scholarly journals Features stabilization of the consumer current using electro-ferromagnetic circuits

2019 ◽  
Vol 139 ◽  
pp. 01075 ◽  
Author(s):  
G.R. Rafikova ◽  
M.R. Ruzinazarov ◽  
S.K. Makhmutkhonov
Keyword(s):  
Power Factor ◽  
Distinctive Feature ◽  
Input Voltage ◽  
Load Resistance ◽  
Curve Shape ◽  
Paramagnetic Resonance ◽  
Wide Range ◽  
Electron Microscopes ◽  
Very High ◽  
Amplitude Characteristics

Electromagnetic ferromagnetic oscillatory circuits having falling sections on the amplitude characteristics formed the basis of stabilizers based on the principle of summing the currents of individual branches. A distinctive feature of such stabilizers is that the current remains unchanged both when the load resistance changes, so when the input voltage varies over a wide range. This is required by devices such as electromagnets of physical instruments, electromagnetic lenses of electron microscopes, instruments for emitting nuclear paramagnetic resonance, instruments and devices of various automation schemes, measuring and computing equipment, as well as many electrotechnological processes. Therefore, current stabilization has long attracted the attention of many researchers, and this is still one of the important problems of electrical engineering. The curve shape of the proposed current stabilizer is close to a sinusoid, the power factor is very high, since the device operates in capacitive mode.

scholarly journals Influence of Power Losses in the Inductor Core on Characteristics of Selected DC–DC Converters

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1991 ◽  
Author(s):  
Krzysztof Górecki ◽  
Kalina Detka
Keyword(s):  
Nanocrystalline Material ◽  
Input Voltage ◽  
Load Resistance ◽  
Operating Conditions ◽  
Switching Frequency ◽  
Power Losses ◽  
Boost Converters ◽  
The Core ◽  
Operation Conditions ◽  
Wide Range

The paper presents the results of a computer simulation illustrating the influence of power losses in the core of an inductor based on the characteristics of buck and boost converters. In the computations, the authors’ model of power losses in the core is used. Correctness of this model is verified experimentally for three different magnetic materials. Computations are performed with the use of this model and the Excel software for inductors including cores made of ferrite, powdered iron, and nanocrystalline material in a wide range of load resistance, as well as input voltage of both the considered converters operating at different values of switching frequency. The obtained computation results show that power losses in the inductor core and watt-hour efficiency of converters strongly depend on the material used to make this core, in addition to the input voltage and parameters of the control signal and load resistance of the considered converters. The obtained results of watt-hour efficiency of the considered direct current (DC)–DC converters show that it changes up to 30 times in the considered ranges of the mentioned factors. In turn, in the same operating conditions, values of power losses in the considered cores change from a fraction of a watt to tens of watts. The paper also considers the issue of which material should be used to construct the inductor core in order to obtain the highest value of watt-hour efficiency at selected operation conditions of the considered converters.

scholarly journals Design of an universal source for semi-automatic ac welding and induction heating

2021 ◽  
Vol 6 (1 (114)) ◽  
pp. 38-46
Author(s):  
Vladimir Burlaka ◽  
Elena Lavrova ◽  
Svetlana Podnebennaya ◽  
Vitaliy Ivanov ◽  
Serhii Burikov
Keyword(s):  
Induction Heating ◽  
Power Factor ◽  
Distinctive Feature ◽  
Source Control ◽  
Stable Operation ◽  
Technical Solution ◽  
Automatic Welding ◽  
Feed Drive ◽  
Wide Range ◽  
Small Parts

This paper proposes a circuit solution and a power source control algorithm for semi-automatic AC welding with improved energy and weight-size characteristics. A distinctive feature of the designed source is the absence of an input rectifier: welding is carried out with a high-frequency alternating current. That has made it possible to significantly reduce power losses in the source, as well as provide the possibility of implementing induction heating by connecting an inductor to the source output. Another distinctive feature of the designed source is an increased power factor and a reduced level of higher harmonics of the current consumed. The power factor of the described source reaches 0.94 against 0.5÷0.7 for sources equipped with a conventional rectifier with capacitive smoothing. The designed source's composition includes a power supply system for the wire feed drive with speed stabilization due to positive feedback on the motor current. That has made it possible to ensure the stable operation of the drive in a wide range of speeds. A model has also been developed of a flux wire welding torch containing a feed drive and a coil with a wire (up to 100 mm in diameter), placed, in order to reduce the size, in the handle of the torch. In addition to the welding function, the source makes it possible to solve the tasks related to induction heating and/or hardening of small parts; to that end, a compact inductor is connected to its output. Tests of the source showed the feasibility of the proposed ideas and circuit solutions. The dimensions of the source are 190×107×65 mm; weight, 1.4 kg; output current, up to 120 A. The proposed technical solution enables the construction of small-sized, lightweight, universal, easy-to-use power supplies for semi-automatic welding with the option of induction heating

scholarly journals Input switched closed-loop single phase SEPIC controlled rectifier with improved performances

2021 ◽  
Vol 11 (1) ◽  
pp. 1
Author(s):  
Md. Shamsul Arifin ◽  
Mohammad Jahangir Alam
Keyword(s):  
Power Factor ◽  
Closed Loop ◽  
Harmonic Distortion ◽  
Input Voltage ◽  
Input Power ◽  
Open Loop ◽  
Dc Power ◽  
Wide Range ◽  
Input Side ◽  
Flow Through

DC power supply has become the driving source for some essential modern applications. Thereby, DC power conditioning has become a significant issue for engineers. Typically used rectifiers associated with a bridge structure is nonlinear in nature. Thereby, the current at input side of the rectifier contains harmonics, which also flow through the power line. The presence of harmonics causes several interruptions and reduce power quality. In this regard, a new close loop SEPIC controlled rectifier is proposed in this paper. The conventional scheme is arranged with a rectifier connected to a DC-DC converter, which is an open loop system. Consequently, such system cannot regulate voltage at load varying condition. The proposed SEPIC controlled rectifier can regulate voltage under load varying condition for a wide range. Additionally, the performance in terms of total harmonic distortion (THD) of input current and power factor at AC side are also within satisfactory range for the closed loop configuration. The controlled rectifier has four operating phases associated with switching states and input voltage polarity. The close loop configuration also incorporates a current and a voltage loop at the feedback path. The comparative studies have been performed among the proposed closed loop construction, the open-loop structure as well as the conventional construction. The effectiveness of the proposed controlled rectifier is verified in terms of THD and input power factor considering the results obtained from simulation.

scholarly journals Power Factor Correction Insepic Converter Fed Hub Motor for Electric Vehicle

2020 ◽  
Vol 9 (4) ◽  
pp. 319-324
Keyword(s):  
Comparative Analysis ◽  
Permanent Magnet ◽  
Electric Vehicle ◽  
Power Factor ◽  
Electric Motor ◽  
Fuzzy Controller ◽  
Power Factor Correction ◽  
Input Voltage ◽  
Experimental Setup ◽  
Wide Range

The paper deals with improvingthe power factor in permanent magnet HUB motor by using Bridgeless SEPIC converter. The input voltage of the HUB motor is controlled to ensure the smooth operation of electric motor. The wide range of input voltage is demonstrated by controlling the speed of the HUB motor using fuzzy controller. Comparative analysis of SEPIC and CUK fed HUB motor is simulated for power factor correction. A SEPIC converter with power factor of 0.939 is achieved and examined with an experimental setup.

Reduction of Specimen Contamination in Electron-Beam Instruments

1976 ◽  
Vol 34 ◽  
pp. 576-577
Author(s):  
G. Lehmpfuhl ◽  
P. J. Smith
Keyword(s):  
Electron Beam ◽  
Cold Trap ◽  
Beam Diameter ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Hydrocarbon Molecules ◽  
Electron Microscopes ◽  
Combination Of Methods ◽  
Convergent Beam ◽  
Very High

Specimens being observed with electron-beam instruments are subject to contamination, which is due to polymerization of hydrocarbon molecules by the beam. This effect becomes more important as the size of the beam is reduced. In convergent-beam studies with a beam diameter of 100 Å, contamination was observed to grow on samples at very high rates. Within a few seconds needles began forming under the beam on both the top and the underside of the sample, at growth rates of 400-500 Å/s, severely limiting the time available for observation. Such contamination could cause serious difficulty in examining a sample with the new scanning transmission electron microscopes, in which the beam is focused to a few angstroms.We have been able to reduce the rate of contamination buildup by a combination of methods: placing an anticontamination cold trap in the sample region, preheating the sample before observation, and irradiating the sample with a large beam before observing it with a small beam.

TEM study of boron additions to cobalt aluminide

1988 ◽  
Vol 46 ◽  
pp. 546-547
Author(s):  
Gerald B. Feldewerth
Keyword(s):  
High Temperature ◽  
Turbine Engines ◽  
Major Drawback ◽  
University Of Missouri ◽  
Specific Strength ◽  
Aerospace Applications ◽  
Wide Range ◽  
Ordered Alloys ◽  
The University ◽  
Very High

In recent years an increasing emphasis has been placed on the study of high temperature intermetallic compounds for possible aerospace applications. One group of interest is the B2 aiuminides. This group of intermetaliics has a very high melting temperature, good high temperature, and excellent specific strength. These qualities make it a candidate for applications such as turbine engines. The B2 aiuminides exist over a wide range of compositions and also have a large solubility for third element substitutional additions, which may allow alloying additions to overcome their major drawback, their brittle nature.One B2 aluminide currently being studied is cobalt aluminide. Optical microscopy of CoAl alloys produced at the University of Missouri-Rolla showed a dramatic decrease in the grain size which affects the yield strength and flow stress of long range ordered alloys, and a change in the grain shape with the addition of 0.5 % boron.

Features of the Christian values ​​system

2004 ◽  
pp. 21-29
Author(s):  
G.V. Pyrog
Keyword(s):  
Public Opinion ◽  
Religious Beliefs ◽  
Religious Values ◽  
Direct Influence ◽  
Moral Norms ◽  
Value System ◽  
Christian Religion ◽  
Mass Consciousness ◽  
Wide Range ◽  
Very High

In domestic scientific and public opinion, interest in religion as a new worldview paradigm is very high. Today's attention to the Christian religion in our society is connected, in our opinion, with the specificity of its value system, which distinguishes it from other forms of consciousness: the idea of ​​God, the absolute, the eternity of moral norms. That is why its historical forms do not receive accurate characteristics and do not matter in the mass consciousness. Modern religious beliefs do not always arise as a result of the direct influence of church preaching. The emerging religious values ​​are absorbed in a wide range of philosophical, artistic, ethical ideas, acting as a compensation for what is generally defined as spirituality. At the same time, the appeal to Christian values ​​became very popular.

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