scholarly journals Semiconductor rectifier with side pulsation

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Evgenij Koptjaev ◽  
Jurij Dushkin ◽  
Pavel Atrashkevich
Keyword(s):  
Electromagnetic Compatibility ◽  
Cost Savings ◽  
Voltage Ripple ◽  
Three Phase ◽  
The Subject ◽  
Installation Cost ◽  
Total Voltage ◽  
Sinusoidal Function ◽  
Additional Phase Shift ◽  
Additional Phase

Described rectifier with twelve output voltage ripple is designed to supply industrial load and power lines DC, and provides savings in material and installation cost savings. A scheme managed rectifier with side pulsations, which gives a gain of up to 30% on mass and dimensions compared to classical schemes with two secondary windings are star-delta and provides better electromagnetic compatibility with the mains. The essence of the method is that the amount of segments of two sine waves results in a segment as a sinusoidal function to the amplitude and phase determined by the amplitude and phase terms. In the case of controlled semiconductor valves in a three-phase bridge circuit, it is possible to obtain an additional phase shift - at the expense of the control algorithm, which is the subject of this article. The total voltage of the two series-connected three-phase bridges (second - controlled with the "side pulsation ") connected to two secondary windings supplying three-phase transformer with a ratio of the number of turns in a ratio of 2.8: 1, respectively, and the same method of switching the two secondary windings with star connection has 12 pulsations.

Object Wave Determination by Single-Sideband Methods

1973 ◽  
Vol 31 ◽  
pp. 266-267
Author(s):  
Kenneth H. Downing ◽  
Benjamin M. Siegel
Keyword(s):  
Phase Shift ◽  
Carbon Films ◽  
Object Wave ◽  
Electron Wave ◽  
Phase Object ◽  
Heavy Atoms ◽  
Single Sideband ◽  
Thin Carbon ◽  
Additional Phase Shift ◽  
Additional Phase

Under the “weak phase object” approximation, the component of the electron wave scattered by an object is phase shifted by π/2 with respect to the unscattered component. This phase shift has been confirmed for thin carbon films by many experiments dealing with image contrast and the contrast transfer theory. There is also an additional phase shift which is a function of the atomic number of the scattering atom. This shift is negligible for light atoms such as carbon, but becomes significant for heavy atoms as used for stains for biological specimens. The light elements are imaged as phase objects, while those atoms scattering with a larger phase shift may be imaged as amplitude objects. There is a great deal of interest in determining the complete object wave, i.e., both the phase and amplitude components of the electron wave leaving the object.

Characteristics of an Electrostatic Phase Plate

1972 ◽  
Vol 30 ◽  
pp. 618-619
Author(s):  
William Krakow ◽  
Benjamin Siegel
Keyword(s):  
Phase Contrast ◽  
Objective Lens ◽  
Phase Plate ◽  
Net Charge ◽  
Phase Plates ◽  
Beam Currents ◽  
Contrast Image ◽  
Bright Phase ◽  
Additional Phase Shift ◽  
Additional Phase

Unwin has used a metallized non-conducting thread in the back focal plane of the objective lens that stops out a portion of the unscattered beam, takes on a localized positive charge and thus produces an additional phase shift to give a different transfer function of the lens. Under the particular conditions Unwin used, the phase contrast image was shifted to bright phase contrast for optimum focus.We have investigated the characteristics of this type of electrostatic phase plate, both analytically and experimentally, as functions of the magnitude of charge and defocus. Phase plates have been constructed by using Wollaston wire to mount 0.25μ diameter platinum wires across apertures ranging from 50 to 200μ diameter and vapor depositing SiO and gold on the mounted wires to give them the desired charging characteristics. The net charge was varied by adjusting only the bias on the Wehnelt shield of the gun, and hence the beam currents and effective size of the source.

Teaching Short - Circuit Calculation with Off - Nominal Turns Ratio Transformers

TEM Journal ◽  
2021 ◽  
pp. 1525-1533
Author(s):  
Allen A. Castillo ◽  
M. Natalia Galván Osuna ◽  
Norma A. Barboza Tello ◽  
Alejandra J. Vega
Keyword(s):  
Case Studies ◽  
Short Circuit ◽  
Circuit Analysis ◽  
Industrial System ◽  
Software Simulation ◽  
Three Phase ◽  
Short Circuit Calculation ◽  
The Subject ◽  
Ieee Standards ◽  
Short Circuit Analysis

Teaching short-circuit analysis is conducted primarily through case studies; however, there are not many validated short-circuit studies available on the subject, especially when considering off-nominal turns ratio transformers. In order to improve the teaching of short-circuit analysis, a three phase short-circuit study in an industrial system according to ANSI/IEEE standards by means of Zmatrix method is presented; two case studies are considered: the industrial system with nominal and offnominal turns ratio transformers, in both cases the step by step solution is given in an explicit manner and the analytical results are validated through software simulation.

scholarly journals Analysis of Input Voltage Switching Ripple in Three-Phase Four-Wire Split Capacitor PWM Inverters

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5076 ◽  
Author(s):  
Manel Hammami ◽  
Riccardo Mandrioli ◽  
Aleksandr Viatkin ◽  
Mattia Ricco ◽  
Gabriele Grandi
Keyword(s):  
Numerical Simulations ◽  
Comprehensive Evaluation ◽  
Experimental Tests ◽  
Input Voltage ◽  
Switching Voltage ◽  
Two Phase ◽  
Voltage Ripple ◽  
Battery Chargers ◽  
Three Phase ◽  
Split Capacitor

Three-phase, four-wire split capacitor inverters are currently employed in many applications, such as photovoltaic systems, battery chargers for electric vehicles, active power filters, and, in general, in all grid-tied applications that deal with possible grid voltage and/or current unbalances. This paper provides a comprehensive evaluation of the capacitor-switching voltage ripple and dc-link switching voltage ripple for the three-phase, four-wire, split capacitor inverters. Specifically, analytical formulations of the peak-to-peak and rms values of the voltage ripples are originally pointed out in this paper and determined in the case of balanced three-phase and unbalanced (two-phase and single-phase) output (ac) currents. The obtained results can help in designing the considered inverter and sizing of the dc-link capacitors. Reference is made to the sinusoidal PWM modulation and sinusoidal three-phase output currents with an almost unity power factor, representing a grid-connected application. Extensive numerical simulations have been carried out to thoroughly verify all the analytical developments presented in this paper. Furthermore, some experimental tests, having balanced output currents on the ac side, have been accomplished, validating numerical simulations and analytical developments.

Mechanism of the long-wave inertialess instability of a two-layer film flow

2008 ◽  
Vol 608 ◽  
pp. 379-391 ◽  
Author(s):  
PENG GAO ◽  
XI-YUN LU
Keyword(s):  
Free Surface ◽  
Film Flow ◽  
Underlying Mechanism ◽  
Continuity Condition ◽  
Layer Film ◽  
Long Wave ◽  
Pressure Driven Flow ◽  
Intuitive Interpretation ◽  
Additional Phase Shift ◽  
Additional Phase

This paper provides an intuitive interpretation of the long-wave inertialess instability of a two-layer film flow. The underlying mechanism is elucidated by inspecting the longitudinal perturbation velocity associated with the surface and interfacial deflections. The velocity is expressed by the composition of three parts, related to the shear stress at the free surface, the continuity condition at the interface, and the pressure disturbance induced by gravity. The effect of each velocity component on the evolutions of the surface and the interface is examined in detail. Specifically, the growth of the free surface is caused by the continuity-induced first-order velocity disturbance associated with an additional phase shift between the surface and interfacial waves, while the growth of the interface is due to the pressure-driven flow. The proposed mechanism gives an alternatively reliable prediction of the wave velocity and growth rate.

Sign in / Sign up

Export Citation Format

Share Document