scholarly journals High-efficiency high-voltage class F amplifier for high-frequency wireless ultrasound systems

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0249034
Author(s):  
Kyeongjin Kim ◽  
Hojong Choi
Keyword(s):  
High Voltage ◽  
High Frequency ◽  
High Efficiency ◽  
Battery Life ◽  
Echo Signal ◽  
Correct Operation ◽  
Voltage Amplifier ◽  
Low Distortion ◽  
Harmonic Components ◽  
Class F

This paper presents a novel amplifier that satisfies both low distortion and high efficiency for high-frequency wireless ultrasound systems with limited battery life and size. While increasing the amplifier efficiency helps to address the problems for wireless ultrasound systems, it can cause signal distortion owing to harmonic components. Therefore, a new type of class F amplifier is designed to achieve high efficiency and low distortion. In the amplifier, the resonant circuit at each stage controls the harmonic components to reduce distortion and improve efficiency. Transformers with a large shunt resistor are also helpful to reduce the remaining noise in the input signal. The proposed class F amplifier is tested using simulations, and the voltage and current waveforms are analyzed to achieve correct operation with adequate efficiency and distortion. The measured performance of the class F amplifier has a gain of 23.2 dB and a power added efficiency (PAE) of 88.9% at 25 MHz. The measured DC current is 121 mA with a variance of less than 1% when the PA is operating. We measured the received echo signal through the pulse-echo response using a 25-MHz transducer owing to the compatibility of the designed class F amplifier with high- frequency transducers. The measured total harmonic distortion (THD) of the echo signal was obtained as 4.5% with a slightly low ring-down. The results show that the low THD and high PAE of the new high-efficiency and high-voltage amplifier may increase battery life and reduce the cooling fan size, thus providing a suitable environment for high-frequency wireless ultrasound systems.

Feature Extraction Based on the Multiple Harmonic Analysis of 2-Dimensional Pattern of Partial Discharge

2013 ◽  
Vol 303-306 ◽  
pp. 478-481
Author(s):  
Yu Long Gong ◽  
Jin Xi Guo ◽  
Hong Fu Guo
Keyword(s):  
Harmonic Analysis ◽  
High Voltage ◽  
High Frequency ◽  
Short Circuit ◽  
Partial Discharge ◽  
Characteristic Parameter ◽  
Electrical Equipment ◽  
Normal Operation ◽  
Harmonic Components ◽  
Insulation Breakdown

Partial discharge will cause deterioration of insulation of high-voltage electrical equipment, resulting in insulation breakdown and short circuit accident. In order to ensure the normal operation of the high-voltage equipment, it is necessary to detect partial discharge online. By using Ultra High Frequency (UHF) defection method, statistical 2-dimensional (2D) patterns of partial discharge are obtained. Extracting the envelopes of the 2D patterns, we do the harmonic analysis for patterns’ envelopes, and the harmonic components are used as a characteristic parameter for defect type’s recognition. The results show that the harmonic components can be used as characteristic parameter for defect types’ recognition. This method has the characteristics of strong real-time and simple operation.

Method of high frequency therapy at cows' mastitis during machine milking

2020 ◽  
pp. 9-12
Author(s):  
Viktor E. Lyubimov ◽  
Keyword(s):  
Dairy Cows ◽  
Electromagnetic Fields ◽  
High Frequency ◽  
High Efficiency ◽  
Environmentally Friendly ◽  
Ultrahigh Frequency ◽  
Machine Milking ◽  
High Frequency Electromagnetic Field ◽  
Milking Machine ◽  
Methods Of Treatment

Health of dairy cows ensures human health, so it is important that dairy products do not contain antibiotics that are used to treat any inflammation, including mastitis. In Russia at present, the problem of mastitis in cows exists with both attached and loose housing of cows. Mastitis of dairy cows are the great problem in milking husbandry. Losses from mastitis in milk yield can reach 15-20%. The main reasons for the occurrence of nonspecific mastitis of cows are the shortcomings of the working components of the milking machine: the degree of deterioration of the nipple rubber and the violation of machine milking technology (the reduction in pre-milking time and vacuum fluctuations account for 70% of all causes). Treatment of mastitis with antibiotics is effective, but not environmentally friendly and unacceptable. For the treatment of inflammation of the udder, it is necessary to use more environmentally friendly methods of treatment, one of which is the exposure to ultra-high frequency electromagnetic field tested by medicine. Use of three types of medical-mobile milking machines with the same method of exposure to ultrahigh-frequency electromagnetic fields on cow's nipples through electrodes in milking cups: LPDA-1-UHF, LPDA-2-UHF and LPDA-UHF-30 M, is described in the article. Author proved that cows with subclinical forms of mastitis recovered faster during milking with exposure to the ultrahigh frequency than when treated by antibiotics, and milking with the ultrahigh frequency device helps to recover 82% of the affected quarters with clinical forms and 100% of cows with subclinical forms of mastitis or with udder irritation. The high efficiency of the method of exposure to electromagnetic fields of the ultrahigh frequency during machine milking by means of medical-mobile milking machines LPDA-UHF for the prevention and treatment of mastitis of cows was shown.

Analysis and Design of 3.3 kV IGBT Based Three-Level DC/DC Converter with High-Frequency Isolation and Current Doubler Rectifier

2009 ◽  
Vol 25 (25) ◽  
pp. 103-108
Author(s):  
Dmitri Vinnikov ◽  
Tanel Jalakas ◽  
Indrek Roasto
Keyword(s):  
High Voltage ◽  
High Frequency ◽  
Power Converter ◽  
Rolling Stock ◽  
Analysis And Design ◽  
Auxiliary Power ◽  
Igbt Modules ◽  
Isolation Transformer ◽  
New Generation ◽  
Generation Power

Analysis and Design of 3.3 kV IGBT Based Three-Level DC/DC Converter with High-Frequency Isolation and Current Doubler RectifierThe paper presents the findings of a R&D project connected to the development of auxiliary power supply (APS) for the high-voltage DC-fed rolling stock applications. The aim was to design a new-generation power converter utilizing high-voltage IGBT modules, which can outpace the predecessors in terms of power density, i.e. to provide more power for smaller volumetric space. The topology proposed is 3.3 kV IGBT-based three-level neutral point clamped (NPC) half-bridge with high-frequency isolation transformer and current doubler rectifier that fulfils all the targets imposed by the designers. Despite an increased component count the proposed converter is very simple in design and operation. The paper provides an overview of the design with several recommendations and guidelines. Moreover, the simulation and experimental results are discussed and the performance evaluation of the proposed converter is presented.

Calculation-and-experimental estimation of the role of the frequency ratio in changing the endurance at two-frequency deformation modes

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 64-71 ◽  
Author(s):  
M. M. Gadenin
Keyword(s):  
High Frequency ◽  
Experimental Studies ◽  
Low Frequency ◽  
Reduction Factor ◽  
Single Frequency ◽  
Cyclic Loads ◽  
Small Ratio ◽  
Harmonic Components ◽  
Deformation Modes

The cycle configuration at two-frequency loading regimes depends on the number of parameters including the absolute values of the frequencies and amplitudes of the low-frequency and high-frequency loads added during this mode, the ratio of their frequencies and amplitudes, as well as the phase shift between these harmonic components, the latter having a significant effect only with a small ratio of frequencies. Presence of such two-frequency regimes or service loading conditions for parts of machines and structures schematized by them can significantly reduce their endurance. Using the results of experimental studies of changes in the endurance of a two-frequency loading of specimens of cyclically stable, cyclically softened and cyclically hardened steels under rigid conditions we have shown that decrease in the endurance under the aforementioned conditions depends on the ratio of frequencies and amplitudes of operation low-frequency low-cycle and high-frequency vibration stresses, and, moreover, the higher the level of the ratios of amplitudes and frequencies of those stacked harmonic processes of loading the greater the effect. It is shown that estimation of such a decrease in the endurance compared to a single frequency loading equal in the total stress (strains) amplitudes can be carried out using an exponential expression coupling those endurances through a parameter (reduction factor) containing the ratio of frequencies and amplitudes of operation cyclic loads and characteristic of the material. The reduction is illustrated by a set of calculation-experimental curves on the corresponding diagrams for each of the considered types of materials and compared with the experimental data.

scholarly journals Simulation-Based Power-Loss Optimization of General-Purpose High-Voltage SiC MOSFET Circuit Under High-Frequency Operation

IEEE Access ◽  
2021 ◽  
Vol 9 ◽  
pp. 23786-23794
Author(s):  
Abhishek Kar ◽  
Mitiko Miura-Mattausch ◽  
Mainak Sengupta ◽  
Dondee Navaroo ◽  
Hideyuki Kikuchihara ◽  
...  
Keyword(s):  
High Voltage ◽  
High Frequency ◽  
Power Loss ◽  
General Purpose ◽  
Simulation Based ◽  
High Frequency Operation
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