High Frequency Voltage Research Articles

Analytical plasma impedance model of dual frequency capacitive discharges with ion dynamics

Based on a fluid simulation, an analytical equivalent circuit model was developed for collisional plasmas with dual frequency (DF) excitation. Primary focus is on a fully collisional sheath and a low frequency (LF) below the ion plasma frequency. In the analytical model, the high frequency (HF) component is expressed as a series RC circuit, which matches the classical result for the limit of single frequency radio frequency discharges. The LF circuit is expressed as a parallel RC circuit to consider the response of ions to the LF voltage. The model requires three main parameters: the magnitudes of the HF and LF voltages, which are known during discharge operation and the space and time averaged ion density, which is in general unknown and needs to be determined by other means. Explicit formulas for the calculation of the HF and LF impedances are provided. Good agreement is found between the new analytical model and the fluid simulation. It is worth noting that previously published analytical models fail to reproduce the impedances, predominantly because the dynamic ion behavior and the parallel nature of the resulting ion current in respect to the LF displacement current are not considered. A practical application of the model is the calculation of the ion density in the discharge from measured impedances. For this purpose both the LF and the HF impedances can be used. A comparison of the densities estimated from the different impedances and the average density in the simulation show again good agreement.

Experimental Investigation on Stator Impedance Affected by Magnetic Saturation and Rotor Slot used for Sensor-less IM Vector Control System with High-frequency Voltage Signal Injection

Experimental Investigation on Stator Impedance Affected by Magnetic Saturation and Rotor Slot used for Sensor-less IM Vector Control System with High-frequency Voltage Signal Injection

Diode Reverse Recovery Process and Reduction of a Half-Wave Series Cockcroft–Walton Voltage Multiplier for High-Frequency High-Voltage Generator Applications

This paper investigates the diode reverse recovery process and reduction of a half-wave (HW) series Cockcroft–Walton (CW) voltage multiplier based on the steady-state analysis for high-frequency high-voltage (HV) generator applications. The diode reverse recovery process for a multistage voltage multiplier is analyzed after the introduction of steady-state operation. The diode reverse recovery problem is the bottleneck to further increase the circuit operation switching frequency for achieving high power density and short HV pulse rise and decay times. The diode reverse recovery problem is mainly caused by the diodes in the first-stage voltage multiplier. It is suggested that the most effective and economic way to alleviate the diode reverse recovery problem is by employing diodes without reverse recovery such as silicon carbide Schottky diodes in the first stage only. The silicon carbide Schottky diode without reverse recovery needs to be used only in the first stage of the voltage multiplier to effectively mitigate the reverse recovery problems at high frequency. The 300 kHz switching frequency three-stage voltage multiplier circuit hardware prototype experimental results finally validate the analysis. A technology demonstrator of a 300 kHz 8 kW 160 kV HV generator based on the proposed hybrid silicon carbide and silicon diode solution for the HW series CW voltage multiplier is provided finally.

CMOS-Compatible MESFETs for High Power RF Integrated Circuits

Metal semiconductor field effect transistors (MESFETs) have been fabricated using a 45-nm silicon-on-insulator CMOS technology available from Global Foundries. MESFETs with gate lengths of 200 nm show good manufacturability with well-controlled run-to-run variations. The DC and RF performance of devices with different drain access lengths are compared to illustrate the design trades between high breakdown voltage and high frequency operation. Two applications of the MESFETs for RF integrated circuit design are presented. The first demonstrates integrated n-channel MOSFET-MESFET cascode amplifiers that combine the enhanced voltage operation of the MESFET with the high frequency capability of the scaled MOSFET. The resulting small-signal amplifiers demonstrate cut-off frequencies of 50 GHz when operated with supply voltages of 6 V, significantly higher than the nominal 1 V breakdown voltage of the CMOS transistors. The second application demonstrates a watt-level MESFET power amplifier integrated with a CMOS current steering digital-to-analog converter (DAC). The MESFET serves as the RF output device, while the 4-bit CMOS DAC enables average power tracking. Both examples demonstrate the design flexibility enabled by the CMOS-compatible MESFETs.

Application and evaluation of variable frequency energy-saving technology for reciprocating compressor in CBM Field

Reciprocating compressor is the most important gas transportation equipment and the most important energy consumption equipment in the CBM gathering and transportation system. The existing variable clearance volume energy saving adjustment method of reciprocating compressor has the characteristics of complex operation and poor timeliness in operation. By carrying out risk identification, developing test scheme and determining control parameters, we successfully completed power frequency high speed reciprocating compressor variable frequency test. The theoretical analysis and practical operation results show that the application of high voltage frequency converter in speed control of reciprocating compressor with high frequency is feasible. The actual controllable frequency modulation range of the reciprocating compressor motor with high frequency and high speed is 34Hz to 55Hz, the resonant frequency of compressor and main motor is 51.5Hz, and the effective energy-saving frequency regulation range is 34Hz to 45Hz. The low frequency operation has better energy saving effect, the unit consumption of gas transportation is reduced by about 3%. It can effectively improve the operation efficiency of the compressor and reduce the unit consumption of gas transportation by reasonably controlling the power frequency motor of the reciprocating compressor by the frequency converter.

Precise Extraction of Dynamic R dson Under High Frequency and High Voltage by a Double-Diode-Isolation Method

A double-diode-isolation method with low parasitic capacitance devices and reverse clamping is proposed to accurately extract the high-frequency and high-voltage dynamic on-resistance ( $R_{\mathrm{ dson}}$ ) of AlGaN/GaN high electron mobility transistor (HEMT) power devices. The response time required for the drain voltage to drop back to the on-voltage of this testing circuit can reach 100 ns, and the forward voltage drop of the isolation diode is monitored in real time using low-voltage probes. A low value constant current source is built to power the testing circuit at only several mA to avoid additional self-heating effect. With these improvements, we can obtain a test frequency of more than 1 MHz, a test voltage of more than 600 V and an accuracy of higher than 97.8% for the extraction of dynamic $\text{R}_{\mathrm{ dson}}$ .

Selection of dielectric material for producing diffuse dielectric barrier discharge plasma at atmospheric pressure

Abstract We report the effect of dielectric layer and its selection criterion to produce diffuse dielectric barrier discharge plasma at atmospheric pressure. The dielectric barriers over electrodes are used to prevent glow-to-arc transition by limiting growth of discharge current. We have analyzed the dielectric properties such as secondary electron emission, dielectric constant, dielectric thickness etc in order to get better power efficiency at breakdown. It is observed that a thin dielectric layer with high dielectric constant is suitable for lowering the breakdown voltage. During one of our experiments, planar-surface discharge plasma was produced with the use of epoxy resin dielectric-covered stripe electrodes. High-voltage high frequency signal was applied between the electrodes to produce the discharge. It is observed that the discharge remain stable & uniform in our parametric range. However, after prolonged discharge operation, degradation of dielectric layer was observed in the form of powder formation over the dielectric insulation. SEM analysis reveals that the powder contains individual as well as cluster of particles of micrometer size dimension. Such micro-particle formation may be useful for some material and biomedical applications, however in other way degraded dielectric would lead to spark formation in plasma. In this context, theoretical and experimental analysis of our results is presented in this paper.

Регулируемый привод скважинного электроцентробежного насоса на основе высоковольтного многоуровневого преобразователя частоты

Регулируемый привод скважинного электроцентробежного насоса на основе высоковольтного многоуровневого преобразователя частоты

Practical Research on VSC Prototype Based on IGBTs Serial Connected Technology

With the development of insulated gate bipolar transistor (IGBT) and pulsewidth modulation control strategy, the voltage source converter (VSC) is getting more and more popular, which can be used in high-voltage frequency converter, VSC-HVDC, FACTS, and custom power. In high voltage and high power applications, serial connection of IGBTs is a good solution to overcome the voltage limitation of the single IGBT. However, for using IGBTs in this way, a comprehensive range of issues need to be addressed, especially the static and dynamic voltage-sharing of each IGBT module. This paper presents the theoretical and practical study on how to use serial-connected IGBTs in a VSC, including adaptive dynamic voltage-balance strategy, voltage-balance circuit, power supply system, and valve vase electronics. A three-phase two-level VSC consisted of 6 arms multiplied by 12 serial-connected 3300 V IGBT modules is also developed. To test the performance of the VSC, pulse test of the one arm and inverter operation test of the whole VSC are carried out. The experimental results show that the maximum voltage imbalance is about 10%, the voltage shoots are less than 12%; and the VSC works stably, which indicates a solid foundation for industrial application.

Перераспределение токов и тепловых потерь в реверсивно-включаемом динисторе при наличии поперечного перепада температуры

AbstractThe effects of a transverse temperature gradient in reversively switched-on dynistors have been studied. Taking into account these effects is important for high-voltage frequency dynistor assemblies because of the problems of a distributed cooling of the devices. A simulation description is given for the spatial dynamics of charges and heat in dynistor chips in switching of repeated current pulses. An estimation method is suggested for calculating the maximum repetition frequency coordinated with the heatsink heatsink cooling power.

Redistribution of Current and Loss of Heat in a Reversely Switched Dynistor in the Presence of a Transverse Temperature Gradient

The effects of a transverse temperature gradient in reversively switched-on dynistors have been studied. Taking into account these effects is important for high-voltage frequency dynistor assemblies because of the problems of a distributed cooling of the devices. A simulation description is given for the spatial dynamics of charges and heat in dynistor chips in switching of repeated current pulses. An estimation method is suggested for calculating the maximum repetition frequency coordinated with the heatsink heatsink cooling power.

Electrical analysis of triboelectric nanogenerator for high voltage applications exampled by DBD microplasma

Triboelectric nanogenerator (TENG) is a natural high voltage and low frequency power source by transferring ambient motion into electrical energy. To improve the output performance of the rotary freestanding TENG (RF-TENG) with the capacitive impedance load used in high voltage field, where the dielectric barrier discharge (DBD) microplasma as an example, an efficiently and effectively electrical analysis for the whole system is explored. Firstly, a simply experimental method with 99% reliability shows the root mean square (RMS) of open-circuit voltage in our RF-TENG is around 3500-4000V and the internal capacitance is 100–130 pF with frequency from 10 Hz to 30 Hz. Then, the experiments of DBD microplasma directly driven by the RF-TENG under different conditions have been conducted and the results fit well with the simulation in discharge current and voltage. Moreover, a 10–30 folds jumping of the discharge current and real-time power have been observed. Finally, by increasing the input frequency or decreasing gas thickness, the discharge intensity and efficiency have been enhanced, meanwhile over 10 times increase on discharge power (RMS) has been achieved. This work will not only help to understand the characteristics of the microplasma at low frequency (<50 Hz) but also benefit the further researches on the directly high voltage application of the RF-TENG.

A CNTFET-C first order all pass filter

A compact, low voltage, low power and high frequency voltage mode first order all-pass-filter (APF) topology is presented using carbon nanotube field effect transistor (CNTFET) based inverting voltage buffer. The proposed resistor-less APF topology uses only one capacitor and two N-type CNTFETs. Adding one CNTFET based voltage controlled resistor to the proposed first order APF results into an electronically controlled first order APF with a tuneable frequency range between 1.913 and 40.2 GHz. The proposed circuits are potential candidate for low voltage analog applications as it uses only two transistors between its supply rails. Moreover, both the proposed topologies do not have any passive component matching constraint. The realized filter circuit performance is verified with HSPICE simulations, using well known Deng’s CNTFET model at 16 nm technology node with supply voltage of ± 0.7 V. The simulation results substantiate the theoretical predictions.

4T Analog MOS Control-High Voltage High Frequency (HVHF) Plasma Switching Power Supply for Water Purification in Industrial Applications

High-power plasma power supply is very useful for many industrial and medical applications. Plasma is generated artificially in the laboratory or industry by applying the electric or magnetic field. In this manuscript, we presented the simple 4T analog MOS control high voltage high frequency inverter circuit as a plasma power supply using modulation index technique. The presented plasma power supply operated at 25 kHz frequency and 10 kV peak to peak voltage. It generates a 0 V to 10 kV controllable electric field. The generated electric field is applied and produces plasma, which can be used for many industrial applications. A 10 kV to 5 kW plasma power supply has been practically developed based on the proposed topology and experimentally tested and, additionally, excellent output power conversion efficiency is achieved. From these results, the 4T analog MOS control high voltage high frequency (HVHF) plasma switching power supply is verified.

The synergistic effects of the micro-BN and nano-Al2O3 in micro-nano composites on enhancing the thermal conductivity for insulating epoxy resin

Epoxy resin has been widely used in electrical and electronics industries due to its excellent adhesion and insulating properties. However, the low thermal conductivity limits its application in the devices, especially under the working conditions of high frequency. In this work, the epoxy resin composites filled with binary fillers of dopamine modified micro-BN and KH550 modified nano-Al2O3 were fabricated and the thermal conductivities, dielectric losses and breakdown strengths in high frequency and electrical field of the composites were studied. A high thermal conductivity of 1.182 W m−1K−1 was realized in the composite with 22.5 wt% BN and 7.5 wt% Al2O3, which was about 700% higher than neat epoxy resin. The results of breakdown experiments in high frequency and high voltage field showed that the positive effect of the thermal conductivity increase was greater than the negative effect of the dielectric loss increase, and the notably improved breakdown time of the composite was 406% higher than that of neat epoxy. The epoxy resin composites with high thermal conductivity and excellent dielectric strength could be a potential insulating material in the electrical and electronics industries.

An Improved Partially Interleaved Transformer Structure for High-Voltage High-Frequency Multiple-Output Applications

This paper proposes an improved partially interleaved structure for high-voltage (several kV) high-frequency (several hundred kHz) multiple-output applications. The proposed transformer structure is compared with other typical structures with the leakage inductance, ac capacitance, ac resistance, and the ratio of ac-dc resistance taken into consideration. The proposed structure features lower leakage inductance, smaller ac capacitance, lower ac resistance, and lower ratio of ac-dc resistance, which is suitable for high-frequency high-efficiency applications. A planar transformer with the proposed structure was built and tested in an LCLC resonant converter, where the input voltage is 40 V, the output is 4800 V, the switching frequency is 500 kHz, the output power is 288 W, and the efficiency is 96.8%, which validates the analysis.

Automatic Tuning for Sensorless Commissioning of Synchronous Reluctance Machines Augmented With High-Frequency Voltage Injection

Sensorless control of synchronous reluctance motors (SyRMs) relies on the knowledge of the machine current-to-flux maps. Previous work demonstrated the feasibility of sensorless identification of the flux maps, performed by exciting the machine with square-wave voltage pulses at standstill, and without the need of rotor locking. The rotor position was initially estimated and then used throughout the identification, in open-loop fashion. In some cases, rotor oscillation and eventually position drift led to stop the identification before the programmed $dq$ current domain was covered entirely. In this paper, the rotor position is closed-loop tracked during the motor commissioning to counteract the occurrence of rotor movement. The hysteresis-controlled excitation voltage is augmented with an high-frequency (HF) square-wave voltage component, and the position is tracked through demodulation of the current response to such HF component. The proposed approach is experimentally verified on a 2.2-kW SyRM prototype. The results show that the $i_d, i_q$ commissioning domain is substantially extended, resulting in more accurate flux maps. Moreover, self-tuning of the method is addressed and possible causes of error are analyzed and commented.

Comparative Evaluation of a Permanent Magnet Machine Saliency-Based Drive with Sine-Wave and Square-Wave Voltage Injection

This paper improves a permanent magnet (PM) machine saliency-based drive performance based on the selection of a suitable injection signal. For the saliency-based position estimation, a persistently high-frequency (HF) voltage signal is injected to obtain a measurable spatial saliency feedback signal. The injection signal can be sine-wave or square-wave alternating current (AC) voltage manipulated by the inverter’s pulse width modulation (PWM). Due to the PWM dead-time effect, these HF voltage injection signals might be distorted, leading to secondary harmonics on the saliency signal. In addition, the flux saturation in machine rotors also results in other saliency harmonics. These nonlinear attributes cause position estimation errors on saliency-based drives. In this paper, two different voltage signals are analyzed to find a suited voltage which is less sensitive to these nonlinear attributes. Considering the inverter dead-time, a sine-wave voltage signal reduces its influence on the saliency signal. By contrast, the flux saturation causes the same amount of error on two injection signals. Analytical equations are developed to investigate position errors caused by the dead-time and flux saturation. An interior PM machine with the saliency ratio of 1.41 is tested for the experimental verification.

New parameter adjustment with spinal cord stimulation for postherpetic neuralgia treatment: A case report and literature review

Abstract Posterpetic neuralgia (PHN), a common and often severe painful condition, is a kind of refractory neuropathic pain (NP). Although the clinical treatment of PHN including pregabalin, nerve block and pulsed radiofrequency have been devoted with adequate and reasonable efforts, a proportion of people with PHN fail to obtain pain relief. Spinal cord stimulation (SCS) represents an adjustable and nondestructive procedure that considered electrical stimulation as the key mechanism for NP relief and offers an alternative treatment for PHN. SCS parameters, including amplitude, pulse width and frequency, influence the nervous system and the delivery of stimulation charge. Newly proposed stimulation methods such as high-frequency SCS and burst SCS, may offer alternative treatment for NP. In this paper, we reported a case of major pain successfully treated with SCS by adjusting the stimulation parameter and the electrode position using new stimulation method. The patient suffered from severe persistent PHN in the right upper limb area. The temporary SCS electrode was placed in the dorsal root entry zone (DREZ) area with a standard generator. Initially, we programmed the parameters at 360 Hz, 140 μs, and 1.5 V. After multiple setting adjustments with inadequate pain relief, the patient was finally programmed at 40 Hz, 120 μs, and 0.5 V. This parameter setting provided optimal pain alleviation and increased the quality of the patient's life. The visual analogue scale and Hamilton anxiety scores were decreased significantly. These scores showed no significant change during the six-month follow-up. SCS combined with dorsal root entry zone at relatively high frequency and low voltage offers a new method to treat PHN patients.

Partial Discharge Analysis in High-Frequency Transformer Based on High-Frequency Current Transducer

High-frequency transformers are the core components of power electronic transformers (PET), whose insulation is deeply threatened by high voltage (HV) and high frequency (HF). The partial discharge (PD) test is an effective method to assess an electrical insulation system. A PD measurement platform applying different frequencies was set up in this manuscript. PD signals were acquired with a high-frequency current transducer (HFCT). For improving the signal-to-noise (SNR) ratio of PD pulses, empirical mode decomposition (EMD) was used to increase the SNR by 4 dB. PD characteristic parameters such as partial discharge inception voltage (PDIV) and PD phase, number, and magnitude were all analyzed as frequency dependent. High frequency led to high PDIV and a smaller discharge phase region. PD number and magnitude were first up and then down as the frequency increased. As a result, a suitable frequency for evaluating the insulation of high-frequency transformers is proposed at 8 kHz according to this work.