K), which leads to poor insulating performance under high frequency and temperature. To enhance thermal conductivity, a substantial quantity of highly thermally conductive particles is incorporated into the EPR, accompanied by a severe increase in electrical insulation defects and viscosity. This study utilized a multi-scale particle-filled approach to investigate the thermal conductivity, processing characteristics, and high-frequency electrical insulation performance of composites. The composite, filled with 25 µm BN and 5 µm SiO2 particles, enhances thermal conductivity to 0.732 W/(m·K) and demonstrates superior electrical insulating properties at both 10 kHz and 20 kHz bipolar square waves (with an increase of 131.76% and 163.97% in relative EPR, respectively), as well as good processability. Meanwhile, it is found that the dielectric loss, thermal conductivity, and electric field distribution of the composite are the main factors affecting the electrical insulating properties from 10 to 20 kHz under high voltage.Graphical

Rapid detection of incipient foil failure and remediation for longevity in repetitively pulsed, electron-beam-pumped excimer lasers for fusion research.

The use of an electron beam to pump an excimer laser has the advantage of being readily scalable to higher laser energies at high efficiency. Typically, a pulsed power driver generates the electron beam in a vacuum diode that consists of an electron emitter and a thin anode foil that holds the vacuum against the atmospheric-pressure laser gas. Even a miniscule leak in the anode foil can lead to an electrical breakdown in the vacuum diode, resulting in the destruction of the foil and evidence of the failure mechanism. The problem is even more onerous at the high voltage, high current, and pulse repetition frequencies needed for the large-area diodes used in excimer lasers for fusion research. Electra is one such laser used at the Naval Research Laboratory to develop excimer laser technologies for inertial fusion energy. To achieve longevity on Electra, it was necessary to instantly detect an incipient foil failure and halt the pulsed power drivers so the physical cause(s) could be studied. This rapid detection was accomplished using an optically filtered photodiode that senses the presence of argon emission from a Penning discharge vessel attached to the vacuum diodes. Details of this "Spectral Penning Leak Detector" device and its operation are presented. The diagnostics allowed the identification of a recurrent pinhole leak in the anode foil induced by cathode spots, which were created by electron emission from the foil during post-pulse voltage reversals. Eliminating the voltage reversals increased the continuous operation of the Electra laser from hundreds of shots to over 90 000 shots.

Improvement of AC Conditioning Effect in Vacuum by High Frequency Voltage

To improve the dielectric strength in vacuum, spark conditioning through repetitive breakdowns by AC or impulse voltage is an effective method. AC conditioning at commercial power frequencies has been widely used due to its cost‐effectiveness, but the breakdown voltage after AC conditioning is generally lower compared to impulse conditioning. We have confirmed that multiple breakdowns occur successively in a half cycle of AC voltage application. It is considered that the multiple breakdowns are harmful for conditioning and triggered due to the previous breakdown in the same half cycle. In this paper, we discuss dielectric strength improvement by high frequency AC conditioning and how the multiple breakdowns are induced. We experimentally confirmed that the AC conditioning effect is improved by increasing the frequency of AC voltage for different applied AC conditioning voltages in a sphere‐plane electrode system. We focused on the breakdown position from the light emission images during AC conditioning to investigate whether the multiple breakdowns were induced or affected by the previous breakdown. We found that the multiple breakdowns occurred close to the previous breakdown position. The multiple breakdowns would be induced by the collision of metal particles due to the previous breakdown with the counter electrode. These breakdowns do not contribute to removing protrusion and would lead to damage to the electrode surface. The increasing frequency of AC conditioning would suppress the multiple breakdowns and improve the dielectric strength in vacuum. © 2024 The Author(s). IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Vertical diamond Schottky barrier diodes with curved field plates

Diamond Schottky barrier diodes (SBDs) could theoretically operate at high voltage, high temperature, and high frequency and be potentially used in power electronics. However, the device breaks down prematurely and cannot operate stably at high voltages due to the edge electric field crowding. In this work, a vertical diamond SBD with a curved field plate (CFP) was prepared using a chemical reflow method, inductively coupled plasma etching, and electron-beam evaporation. This structure alleviates the electric field crowding at the edge of the Schottky electrode and results in a breakdown voltage and current density of 380 V and over 3000 A/cm2, respectively. After repetitive measurements, we found that the device can repeatedly breakdown at around 380 V. These results indicate that CFP structure diamond SBDs have great application in high-voltage and high-power electronic devices.

Study of LC oscillation based on excitation source of two-stage full-bridge structure

Abstract Nuclear magnetic resonance logging transmitting circuits must face the harsh operating environment of high voltage and high frequency. To reduce the voltage and current tolerated by the switching devices in the circuit and minimize the circuit loss, a high-frequency, high-voltage pulse transmitting circuit based on a two-stage full-bridge structure is designed in this paper. A new strategy for pulse excitation oscillation is proposed. The proposed strategy is based on the decision to end the excitation at the moment of peak voltage and the condition for limiting peak charging current (3.2). Finally, the circuit topology and excitation strategy proposed to achieve the overall optimal performance of sustained voltage oscillation with a peak voltage of 1180 V, precisely matching the transmitting frequency of 481 kHz and suppressing the charging current below 10 A.

Power consumption profiles of the main fans at coal mines

Purpose. To determine the main indicators of the power consumption profiles of the main ventilation fans of coal mines under the condition of regulating their performance using controlled electric drive systems based on semiconductor elements. The methods. The methods of operations research were used to analyse technological processes in terms of compliance of the actual power consumption profiles of the main fans with their expected operating modes. The methods of mathematical statistics were used to determine the statistical parameters of the electrical loading diagrams of the main ventilation fans of coal mines. Findings. A statistical analysis of typical power consumption profiles of the main fans of coal mines with different electric drive systems has been carried out: a synchronous motor with a high-voltage frequency converter, an induction motor based on the asynchronous-thyristor cascade system, and a synchronous motor with ‘classical’ rotor excitation control without semiconductor elements. The feasibility of using adjustable electric drive systems to control the performance of main ventilation fans in terms of reducing active power consumption has been confirmed. However, at the same time, the consumption of a significant amount of reactive power is shown, which is inherent for systems based on semiconductor elements, regardless of the motor type (synchronous or asynchronous). Originality. The statistical analysis of the actual daily power consumption profiles of the main fans of coal mines with different controlled electric drive systems has shown that the standard deviation of the active load does not exceed 1% of the rated power of the drive motor and does not depend on its type (synchronous or asynchronous). Practical implementation. The practical value of the work is in determining the actual consumption of reactive power by the systems of controlled electric drive based on semiconductor elements. It shows its significant level, which should be provided by appropriate filter-compensating devices on the power supply buses of the motors of the main ventilation fans.

Recent Advanced Ultra‐Wide Bandgap β‐Ga2O3 Material and Device Technologies

AbstractGallium oxide (Ga2O3) is an emerging ultra‐wide bandgap (UWBG) semiconductor material that has gained significant attention in the field of high voltage and high frequency power electronics. Its noteworthy attributes include a large bandgap (Eg) of 4.8 eV, high theoretical critical breakdown field strength (EC) of 8 MV cm−1, and saturation velocity (νs) of 2 × 107 cm s−1, as well as high Baliga figures of merit (BFOM) of 3000. In addition, Ga2O3 has the advantages of large‐size substrates that can be achieved by low‐cost melt‐grown techniques. This review provides a partial overview of pivotal milestones and recent advancements in the Ga2O3 material growth and device performance. It begins with a discussion of the fundamental material properties of Ga2O3, followed by a description of substrate growth and epitaxial techniques for Ga2O3. Subsequently, the contact technologies between Ga2O3 and other materials are fully elucidated. Moreover, this article also culminates with a detailed analysis of Ga2O3‐based high voltage and high frequency power devices. Some challenges and solutions, such as the lack of p‐type doping, low thermal conductivity, and low mobility are also presented and investigated in this review.

Parasitic-Based Model for Characterizing False Turn-On and Switching-Based Voltage Oscillation in Hybrid T-Type Converter

High frequency and high voltage switching converters utilizing wide bandgap semiconductors are gaining popularity thanks to their compactness and improved efficiency. However, the faster switching requirements gives rise to new challenges. A key issue is the increased oscillation of the drain–source voltage caused by the switching action of the complementary switch in the same phase or change of state of the other phase switches. The voltage stress caused by these oscillations can damage the switch. Furthermore, the high dv/dt during turning-on of one switch might result in false turn-on of the complementary switch due to the miller effect. In this paper, these issues are investigated in a T-type converter through analytical and experimental analysis. Based on the proposed analytical approach, simple and cost-wise solutions utilizing an optimum design of gate driver circuits and circuit layout modifications can be developed to cope with the aforementioned issues. A comprehensive analytical model of the converter with consideration of parasitic capacitances and inductances is developed. By performing sensitivity analysis on the model, the effect of the parasitic parameters on the drain–source voltage oscillation and gate–source voltage amplitude in case of false turn-on is studied. The validity of the model is then assessed through numerical simulations and experimental results.

A solid-state pulse power sub-nanosecond SiC DSRD-based generator with high-voltage and high repetition frequency for pulse discharge water treatment

Water treatment is one of the most important issues for all walks of life around the world. The unique advantages of the solid-state power electronic pulses in water treatment make it attractive and promising in practical applications. The output voltage, rising time, repetition rate, and peak power of output pulses have a significant impact on the effectiveness of water treatment. Especially in pulse electric field treatment and pulse discharge treatment, the pulse with fast rising time achieves the advantage of generating plasma without corona, which can avoid water heating effect and greatly improve the efficiency of the pulse generator. High repetition rate can significantly reduce the peak power requirement of the pulse in water treatment application, making the equipment smaller and improving the power density. Therefore, the study developed a high-voltage high frequency sub-nanosecond pulse power generator (PPG) system for wastewater treatment. It adopts SiC DSRD (Drift Step Recovery Diode) solid-state switches and realize modular design, which can achieve high performance and can be flexible expanded according to the requirements of water treatment capacity. Finally, an expandable high-voltage PPG for water treatment is built. The output parameters of the PPG include output pulse voltage range from 1 to 5.28 kV, rise time <600 ps (20%–90%), repetition up to 1 MHz. The experiment results of PPG application for pulse discharge water treatment is presented. The results indicate that the proposed generator achieves high-efficiency degradation of 4-Chlorophenol (4-CP), which is one of the most common chlorophenol compounds in wastewater. From experiment, the homemade system can degrade 450 mL waste water containing 500 mg/L 4-CP in 35 min, with a degradation rate of 98%. Thereby, the requirement for electric field intensity decreased. Through the further quantitative analysis, the impact of frequency, voltage, and electrode spacing on the degradation effect of 4-CP is confirmed.

Review Design and Simulation of a Switched Reluctance Motor Using Sensorless Control System

Abstract: This paper mainly introduces the acquisition of the position information of the switched reluctance motor through the inductance, which can make the switched reluctance motor(SRM) correct commutation. The main method is to apply highfrequency and low-duty pulse voltages to the two non-conducting phases of the switched reluctance motor when the motor is in low-speed operation, so that the non-conducting phase generates a response current through the rising slope of the response current The current change rate is obtained by the difference with the falling slope, and then the current change rate is converted into inductance through a formula, and whether the inductance reaches the inductance threshold is judged whether it reaches the commutation position, and the motor is subjected to timely and accurate commutation processing. This method is realized by matlab/simulink simulation, and combined with the high-speed inductance method obtained by the flux ratio current, to realize the position sensorless technology combined with the inductance method in the full speed cycle, and the simulation verifies that the low-speed and high-speed algorithms can be smooth Switch, and can realize its commutation control function, and It provides simulation support for applications such as lawn mower.

Detecting defects that reduce breakdown voltage using machine learning and optical profilometry

Semiconductor wafer manufacturing relies on the precise control of various performance metrics to ensure the quality and reliability of integrated circuits. In particular, GaN has properties that are advantageous for high voltage and high frequency power devices; however, defects in the substrate growth and manufacturing are preventing vertical devices from performing optimally. This paper explores the application of machine learning techniques utilizing data obtained from optical profilometry as input variables to predict the probability of a wafer meeting performance metrics, specifically the breakdown voltage (Vbk). By incorporating machine learning techniques, it is possible to reliably predict performance metrics that cause devices to fail at low voltage. For diodes that fail at a higher (but still below theoretical) breakdown voltage, alternative inspection methods or a combination of several experimental techniques may be necessary.

Development of a steady state electrothermal cosimulation model of SiC power modules

Silicon carbide power modules are suitable for high temperature, high voltage and high frequency applications. High operating temperature and high power density bring enormous challenges in chip parallel connection and junction temperature predicting. In this work, a steady state electrothermal cosimulation model is established based on Matlab electrical model and ANSYS thermal analysis model. An experimental study is conducted using a customized single die SiC module. The experimental and numerical results exhibit great agreement, with deviation consistently below 4 %. Then, comprehensive research is conducted to investigate the electrothermal performance of several dies in parallel configuration. The findings unequivocally validate the efficacy of the proposed model in accurately capturing the intricate electrical and thermal characteristics. The proposed numerical model offers a reliable and accurate electrothermal modeling approach for SiC power modules.

A Novel Phase Current Difference Construction Based Initial Rotor Position Detection Method for Surface Mounted PMSM Without Injections of High-Frequency Voltage or Pulse Sequence

A Novel Phase Current Difference Construction Based Initial Rotor Position Detection Method for Surface Mounted PMSM Without Injections of High-Frequency Voltage or Pulse Sequence

Research on Analysis and Suppression Methods of the Bearing Current for Electric Vehicle Motor Driven by SiC Inverter

The silicon carbide (SiC) inverter brings great advantages to the motor drive systems of new energy vehicles; however, severe challenges to the bearings also happen. The high dc bus voltage and switching frequency of SiC inverter can increase the discharge frequency and energy when the bearing grease film collapses. As a result, the bearing suffers severe electric corrosion, and the service life of the motor drive system can be shortened. In this paper, the characteristics of common-mode voltage and bearing voltage are analyzed, firstly under space vector pulse width modulation (SVPWM). After that, the common-mode equivalent circuit model of the motor drive system is established. The frequency characteristics of bearing voltage are revealed, and the safe working area is determined. Then, the frequency characteristics of bearing voltage and current are verified based on IGBT and SiC inverters in experiments. After that, by designing a common-mode filter, the bearing voltage and current are significantly attenuated. Furthermore, the active zero state PWM (AZSPWM) is adopted to reduce the common-mode voltage from the inverter. At the same time, combined with the common-mode filter, the bearing voltage and current are further reduced. The experimental results show that the switching frequency has a decisive effect on the amplitude of bearing voltage and current. The bearing voltage can be attenuated to around half of the reference bearing voltage by using the common-mode filter and AZSPWM strategy, respectively. The combination of the common-mode filter and AZSPWM strategy can reduce the bearing voltage to around one-fourth of the reference bearing voltage, which can effectively reduce the breakdown time and discharge energy of the grease oil film.