Eddycurrent couplings are becoming popular devices for speed and torque control. However, unlike friction brakes, in which the drag force that stops the moving object is provided by friction between two surfaces pressed together, the drag force in an eddy current brake is an. The coating thickness for rus coppercoated rods shall not be less than 0. Efficiency of these couplings depends on the excitation level. A sourcebook for industry v capacitor a device, the primary purpose of which is to introduce capacitance into an electric circuit. For eddy current coupling motor as motor users for direct current dc motor users for prospective ipm motor users proposal for inverter control do you want to improve the existing machinery. Eddy current clutch as well as fan coupling with eddy current clutch. The variable speed drive shall be an eddy current coupling type magnetic drive, of aircooled open type construction. Cable design for fair sis 300 a passion for discovery. Heenandynamatic eddy current coupling wcs 2193 and digital control ec 2000 to be equipped in s elf prop ll dtraction load car of cap 75 kn for testing of agricultural tractors. Eddycurrent probe design 175 channel if the detection channel is not perfectly orthogonal to the liftoff. Eddy current theory 1 generation of eddy currents by means of an ac field. Codecasa dipartimento di ingegneria industriale universita degli studi di padova via gradenigo 6a, 351 padova, italy email.
Eddy current clutch working, application, advantages and. Watercooled couplings wcs couplings eddy current coupling. The eddy current coupling usually consists of three basic members. Eddy current probes are particularly suitable devices for noncontact measurements on metallic targets. The method has been used successfully to detect prestressing wire failures in pccp. Is it costeffective to replace old eddy current drives. Boundary elements, eddy current problem, fi nite elements. In the nonsource, non eddy conductor region, since.
Electric motor characteristic curves with and without fluid coupling. Pdf a threedimensional magnetic field analytical model of axialflux. Eddy current clutch working, application, advantages and disadvantages mecholic no comments eddy current clutches or eddy current slip coupling are available in a broad range of sizes and speed up to thousands of kilowatts in both vertical and horizontal configurations. Similarly, the filaments couple via the periphery to yield a current. Modelling and design of an eddy current coupling for slipsynchronous permanent magnet wind generators december 2012 iv acknowledgements. Mainly this system is purely based on faradays laws of electromagnetic induction and lenzs law. An eddy current brake, also known as an induction brake, electric brake or electric retarder, is a device used to slow or stop a moving object by dissipating its kinetic energy as heat. With the new tx series, eddylab is introducing a fully digital device incorporating usb, can and a highspeed analogue interface. Results and discussion the phase sensitivity, which is defined as the phase change for a given amount of change in the eddy current amplitude, as a function of the eddy current time constant is calculated for waveforms with varying. First, the eddy current coupling loss of composites with rectangular cross section was calculated using an anisotropic continuum description based on a block model with different effective resistivities in each block.
Eddy currents also called foucaults currents are loops of electrical current induced within. An induction heater consists of an electromagnet and an electronic oscillator that passes a highfrequency alternating current ac through the electromagnet. However, the analytical modelling of the eddy current coupling is complex. Convair div national aeronautics and space administration. Eddy current inspection ection transformer analotransformer analo g when two coils are coupled by a magnetic field, they are subject to yp w e wo co s e coup ed by g e c e d, ey e subjec o the effects of a mutual inductance. There is no mechanical linkage between input and output members of the drive.
A complete schematic of a three turn, two layer spiral with the loss 48 mechanisms modeled all coupling coefficients not shown 21. Advantages of the eddy current method high testing speed high test throughput easy to automate 100% testing objective results evaluation high reproducibility documentation and recording of test results no contamination by coupling liquids areas of application for the eddy current method eddy current testing for safe components 100. Major technical parameters of eddy current dynamometer. A more detailed analysis 4 shows that the secondorder lift off is orthogonal to the firstorder liftoff and, therefore, has a component in the signal channel. Nanomagnetic s tructures for i nductive c oupling and s.
This is an electric braking system which works on the principle that eddy current produced in it opposes the driving torque. Department of energys does advanced manufacturing office amo with support from the copper development association cda. An improved structure for axialflux eddy current couplings with combined rectangleshaped magnets is proposed to minimize cogging torque without sacrificing torque density. So the torque can be measured by the dynamometer rotating torque i. Seminar on eddy current brake report pdf download abstract this is an electric braking system which works on the principle that eddy current produced in it opposes the driving torque. Eddy current is the swirling current produced in a conductor, which is subjected to a change in magnetic field. Apr 27, 2017 homework statement i have a really simple question, state two types of eddy current couplings and state a flexible coupling, but ive been googling it for the last half an hour and cant find an answer.
In addition, this paper calculated eddy current power loss, and proposed specific programs to reduce the eddy current power loss. Coupled electromagneticthermal analysis of a ferrite core electronic planar transformer. This is often also referred to as electromagnetic braking. Eddycurrent coupling with slotted conductor disk request pdf. Eddycurrent coupling with slotted conductor disk hamideh k. Coupled mechanical and electromagnetic modeling of eddy current sensors vii international conference on computational methods for coupled problems in science and engineering coupled problems 2017 n. Eddy current modeling fo r a one layer, three turn spiral showing 46 the coupling coefficients between the different inductors 20. This paper presents different analytical and numerical approaches devoted to the analysis and design of axial eddycurrent couplers. Indeed, these currents are exactly the same as the. The coating thickness for zinccoated rods shall not be less than 0. Since 1968, he has as sumed several international assignments.
Pdf eddy current loss calculation and thermal analysis of axial. This opposing torque is used to brake the automobiles. Eddy current inspection methods university of houston. The analytical model solves the multiphysics coupling analysis problem of pm eddy current couplings, and provides a fast and accurate calculation method to perform electromagneticthermal coupling. Electrostatic, magnetostatic, eddy current and magnetic transient. The work of the following section applies to the work of.
In this study the possibility of using an eddy current coupling as the slip permanent. I would like to thank my fellow students and the technical staff of the electrical. The mathematical model consists of the standard eddy current equations in the frequency domain. In this video i use lenz law to explain how eddy currents form when a piece of metal passes through a magnetic field. Rajendran coupled mechanical and electromagnetic modeling of eddy current sensors nidhal. The variable speed output shaft is rotated by the constant speed a.
Coupled electromagnetic and thermal analysis of ferrite. This paper presents different analytical and numerical approaches devoted to the analysis and design of axial eddy current couplers. In ac power systems, electric current flowing in the conductor changes direction 120 times per second for 60hz and 100 times per second to 50hz systems. Eddy current clutches or eddy current slip coupling are available in a broad range of sizes and speed up to thousands of kilowatts in both vertical and horizontal configurations.
This paper deals with analytical model extraction and also optimization of the doublesided pm axial eddycurrent couplers, which are one of the bestknown couplers used in. Study on the eddy current loss characteristic of the coaxial. Is it costeffective to replace old eddycurrent drives. An eddy current drive system consists of ac motor and eddy current coupling, a control and operators control station. Consequently, in addition to selecting the class of coupling required synchronous, eddy current, or hysteresis, the coupling type also needs to be specified. Eddy current coupling with slotted conductor disk hamideh k. Eddy current techniques in ndeeddy current techniques in.
Eddy current brakes seminar report pdf seminar topics. A complete schemati c of a three turn, two layer spiral with a 49. Since the eddycurrent clutch is a torque transmitter, it. Matrix coupling current loss this is an eddy current loss, due to coupling currents induced in a current loop that includes the superconducting nbti.
The function of an eddy current clutch is to transmit a controlled torque from the induction motor,prime mover to the load driven machine. Design optimization of an axialfield eddycurrent magnetic coupling. Fast iterative solution of eddy current problems by a 3 d. If a flaw in the conductive material disturbs the eddy current circulation, the magnetic coupling with the probe is changed and a defect signal can be read by measuring the coil impedance variation.
Electromagnetic coupling an overview sciencedirect topics. Drive source international dsi is the worlds leading manufacturer of eddy current adjustable speed drives, brakes and controls. Gear coupling selection procedure table 1 torque and horsepower ratings. This results in a high degree of cushioning between the drive system and load, permitting longer life for the machinery involved. Modeling and design the composite approach is modeled for high permeability, and low loss at the desired frequency of operation. Eddy currents in the alcator tokamak pure aanmelden. The metal matrix then sees a current parallel to the applied field of amplitude. Eddy current drive is a combination of a constant speed ac induction motor, coupled to an eddy current clutch.
The work of this section includes providing eddy current variable speed drive units with controls, couplings, accessories and spare parts. The key component of the eddy current separator is the magnetic rotor, which has a series of permanent rare earth magnets mounted on a support plate attached to a shaft. Eddy currents in the alcator tokamak citation for published version apa. Modelling and design of an eddy current coupling for slip. Lamperth hybrid power research group, department of mechanical engineering, imperial college london, london sw7 2az, u. Eddy current techniques for nondestructive testing of carbon fibre reinforced plastic cfrp a thesis submitted to the university of manchester for the degree of doctor of philosophy in the faculty of engineering and physical science 2012 xin li school of electrical and electronic engineering. Eddycurrent coupling with slotted conductor disk ieee journals. Induction heating is the process of heating an electrically conducting object usually a metal by electromagnetic induction, through heat generated in the object by eddy currents. Coupled electromagnetic and thermal analysis of ferrite core. The coupling is improved through the magnetic flux. If eddy current losses can be entirely excluded, the energyefficient alternative materials peek and ceramics are available.
The magnetic field produced by circuit 1 will intersect the wire in circuit 2 and create current flow. Eddy current couplings are becoming popular devices for speed and torque control. Magnetic simulation done at fundamental frequency 100khz with harmonics up to 5mhz. Fast iterative solution of eddy current problems by a 3 d hybrid approach coupling the cell and the boundary element methods f.
Electromagnetic coupling is also known as transformer action. Magnetic couplings are capable of transmitting forces both linearly and rotationally. This is a delicate point, as eddycurrent problems, for the two cases a and b, have a unique solution already before a voltage or a current intensity is assigned. Each magnetic clutch shall consist of a stationary frame, a ring member driven at motor speed, and a variable speed member, bearings, outer bearing bracket and housing, heat exchanger if recommended by the manufacturer, motor. When current flows in an energized conductor, it produces an electromagnetic field at right angles to the conductor. The eddy current principle of torque transmission features no direct physical contact between the constant speed and output members. Eddy current dynamometer working principle, sales powerlink. Electronic pulsewidthmodulated pwm variable frequency drives vfd may be costeffective replacements for aging or highmaintenance eddy current drives that are used with variable torque loads, such as centrifugal fans or pumps.
Mutual inductance the basis for eddy current inspectionthe magnetic flux through a circuit can be related to the current in that circuit and the currents in other nearby circuits, assuming that there are no nearby permanent magnets. Presentation overview introduction to ansys electromagnetics. Custom magnetic couplings rapid prototyping and design. The purpose of this volume is to present the basic concepts of eddy currents, to explain how eddy currents are generated and distributed, to point out how the specimens magnetic and electrical effects relate to eddy currents, and to provide the basic electrical concepts related to eddy current. The attempt at a solution can anyone tell me two types of eddy current couplings. As a result, a magnetic breaking force is induced on the eddy currents which opposes the motion of the sheet. Like we said when the metal sheet passes between the poles of the magnet, circulating currents eddy currents are generated. Eddy current techniques for nondestructive testing of carbon. Eddy current level i ii course outline 40hrs ndt overview and certification requirements introduction to electromagnetic testing eddy currentflux leakage a. Electronic pulsewidthmodulated pwm variable frequency drives vfd may be cost effective replacements for aging or highmaintenance eddycurrent. In eddy current clutches and brakes the temperature coefficient of the copper is considered along with the temperature coefficient of the magnet.
Capacitors are usually classified, according to their dielectrics, as air capacitors, mica capacitors, paper capacitors, etc. Eddy current clutches and brakes heat up considerably due to the development of eddy currents with increasing rpm with temperature increase the value of the torque attainable decreases considerably. Eddy current level i ii course outline 40hrs ndt overview and certification requirements introduction to electromagnetic testing eddy current flux leakage a. Simulink model for pwmsupplied laminated magnetic cores. The torque measurement of eddy current dynamometer is according to the principle of same amount of applied torque and reaction torque with opposite direction. The problem has been treated by turck, duchateau and ciazynski 9, 10. There are many people whom have earned my gratitude throughout the course of this study, too many to name them all.
The documents may come from teaching and research institutions in france or abroad, or from public or private research centers. They are an adjustable speed drive and provide soft starting capability. Aluminium is commonly used as target for eddy current sensors and has a calculated penetration depth of 58. The drive unit consists of an ac induction motor driving the input member or fan pole assembly of the magnetic drive. And worked for five years in the re search department for hydrodynamic. The subject is presented under the following headings. Rajendran coupled mechanical and electromagnetic modeling of eddy current sensors nidhal jamia 1. Basic eddy current concepts, eddy current generation and distribution, coilspecimen coupling factors, specimens magnetic and electrical effects, and basic electrical concepts related to eddy current testing. An eddy current coupling 4 is proposed, with a first movable coupling. The main part of the work regards a pure analytical procedure. Coupled electromagnetic and analysis of ferrite core. Request pdf eddycurrent coupling with slotted conductor disk eddycurrent couplings are becoming popular devices for speed and torque control.
Furthermore, the eddy current coupling has a second coupling element 10. Eddy current methods have been utilized for more than 100 years as a means for detecting and characterizing. Bulletin 9000f1 1011 2 pulley eddy current separator maintenance and operating instructions check immediately when the eddy current separator is received for possible. Pdf electromagneticthermal model for improved axial. Eddy current testing ect technology works on the principle of magnetic coupling of a probe sensor coil close to a test specimen conductive material, ferromagnetic or nonferromagnetic, generating eddy currents inside the test specimen, and displaying signals on the instruments impedance plane.
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