How dynamatic technology works adjustable speed drive system. Evaluation and improvement of eddy current position. The eddy current drive is installed between the motor and the driven equipment. This unique braking system takes the simple function of magnetic and nonmagnetic forces and turns it into a high tech masterpiece. Welcome to the premier industrial source for clutches. Output speed is adjusted by controlling the excitation of the eddy current clutch by means of a closed loop technique with speed feed back. York specializes in services such as eddy current clutch repair. Welcome to contact us for more information about our dynamometer retarder list and prices. The truth about eddy current drive efficiency empowering.
This is the basis of eddy current testing, by monitoring the voltage across the coil in such an arrangement we can detect changes in the material of interest. This is a simple theory of magnetic braking, which assumes that the magnetic field generated by the induced current is negligible in comparison with the applied magnetic filed. This reduced saving was due to the removal of hysteresis and eddy current losses from the stator. Long stator end effects could be modeled by simply modeling the entire length of the plate in the present style of analysis, adding a few extra wavelengths of stator on either side of the plate. The potential of eddy current clutches is assessed from a representative case study consisting of a. Automotive transmission efficiency measurement using a chassis dynamometer 557 an increased scatter of measured points was observed at low speed, below 60 kmh figures 3 and 4. Find types of eddy current clutch motor related suppliers, manufacturers, products and specifications on globalspec a trusted source of types. Eddy current drive is an electromechanical device, which operates on eddy current principle. This tach generator rotor fits some of the ed 40 and ed 41 frames from the us electric and wer eddy current clutches. The annual energy consumption of the existing system or eddycurrent baseline is calculated in table 2. As previously mentioned, the chassis dynamometer measures engine power only above 50 kmh vehicle speed during acceleration trials. As a result of the changes implemented, gt, a subsidiary of the delawarebased chart industries, discovered that energy efficiency and improved productivity often go handinhand. The physical working principle is the same for both. Eddy current transmission drive kingstone model works.
The eddy current drive also called a magneticallycoupled adjustable speed drive, which consists of an eddy current clutch and associated controls, is favored for heavyduty applications with high starting torque and severe shock loads. The armature or rotor is constructed so that when the winding is excited with direct current, magnetic pole pieces are formed. But we know that in dc machine ac current flows in the armature winding and a constant airgap flux is produced because of field wind but due to armature rea. Design of an eddy current torque bypass clutch for seamless. In mountain areas where continuous braking force is needed, for a long time, the eddy current braking is very much useful for working without overheating.
Eddy current clutches give torque as a function of rpm. The speed is externally controlled and the operating efficiency of eddy current drive is around 80%. Computer based eddy current test instrument manufactured by highline automation. An eddycurrent drive on a standard efficiency motordriven 50hp boiler forced draft fan has reached the end of its useful operating life.
Selfexcited eddy current brake to be studied in this paper is the eddy current brake according to the regenerative braking. Reduction of eddy current losses in inductive transmission. Eddy current clutch working, application, advantages and. This is a clutch coil for some of the ed 40 and 41 frame eddy current drives.
The eddy current clutch is usually tended to the small speed ratio no more than1030% speed reduction due to consideration of efficiency and cooling. Design optimization of an axialfield eddycurrent magnetic coupling. Us electric wer eddy current parts electric maintenance. A wide variety of eddy current brake retarder for dynamometer options are available to you, such as usage, power. A wide variety of manufacturers, distributors and service companies are featured in our extensive vertical directory to allow ease sourcing and research for drives. The supplier of this item is approved as a verified supplier.
We provide repair services from 56 frame through 49 to 63. The instrument is a dual channel dual frequency instrument. The eddycurrent drive or clutch is a slip device consisting of two rotating elements that are coupled by a magnetic field. This improves the efficiency of the motor significantly. Thus, eddy currents occur in the stator and rotor cores of electric motors and generators, in transformers, metallic recording heads used in magnetic recording, and the like. One advantage of eddy current clutch is that the smooth adjustment of both output torque and hence the speed control. Evaluation and improvement of eddy current position sensors. Dynamatic adjustable speed drives and digital controls are designed to. Figure 2 shows a top view of the radial eddy current position sensor configuration. In eddy current drive, speed is varied by varying the field of eddy current coupling.
As a result, a magnetic breaking force is induced on the eddy currents which opposes the motion of the sheet. The use of power from the vehicle battery has adverse effects on vehicle fuel economy and lifetime of the battery. The controller sends voltage to the clutch coil to operate and regulate the speed of the eddy current clutch. A set of simple experiments is proposed to measure eddy current losses and to relate them to various relevant parameters. Improvements in eddy current suppression are necessary to meet the demand for increasing miniaturization of inductively driven transmission systems in industrial and biomedical applications. Eddy current linear encoders eddyncdt eddy current sensors dt3005s2ac1 supplier. Sharon lin stuyvesant high school enhancing the efficiency of a torque converter clutch lockup system using a computational simulation 2. Eddy current, as well as a variety of related products and services.
As the eddy current drive efficiency drops rapidly at loads below 70%, energy savings are extremely sensitive to the load profile and duty. Nine eddy current position sensors are used in the development system. The eddy ncdt 3005 is a compact, powerful eddy current measurement system for fast, high precision displacement and position measurements. Abstract the torque converter is a fluid coupling that typically replaces the rotating clutch system in automatic transmission, allowing for the engagement and disengagement of power transmission. Eddy current drive is a combination of a constant speed ac induction motor, coupled to an eddy current clutch. Efficiency, life cycle costs and the eddy current drive 215kb pdf. In a circular, disk or rotary eddy current brake, the conductor is a flat disk rotor that turns between the poles of the magnet.
An eddy current drive sometimes called a dynamatic drive, after one of the most common brand names consists of a fixed speed motor generally an induction motor and an eddy current clutch. Eddy current brake retarder for dynamometer testing machine kas series air cooled eddy current dynamometer retarder is designed based on the domestic automobile testing equipment. The prime mover is an ac induction motor, the work horse of industry today. The annual energy consumption of the existing system or eddy current baseline is calculated in table 2. As the eddycurrent drive efficiency drops rapidly at loads below 70%, energy savings are extremely sensitive to the load profile and duty.
Figure 1 the control supplies dc voltage to the drive field coils and automatically varies drive excitation to maintain desired speed, torque, tension, position, or horsepower, as determined by the feedback signal. Dec 10, 2015 eddy current clutches eddy current clutches are so named because they in duce eddy currents into a metal cylinder or drum. The function of an eddy current clutch is to transmit a controlled torque from the induction motor,prime mover to the load driven machine. Note that cracks must interrupt the surface eddy current flow to be detected. Oct 15, 20 eddy current breaking presented by sachin prakash u10ee084 electrical department slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Eddy current clutch as well as fan coupling with eddy current clutch. This showcase demonstration project reduced total annual. An eddy current drive, also known generically as a magnetic drive, eddy current clutch or magnetic clutch, is an electromechanical variable speed drive that uses a constant speed motor as the input. An eddy current drive controls speed by regulating a dc excitation coil on a magnetic rotor, rotating concentrically with a steel drum, driven by the motor at full speed as illustrated in figure 1. Electric wheelchairs have a considerable impact on improving the quality of life for the millions of disabled persons around the world. An eddy current coupling 4 is proposed, with a first movable coupling element. When switching to a vfd for a constant torque load, the motor and the drive may require being oversized by a factor of 150% to 200 %. One part of the clutch contains slip rings and a winding figure 428a.
The automatic adjustment of the excitation current occurs at a low power level. The basic function of a transmission, together with the differential, is to reduce the relatively high engine output speeds to the vehicles slower wheel speeds and to increase the torque applied to the wheels. Custom magnetic couplings rapid prototyping and design. The eddy current clutch prototype doesnt meet the torque requirement of 193 nm on the slip speed range see table 3, because of clutch geometric constraints imposed by the retro fit. The medium of torque transmission is a controlled magnetic field, generated by a stationary. If you continue browsing the site, you agree to the use of cookies on this website. 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. Pdf design and experimental demonstration of a seamless. Enhancing the efficiency of a torque converter clutch tcc. A basic analysis of a long stator eddy current brake has been presented in this notebook.
Eddy current drives, also known generically as magnetic drives, eddy current clutches or. It is a rugged industrial drive which has been proven in the past 60 years by thousands of units in nearly every industry. The kinetics svr1ec speedregulated, eddy current clutch field exciter is a scr regulated rectifier system specifically designed for the application of supplying regulated variable dc power, via a closed feedback loop system, to the field coil of an eddy current clutch adjustable speed drive. The setup operates like an eddy current brake, a device commonly used in heavy vehicles to dissipate kinetic energy by generating eddy currents. In eddy current clutches and brakes the temperature coefficient of the copper is considered along with the temperature coefficient of the magnet. Eddy current brakes are best substitutes for ordinary brakes, which are being used nowadays in road vehicles even in trains, because of their jerkfree operation. Design and fabrication of an eddy current brake dynamometer. Variable frequency drivesenergy efficiency reference guide. Is it costeffective to replace old eddycurrent drives. The prototype performed a seamless shift on a test bench demonstrating the viability of using an eddy current clutch for torque bypass clutches in amts. Blog 5 applications of eddy current brakes head rush tech.
The range of dynodrive variable speed drives covers all standard ratings, from 0. The companies featured in the following listing offer a comprehensive range of clutches. Eddy current analysis and optimization for superconducting. This paper examines four options for adjustable speed drive systems. The eddycurrent drive also called a magneticallycoupled adjustable speed drive, which consists of an eddycurrent clutch and associated controls, is favored for heavyduty applications with high starting torque and severe shock loads. The operating principle of a double clutch is complex, but can be explained in a relatively simple manner. One clutch is used for the uneven gears one, three, five, and seven, while the second controls the disengaging and.
The primary elements of powermag eddy current variable speed drive are an ac motor, an eddy current clutch, a tacho generator and a seperate small solidstate electronic controller. Eddy current drive characteristics the eddy current drive is the simplest of all electrical adjustable speed drives. Request pdf design of an eddy current torque bypass clutch for seamless. The product dynamometer manufacturer from thrissur. Magnetic couplings are capable of transmitting forces both linearly and rotationally. The highline automation ec14 has a frequency range of 40hz to2 mhz the instrument will meet or exceed the requirements of appendix a. Eddycurrent clutch article about eddycurrent clutch by. As you might think, dc current do not produce eddy current and hence no eddy current loss. Powermag eddy current variable speed drives are economical and widely used for various industrial applications. Together with the tach generator stator, it puts out a signal proportional to the output rpm so the controller can regulate the speed of the clutch.
Careful design consideration must be given to providing adequate cooling of both field coil and metallic drum. Radial sensing is achieved using two sets of four sensors top and bottom, and axial sensing is done using a single sensor located at the top of the unit. The slip between the input drum and the output rotor produces a slip loss. The problem that occured which drew my attention to the coupling, was an intermittant speed variation, no change in controller output, and no shorted leads on the eddy coupling, just random speed changes, sometimes a slight rise, most often a slow down, no faults present, then it would just pick and run again. In a linear eddy current brake, the conductive piece is a straight rail or track that the magnet moves along. In the case of existing electric retarder, this used the battery of the vehicle as a power source. Eddy currents are induced in any conducting medium in which the magnetic field varies with time.
About 10% of these are testing equipment, 1% are weighing scales. Consequently, in addition to selecting the class of coupling required synchronous, eddy current, or hysteresis, the coupling type also needs to be specified. True system efficiency dynamatic technology eddy current. An eddy current clutch would be highly controllable, simple to manufacture, lowcost, robust, and do not wear compared to friction clutches. 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. The speed and torque can regulate by adjusting the dc. The paper also demonstrates during a competition in which the driver was.
Eddy current clutches eddy current clutches are so named because they in duce eddy currents into a metal cylinder or drum. The double clutch consists of two clutches arranged on two drive shafts. Characteristic analysis of the selfexcited eddy current. The high magnetic permeability and the simultaneously low electrical conductivity of ferrite materials make them ideal candidates for shielding metallic surfaces. The clutch contains a fixed speed rotor and an adjustable speed rotor separated by a small air gap. Our electromagnetic eddy current engineering is simply better by design. The value of a clutch mechanism in electric vehicle s. Design and fabrication of an eddy current brake dynamometer for efficiency determination of electric wheelchair motors.