Detailed three-phase circuit model for power transformers over wide frequency range based on design parameters

2012 ◽  
Vol 92 ◽  
pp. 115-122 ◽  
Author(s):  
M. García-Gracia ◽  
M. Villén ◽  
M.A. Cova ◽  
N. El Halabi
Keyword(s):  
Wide Frequency Range ◽  
Circuit Model ◽  
Power Transformers ◽  
Design Parameters ◽  
Frequency Range ◽  
Three Phase

Effects of Design Parameters on Bouncing Vibrations of a Single-DOF Contact Slider and Necessary Design Conditions for Perfect Contact Sliding

1999 ◽  
Vol 121 (3) ◽  
pp. 596-603 ◽  
Author(s):  
Kyosuke Ono ◽  
Kohei lida ◽  
Kan Takahashi
Keyword(s):  
Critical Frequency ◽  
Contact Stiffness ◽  
Damping Ratio ◽  
Wide Frequency Range ◽  
Design Parameters ◽  
Frequency Range ◽  
Elastic Impact ◽  
Spring System ◽  
Perfect Contact ◽  
Contact Slider

The general characteristics of the bouncing vibrations of a IDOF contact slider model over the surface of a harmonic wavy disk were studied both by computer simulation and theoretical analysis. The necessary design conditions for a contact slider and the surface of a disk were discussed in terms of perfect contact sliding and wear durability. It was found that the bouncing vibrations change with the amount of waviness amplitude A(fr) at the contact resonant frequency fr(=(1/2π)kc/m) relative to static penetration depth δ, or fr relative to limiting critical frequency fcl, above which the downward acceleration of the surface of a disk is larger than that of a slider due to slider load. When the contact stiffness is large enough so that δ < A(fr) (fcl < fr), the slider bounces with a large amplitude similar to an elastic impact in a wide frequency range. When the contact stiffness is small enough so that δ > A(fr) (fcl > fr), bouncing vibrations occur near the contact resonance, similar to the resonance of a nonlinear soft spring system. Here, the bouncing vibration can be completely eliminatedby increasing the contact damping ratio and decreasing the slider mass and the waviness amplitude.

scholarly journals A Simple and Efficient Method for Designing Broadband Terahertz Absorber Based on Singular Graphene Metasurface

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1351 ◽  
Author(s):  
Zhongmin Liu ◽  
Liang Guo ◽  
Qingmao Zhang
Keyword(s):  
Numerical Simulation ◽  
Efficient Method ◽  
Input Impedance ◽  
Wide Frequency Range ◽  
Circuit Model ◽  
Frequency Range ◽  
Terahertz Absorber ◽  
Relative Bandwidth ◽  
Analytical Expressions ◽  
Broadband Terahertz

In this paper, we propose a simple and efficient method for designing a broadband terahertz (THz) absorber based on singular graphene patches metasurface and metal-backed dielectric layer. An accurate circuit model of graphene patches is used for obtaining analytical expressions for the input impedance of the proposed absorber. The input impedance is designed to be closely matched to the free space in a wide frequency range. Numerical simulation and analytical circuit model results consistently show that graphene metasurface-based THz absorber with an absorption value above 90% in a relative bandwidth of 100% has been achieved.

scholarly journals Design Optimization with Geometric Programming for Core Type Large Power Transformers

2014 ◽  
Vol 6 (1) ◽  
pp. 13-18 ◽  
Author(s):  
Tamás Orosz ◽  
István Vajda
Keyword(s):  
Design Optimization ◽  
Geometric Programming ◽  
Large Scale ◽  
Cost Optimization ◽  
Power Transformers ◽  
Design Parameters ◽  
Large Power ◽  
Economic Choice ◽  
Three Phase ◽  
Solution Methods

Abstract A good transformer design satisfies certain functions and requirements. We can satisfy these requirements by various designs. The aim of the manufacturers is to find the most economic choice within the limitations imposed by the constraint functions, which are the combination of the design parameters resulting in the lowest cost unit. One of the earliest application of the Geometric Programming [GP] is the optimization of power transformers. The GP formalism has two main advantages. First the formalism guarantees that the obtained solution is the global minimum. Second the new solution methods can solve even large-scale GPs extremely efficiently and reliably. The design optimization program seeks a minimum capitalized cost solution by optimally setting the transformer's geometrical and electrical parameters. The transformer's capitalized cost chosen for object function, because it takes into consideration the manufacturing and the operational costs. This paper considers the optimization for three winding, three phase, core-form power transformers. This paper presents the implemented transformer cost optimization model and the optimization results.

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