A wall mounted solidstate controller converts a relatively small amount of ac power to dc to energize the field coil of the eddy current clutch. Modeling and optimal design of an eddy current coupling. The eddy current coupling forms a basic variable speed drive, which is widely applied to regulate the flows from large pumps and fans for a remarkable energysaving effect. In this study the possibility of using an eddy current coupling as the slip permanent magnet generator is investigated.
This paper presents different analytical and numerical approaches devoted to the analysis and design of axial eddy current couplers. Eddycurrent drives can produce more torque at low speed than an induction motor and vfd. The aim of the present paper is to model the dynamic behavior of eddy current dampers and couplers and, by extension, of resistively shunted synchronous motors with permanent magnets. 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. Case studies for two, three, and fourlayer rotors have clearly established their superiority over the conventional couplings, from the point of torque transmission, losses and. This linking generates eddy currents in the driving rotor. The eddy current loss calculation usually receives less attention than the torque analysis. The pump is attached to a 15hp motor through an eddy current coupling. For permanent magnet eddy current couplings, the magnetic field is. Dynamic characteristics of eddy current dampers and. Huang, a general analytical model of permanent magnet eddy current couplings, ieee trans. Pdf an improved practical twodimensional model for the analytical calculation of. Custom magnetic couplings rapid prototyping and design.
A novel brushless hybrid excited adjustable speed eddy current coupling is proposed for saving energy in the drive systems of pumps and fans. Reduction of the field current weakens the magnetic coupling between the stator and rotor and can lead to a loss of. Eddy current dampers are promising devices for the passive, semiactive and regenerative control of vibrations. The eddy currents are quite denser at the surface as compared to the deep inside, an effect referred to as. We offer both aircooled and watercooled designs built with our reliable and durable eddy current technology for long service life. 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. Pdf a general analytical model of permanent magnet eddy. Eddy current loss calculation and thermal analysis of axial. The pdc2000 constantly monitors the eddy current coupling andevaluates the performance in an attempt to ensure the quality of the drive and apprising the machine operator of the condition that would lead to improper operation and subsequence failures. Since the eddy current coupling is a slip speed power transmitting device wherein the output member rotates at a speed less than that of the input member in order to obtain the coupling action, the horsepower difference between the input and output members is converted into thermal energy.
May 23, 2018 it is an abrasionfree method for braking of vehicles including trains. The topology and operation principle of the coupling are presented. Variable frequency drives and dc drives operate by electronically altering the input power to control the speed of the motor. Gear coupling selection procedure table 1 torque and horsepower ratings standard selection method the standard selection method can be used for most motor, turbine, or engine driven applications. Determining eddy current coupling losses electric motors. Nonlinear modeling of transmission performance for permanent. International union of theoretical and applied mechanics. With the development of permanent magnet pm material, a high torque density adjustable speed pm eddy current coupling aspmecc oregon state university, corvallis, or, usa has been developed and applied in the field. An improved performance prediction model of permanent magnet. The prefault loading is a determining factor in the final value of slip.
In this study the possibility of using an eddy current coupling as the slip permanent. The attempt at a solution can anyone tell me two types of eddy current couplings. Coil is glass taped and epoxy moulded to prevent ingress of moisture or dust. Stromag is the leader in industrial brakes, couplings, clutches and controllers. Design optimization of an axialfield eddycurrent magnetic. Voltage and current intensity when one wants to couple the eddycurrent problem with a circuit problem, one. An axialflux eddycurrent magnetic coupling consists of two discs facing each other. In this paper the possibility of using an eddycurrent slip coupling to remove cogging torque and torque ripple in a slipsynchronous permanent magnet wind. An axialflux eddycurrent magnetic coupling consists of two discs facing each. Shop the industrys best selection of set screw slip couplings at garvin industries. Modelling and design of an eddy current coupling for slip synchronous permanent magnet wind generators december 2012 iv acknowledgements.
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. 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. The flow of eddy currents in the test material is not uniform at different depths. The design procedure is based on a torque formula derived from a 3d analytical model and a population algorithm method. They are an adjustable speed drive and provide soft starting capability. Given the existence of the slip, the eddy current coupling the maximum efficiency is. Eddy current clutch working, application, advantages and. Electrical machines i viva short questions and answers pdf. Enjoy easy ordering, quick delivery, and great prices, plus free shipping on select purchases. The pdc2000 constantly monitors the eddy current coupling andevaluates the performance in an. Given the existence of the slip, the eddy current coupling the maximum efficiency is lower than.
A threedimensional magnetic field analytical model of axialflux permanent magnet couplers is presented to calculate the eddy current loss, and the prediction of the copper plate temperature under. Coupling finite elements and boundary elements in eddycurrent computations. When the changing flux links with the core itself, it induces emf in the core which in turns sets up the circulating current called eddy current. This invention relates to eddy current apparatus, and with regard to certain more specific features, to infinitely variable torque transmissions of the eddy current slip clutch type. 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. All scanners work with the nortec 2000s series, nortec workstation and powerstation. Mar 26, 2019 the eddy current distribution of the copper rotor is shown in fig. Electronic pulsewidthmodulated pwm variable frequency drives vfd may be costeffective replacements for aging or highmaintenance eddy current drives that are used with. Since the output or driven member of an eddy current coupling rotatesat a speed which is less thanthat of the input or driving member, the difference in such speeds is converted into thermal energy, which is heat. Eddy current, coupling systems, finite element, electromagnetism 1. Because of the tendency of eddy currents to oppose, eddy currents cause energy to be lost.
An eddy current brake having an electromagnetic pole and the rotor is positioned in close proximity. Available in a complete range of carbon steels, stainless steels, alloy steels and non ferrous metals certified to astm, asme, and military standards. Background of the invention this invention relates to an eddy current coupling which is a slip speed powertransmitting device. Case studies for two, three, and fourlayer rotors have clearly established their superiority over the conventional couplings, from the point of. Establishing the analytical model for accurately predicting the transmitted torque of the permanent magnet eddy current coupler pmec with double conductor rotors is very important to study the nonlinear transmission performance of the pmec. Eddy current loss calculation and thermal analysis of. Eddy current is the swirling current produced in a conductor, which is subjected to a change in magnetic field. A general analytical model of permanent magnet eddy current couplings. Consequently, the coupling currents and the corresponding coupling current losses, can be much larger than the eddy current losses. Nonlinear modeling of transmission performance for. Design and steadystate performance of a novel winding type. Rao nondestructive evaluation division metallurgy and materials group. Modelling and design of an eddy current coupling for slipsynchronous permanent magnet wind generators december 2012 iv acknowledgements.
Based on the real flux paths, the fluxes excited by permanent magnet pm and field current are analyzed separately. 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. However, the analytical modelling of the eddy current coupling is complex. An eddy current clutch relies on electromagnetic forces to create a coupling torque.
This motion determines an electric field in the conductor that induces eddy currents. Jul 30, 1974 an eddy current coupling comprising coaxial input and output shafts, a pole member connected to one of the shafts and having a series of poles provided with one or more field windings, alternate poles exhibiting the same polarity on excitation of the field winding or windings, and a loss member which comprises a support connected to the other. Eddy current drives, also known generically as magnetic drives, eddy current clutches or magnetic clutches are driven at constant speed by an ac motor and utilize a simple electromagnetic device to control torque and speed to the driven load. Download citation modeling and optimal design of an eddy current coupling for slip synchronous permanent magnet wind generators in this paper, the possibility of using an eddy current slip. Introduction the working principle of eddy current couplers relies on the interaction between a conductor in motion with respect to a magnetic field. Moreover, due to the induction of eddy current in the conductive rotor, the slip power, that is the power difference between input and output terminals, is dissipated as heat and can not be recovered. An eddy current drive system consists of ac motor and eddy current coupling, a control and operators control station. Design optimization of an axialfield eddycurrent magnetic coupling. When starting eddy current clutch operates at 100% slip allow the driver motor to accelerate. Magnetic couplings are capable of transmitting forces both linearly and rotationally.
Watercooled couplings wcs couplings eddy current coupling. The drive unit consists of an ac induction motor driving the input member or fan pole assembly of the magnetic drive. There is a serious nonlinear relationship between slip and torsion of permanent magnet eddy current magnetic couplings pmec and how to establish mathematical model is very important to study characteristics, optimize parameters and improve control accuracy. Since the eddycurrent coupling is a slip speed power transmitting device wherein the output member rotates at a speed less than that of the input member in order to obtain the coupling action, the horsepower difference between the input and output members is converted into thermal energy.
The eddy current coupling has the attractive advantage of completely removing cogging and load torque ripple, which are known problems in the sspmg. Coupling finite elements and boundary elements in eddy. This will significantly decrease the couplings efficiency under largeslip conditions. Design of an eddy current coupling for slip synchronous permanent magnet wind generators. The transmitted torque of such a device is due to the interaction of magnets field and induced currents in the conducting plate which depend on the slip speed between the two discs.
The composite rotor is constructed with a number of layers of materials with different permeabilities and conductivities. A simple method for performance prediction of permanent magnet eddy current couplings using a new magnetic equivalent circuit model. The single flexing coupling is for use in the case where shafts are supported by three bearings. Downloaded from sae international by ithakajstor, sunday, june 11, 2017. Easy computer upload and download of speed parameters all parameter programmable from removable keypad. And these current in return produces a loss called eddy current loss or i 2 r loss, where i is the value of the current and r is the resistance of the eddy current path. Design of an eddycurrent coupling for slipsynchronous permanent magnet wind generators. I can find out how much power the motor is using at any given moment as well as the shaft speed on the pump side of the ecc. Baylor elmagco eddy current brake, model 7838 installation, operation and maintenance manual 1.
Manual transmissions of electric and hybrid vehicles. This invention relates to eddycurrent apparatus, and with regard to certain more specific features, to infinitely variable torque transmissions of the eddycurrent slip clutch type. The main part of the work regards a pure analytical procedure. There is no mechanical linkage between input and output members of the drive. The dynamic eddy current is considered as an inductance limited eddy current. The slip power recovery efficiency for the 2d fea is 66. Eddycurrent, coupling systems, finite element, electromagnetism 1. Engineered for the demands of heavy industry, companies in sectors from transportation, energy, oil drilling, steel, shipping and more depend on stromag equipment and replacement parts to keep operations running and safe. Modelling and design of an eddy current coupling for slip. A method of computation of transient magnetic fields in three dimensions is described, which combines finite elements of the mixed variety and boundary integral methods.
An improved performance prediction model of permanent. Design and steadystate performance of a novel winding. Slip coupling definition is a form of coupling adapted for use on slip carriages. These ruggedly constructed clutches require no brushes, slip rings or commutators. An analysis of an eddy current coupling uith a composite rotor is prssented. Coupling currents and hysteresis losses in mgb2 superconductors. A magnetic circuit equivalent mec model is established to. Timeharmonic modeling of squirrelcage induction motors. Baylor elmagco eddy current brake, model 7838 installation. Among the several objects of the invention may be noted the provision of an infinitely variable eddy current. In eddy current clutches and brakes the temperature coefficient of the copper is considered along with the temperature coefficient of the magnet. Consequently, in addition to selecting the class of coupling required synchronous, eddy current, or hysteresis, the coupling type also needs to be specified. Slip coupling definition of slip coupling by merriamwebster. By controlling this dc power to the field coil, the output speed can be regulated.
Abstractthis paper presents a design optimization of an axialflux eddycurrent magnetic coupling. Emphasis is on the coupling, and on how the special nature of the finite elements is crucial in this respect. It is suggested that you save the packing slip as proof of delivery. From its working principle, eddycurrent coupling presents joule losses, which are directly related to the slip speed. Eddy current brakes adjustable speed drives dynamatic. Slip induces damaging currents into the amortisseur damper windings of the rotor and the body of the rotor. Pdf eddy current loss calculation and thermal analysis of axial. I would like to thank my fellow students and the technical staff of the electrical machines laboratory. The eddy current coupling usually consists of three basic members.
Twodimensional model of a pm eddy current coupling. Electronic pulsewidthmodulated pwm variable frequency drives vfd may be costeffective replacements for aging or highmaintenance eddycurrent drives that are used with. In this paper, based on magnetic equivalent circuit mec approaches, considering the effects of permanent magnet pm end leakage, side leakage, and. The main objective of this paper is to determine the best design in terms of magnets volume in order to transmit a torque between two movers, while ensuring a low slip speed. Is it costeffective to replace old eddy current drives. Among the several objects of the invention may be noted the provision of an infinitely variable eddycurrent. Capability curvebased generator protection minimizes. From its working principle, eddy current coupling presents joule losses, which are directly related to the slip speed. The following five eddy current rotating scanners are available. Introduction the working principle of eddycurrent couplers relies on the interaction between a conductor in motion with respect to a magnetic field. To connect the servomotor used in nc machine tools with the ball screw, an exceptional usage of the coupling as shown in the. Therefore, the research methods of electromagnetic components such as motor and eddy current brake are used for reference.
There are many people whom have earned my gratitude throughout the course of this study, too many to name them all. This paper presents different analytical and numerical approaches devoted to the analysis and design of axial eddycurrent couplers. I am trying to determine how much power a pump is using. The eddy current loss is minimized by laminating the core, the laminations being used from each other by light coat of coreplate vanish or by oxide layer on the surface. The coupling currents can be reduced by reducing the area of the loop reducing the enclosed magnetic. The coupling shown in the diagram on the right above is suitable for use in cases subject to great radial loads.
Gear coupling selection procedure table 1 torque and horsepower ratings. Eddy current brakes must have a slip between the rotor and the stator to generate torque. Eddy current adjustable speed drives design features the following figuresofmerit may be compared for an objective study of eddy current drives of different brands. Nov 20, 2014 baylor elmagco eddy current brake, model 7838 installation, operation and maintenance manual 1. The variable speed output shaft is rotated by the constant speed a. Kamper, design of an eddycurrent coupling for slipsynchronous permanent.
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