A Multi-frequency Input-Admittance Model of Locomotive Rectifier Considering PWM Sideband Harmonic Coupling in Electrical Railways

Author(s):  
Xiangyu Meng ◽  
Zhigang Liu ◽  
Guorong Li ◽  
Xunjun Chen ◽  
Siqi Wu ◽  
...  
Keyword(s):  
2021 ◽  
Vol 2 (2) ◽  
pp. 22-28
Author(s):  
Vasily S. LARIN ◽  
◽  
Daniil A. MATVEEV ◽  

In the first part of the article, based on the results of theoretical studies performed for a simplified transformer winding equivalent scheme, it was shown that the damping factors can be estimated from the width of the resonant peaks of the frequency responses of the module and the reactive component of the voltage at the midpoint of the equivalent scheme, as well as the active component of the input admittance and neutral current of the considered resonant scheme. In this part of the article, the practical possibility of applying the obtained theoretical relations between the damping factors and the width of resonant peaks in relation to the frequency responses of power transformer windings is considered. The results of calculations of the damping factors at the two power transformers made by using the fitting of the free component of transient voltage and by determining the width of the resonance peaks of the active component of winding neutral current and the voltage transfer function, corresponding to intermediate points of the winding. It is shown that the evaluation of the values of the winding damping factors can be performed as a byproduct of transformer condition assessment by frequency response analysis (FRA).


1973 ◽  
Vol 51 (9) ◽  
pp. 946-955 ◽  
Author(s):  
R. A. Hurd

The first three terms in the expansion of the electric field in a narrow circumferential gap in the outer wall of a coaxial waveguide have been determined. Also found is the input admittance of an infinite, coaxially fed cylindrical antenna, a quantity of interest in the theory of sleeve antennas.


Author(s):  
A J Organ

A wire mesh regenerator is studied, with one end closed and the other subject to a harmonic variation of flow. The methods of linear wave analysis are used to determine acomplex input admittance, Y, for the system. Y is the ratio of volume flow to pressure excess for a given frequency, and permits piston face pressure waveform to be determined directly in terms of prescribed velocity waveform. A computational procedure is developed for finding the pressure waveform at the closed end. Computed waveforms are presented and discussed. Energy dissipated per cycle is calculated.


2021 ◽  
Author(s):  
Ramakrishna Janaswamy

New analytical expressions and numerical results for the quality factor and directivity as well as computationally convenient expressions for the input admittance of a symmetrical biconical antenna of arbitrary length $L$ and cone angle $\theta_0$ are presented. The quality factor for a wide-angle biconical antenna is shown to very closely approach the Chu's limit of $Q = (kL)^{-1}\{1+(kL)^{-2}\}$. Numerical calculations based on the analytical formula for antenna admittance confirm the conjecture that Foster's reactance theorem remains invalid even for perfectly conducting antennas. Furthermore, the variation of directivity of a wide-angle biconical antenna is a slowly varying function of its electrical length and is shown to depart significantly from that of a thin cylindrical dipole. <br>


Author(s):  
Jorge Perez ◽  
Santiago Cobreces ◽  
Daniel Pizarro ◽  
Francisco Javier Rodriguez Sanchez ◽  
Robert Grino

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