scholarly journals Parameter Analysis on Torque Stabilization for the Eddy Current Brake: A Developed Model, Simulation, and Sensitive Analysis

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Quan Zhou ◽  
Xuexun Guo ◽  
Gangfeng Tan ◽  
Xiaomeng Shen ◽  
Yifan Ye ◽  
...  
Keyword(s):  
Eddy Current ◽  
Model Simulation ◽  
Influencing Factor ◽  
Parameter Analysis ◽  
Rotating Speed ◽  
Cross Section Area ◽  
Torque Generation ◽  
Braking Torque ◽  
Stability Indexes ◽  
The Stability

Eddy current brake (ECB) is an attractive contactless brake whereas it suffers from braking torque attenuation when the rotating speed increases. To stabilize the ECB’s torque generation property, this paper introduces the concept of anti-magneto-motive force to develop the ECB model on the fundamental of magnetic circles. In the developed model, the eddy current demagnetization and the influence of temperature which make the braking torque attenuation are clearly presented. Using the developed model of ECB, the external and internal characteristics of the ECB are simulated through programming byMATLAB. To find the sensibility of the influences on ECB’s torque generation stability, the stability indexes are defined and followed by a sensibility analysis on the internal parameters of an ECB. Finally, this paper indicates that (i) the stability of ECB’s torque generating property could be enhanced by obtaining the optimal combination of “demagnetization speed point and the nominal maximum braking torque.” (ii) The most remarkable influencing factor on the shifting the demagnetization speed point of ECB was the thickness of the air-gap. (iii) The radius of pole shoe’s cross section area and the distance from the pole shoe center to the rotation center are both the most significant influences on the nominal maximum braking torque.

Stability-Optimized Clearance Configuration of Fluid-Film Bearings

2006 ◽  
Vol 129 (1) ◽  
pp. 106-111 ◽  
Author(s):  
Koichi Matsuda ◽  
Shinya Kijimoto ◽  
Yoichi Kanemitsu
Keyword(s):  
Fourier Series ◽  
Load Capacity ◽  
Fluid Film ◽  
Eccentricity Ratio ◽  
Rotating Speed ◽  
Fluid Film Bearings ◽  
Wide Range ◽  
Jeffcott Rotor ◽  
The Stability ◽  
Frequency Ratios

The whirl instability occurs at higher rotating speeds for a full circular fluid-film journal bearing, and many types of clearance configuration have been proposed to solve this instability problem. A clearance configuration of fluid-film journal bearings is optimized in a sense of enhancing the stability of the full circular bearing at high rotational speeds. A performance index is chosen as the sum of the squared whirl-frequency ratios over a wide range of eccentricity ratios, and a Fourier series is used to represent an arbitrary clearance configuration of fluid-film bearings. An optimization problem is then formulated to find the Fourier coefficients to minimize the index. The designed bearing has a clearance configuration similar to that of an offset two-lobe bearing for smaller length-to-diameter ratios. It is shown that the designed bearing cannot destabilize the Jeffcott rotor at any high rotating speed for a wide range of eccentricity ratio. The load capacity of the designed bearings is nearly in the same magnitude as that of the full circular bearing for smaller length-to-diameter ratios. The whirl-frequency ratios of the designed bearing are very sensitive to truncating higher terms of the Fourier series for some eccentricity ratio. The designed bearings successfully enhance the stability of a full circular bearing and are free from the whirl instability.

A new high-torque retarder based on combined effects of magnetorheological fluid and eddy current

2018 ◽  
Vol 30 (2) ◽  
pp. 256-271 ◽  
Author(s):  
Hui Huang ◽  
Shumei Chen ◽  
Cheng Wang
Keyword(s):  
Eddy Current ◽  
Material Selection ◽  
Magnetorheological Fluid ◽  
Experimental Result ◽  
Element Analysis ◽  
Operating Concept ◽  
Braking Torque ◽  
High Torque ◽  
The Magnetic Field ◽  
Excitation Circuit

In this article, a new high-torque retarder combining the effects of magnetorheological fluid and eddy current is researched. The new retarder provides a part of the braking torque generated by the shear stress of the magnetorheological fluid and an additional braking torque generated by the effect of the eddy current on the rotors. This operating concept is realized by a common magnetic excitation circuit generated by a new structure with several separated coils. The configurations and design details of the new retarder, including the structure, material selection, and magnetic circuit, are discussed. The mathematical models of braking torque caused by the magnetorheological fluid and eddy current are also derived. Then, a finite element analysis is performed to verify the magnetic field design of the new retarder. Finally, a prototype is fabricated, and the relevant parameters are tested. The experimental result shows that the new retarder provides not only a stable braking torque at low speed but also a great increment of braking torque varied with rotation speed, which effectively improves the total braking torque compared with conventional magnetorheological retarders.

scholarly journals A Novel Approach on the Unipolar Axial Type Eddy Current Brake Model Considering the Skin Effect

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1561
Author(s):  
Hery Tri Waloyo ◽  
U Ubaidillah ◽  
Dominicus Danardono Dwi Prija Tjahjana ◽  
Muhammad Nizam ◽  
Muhammad Aziz
Keyword(s):  
Correction Factor ◽  
Eddy Current ◽  
High Speed ◽  
Skin Effect ◽  
Actual Condition ◽  
Average Error ◽  
Low Speed ◽  
Novel Approach ◽  
Calculation Results ◽  
Braking Torque

The braking torque mathematical modelling in electromagnetic eddy current brake (ECB) often ignores the skin effect that occurrs during operation. However this phenomenon can not be simply neglected. Therefore, this paper presents a mathematical model of braking torque for a unipolar axial type of ECB system with a non-magnetic disk, which considers the skin effects. The use of mathematical models that consider the existence of skin effects is significant in approaching the braking torque according to the actual condition. The utilization of generic calculations to the model of the ECB braking torque leads to invalid results. Hence, in this paper, the correction factor was added to improve the braking torque calculation as a comparator to the proposed equation. However, the modification and addition of the correction factor were only valid to estimate the low-speed regimes of torque, but very distant for the high-speed condition. From the comparison of calculated values using analytical and 3D modelling, the amount of braking torque at a low speed was found to have an average error for the equation using a correction factor of 1.78 Nm, while after repairing, a value of 1.16 Nm was obtained. For the overall speed, an average error of 14.63 Nm was achieved, while the proposed equation had a small difference of 1.79 Nm. The torque difference from the calculation results of the proposed model with the measurement value in the experiment was 4.9%. Therefore, it can be concluded that the proposed equation provided a better braking torque value approach for both low and high speeds.

Raman Spectroscopic Study of Ba2+-Surfactant Interactions in Aqueous Monodisperse Alkylpolyoxyethylene Surfactant Solutions

1993 ◽  
Vol 47 (11) ◽  
pp. 1784-1787
Author(s):  
Diana C. W. Siew ◽  
Ralph P. Cooney ◽  
Michael J. Taylor
Keyword(s):  
Conformational Changes ◽  
Influencing Factor ◽  
Difference Spectroscopy ◽  
Raman Spectroscopic ◽  
Chain Component ◽  
Raman Spectroscopic Study ◽  
Surfactant Solutions ◽  
Surfactant Complex ◽  
Surfactant Interactions ◽  
The Stability

Aqueous monodisperse alkylpolyoxyethylene surfactant-Ba2+ systems were investigated to clarify the coordination effects between the polyether chain and the cation which have been previously identified in polydisperse alkylphenoxy- and alkypolyoxyethylene surfactant systems. The coordination effects are simplified in the present study due to the presence of only a single polyether chain component. Formation of the surfactant complex resulted in conformational changes of the polyether chain which were monitored by Raman difference spectroscopy and curve fitting. The present studies confirm that surfactant-complex formation is dependent upon the polyether chain adopting the TGT-TĜT conformation and that the stability of the complex increases with the number of filled chain sites. The length of the polyether chain is also an influencing factor.

Investigation on Eddy Current Braking Systems – A Review

2014 ◽  
Vol 592-594 ◽  
pp. 1089-1093 ◽  
Author(s):  
G.L. Anantha Krishna ◽  
K.M. Sathish Kumar
Keyword(s):  
Permanent Magnet ◽  
Eddy Current ◽  
Eddy Currents ◽  
Adhesion Force ◽  
Field Application ◽  
Train Control ◽  
Braking System ◽  
Braking Torque ◽  
Wave Forms ◽  
Transportation Applications

The changing magnetic field will induce eddy currents in the conductor. These currents will dissipate energy in the conductor and generate drag force. It is found that Aluminium is the best material as conductor compared to Copper and Zinc. Also, it is found that the larger thickness of disc, more number of turns of electromagnet and higher electrical conductivity of conductor influences the generation of greater braking torque. Conventional braking system relies on adhesion force between rail and wheel. It is found that a brake built up from permanent magnet pieces that combine both magnetic rail brake and eddy current brake permits the most profitable braking action through the whole range of acceptable speeds. Permanent magnet eddy current brake uses Neodymium - Iron - Boron (NdFeB) magnets. The analysis of permanent magnet eddy current shows that the parallel magnetised eddy current topology has the superior braking torque capability. In electrically controlled eddy current braking system subjected to time varying fields in different wave forms, the triangular wave field application resulted in highest braking torque. Electromagnetic brakes were found to interfere with the signalling and train control system. Permanent magnet eddy current brakes are a simple and reliable alternative to mechanical or electromagnetic brakes in transportation applications. Greater the speed greater is the eddy current braking efficiency. Hence, author intends to work on the development and investigation of permanent magnet eddy current braking system.

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