Keywords: Magnetic brakes; eddy-current magnetic brakes; optimum control. friction, an eddy-current braking system transforms the kinetic energy of the. Get More Information about Eddy Current Brakes PDF Download by visiting this link. Eddy current is the swirling current produced in a. An eddy current braking experiment was conducted to study the behaviour of three different materials to be used as brake disc which are aluminium, copper and zink. A few graph been presented in this paper to show the best material to be used as the brake disc for electromagnetic.
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Eddy Current Brakes - Free download as Word Doc .doc), PDF File .pdf), Text File .txt) or read online for free. The document reports the progress of Team 16's Eddy Current Brake design. experimentation resulting in optimized eddy current brake/motor configuration. International Research Journal of Engineering and Technology (IRJET) e-ISSN: Volume: 03 Issue: 04 | Apr pawnfacumapbma.gq p-ISSN:
This section describes several kinds of measurements that can be carried out with the proposed experimental setup. In all cases typical results are included. Braking time of the disc: First of all, the time necessary for the disc to completely stop from a fixed initial angular speed when the motor is turned off can be measured as a function of the excitation intensity. We must keep in mind that the larger the excitation intensity is selected, the larger the voltage applied to the motor must be to achieve that initial speed.
Figure 3 shows how larger excitation intensities make the braking time shorter as a result of more powerful eddy currents. Error bars have been set to 0. However, the results plotted in figure 3 are not suitable for verifying this fact, due to the lack of a known model for the internal braking torque acting on the motor.
Therefore, the result of this first experiment cannot be numerically tested. Figure 3. Braking time for the copper disc versus excitation intensity. The initial speed of the disc was set to rpm.
Eddy current losses versus angular velocity: Then the voltage supplied by the power source of the motor must be varied in order to select various angular speeds. Then the power dissipated only by eddy currents is simply: Standard error analysis techniques have been used to calculate error bars, assuming uncertainties of 0. Eddy current losses versus excitation intensity: Equation 1 states that Pe is proportional to the square of the excitation intensity in the coil.
The excitation intensity was fixed to 3. An example to test the proportionality between Pe in the copper disc and I 2 ex.
Eddy Current Brakes
The angular speed was fixed to rpm. Above figure shows a set of typical results. It appears that the proportionality between Pe and I 2 ex does not hold, especially at low intensities. Nevertheless, we must recall that the core of the electromagnet is made of iron, i.
In fact, it would be interesting to use a coil alone as a truly linear source of magnetic field. Unfortunately, the absence of a ferromagnetic core results in low magnetic fields and therefore Pe becomes too low to be measured with conventional ammeters and voltmeters.
To carry out such a test, both rotation speed and excitation intensity must be fixed, and the power consumed by the motor with each of the discs attached to it must be calculated. Pe is estimated by subtracting from this power the power consumption of the motor alone turning at the same angular speed better, a non-conducting disc equal in size to the conducting ones should have been used, but the difference is negligible.
Table 1 shows the results. The angular speed and the excitation intensity were fixed to rpm and 3. Tabulated resistivities were extracted from a general reference , and exact coincidence with those of the sample discs cannot be guaranteed, especially in the case of alloys.
As we can see, results for aluminium, copper and brass show a reasonable agreement with equation 1. The case of steel, however, is clearly anomalous because of its ferromagnetic behaviour. The time variation of the magnetic field applied on every point of the disc results in hysteresis loops creating an additional braking effect superimposed to eddy current torque see, for example, .
How Eddy Current Braking Technology Is Freeing Us from Friction
This is probably the main reason for the high total losses observed in steel. From the above it may be deduced that: As we have seen, our experimental setup allows students to investigate one of the most outstanding aspects of eddy currents, namely their dissipated power. Simple tests to measure Pe and to study its functional dependence on the velocity, the sources of the magnetic field and the sample resistivities have been carried out.
The results show a reasonable but not indisputable agreement with theoretical predictions. Nevertheless the author believes that the experiments deal with concepts, instruments and measurement techniques with high didactic value for the students, regardless of whether the agreement between theory and experiments is good or poor. Flag for inappropriate content. Related titles. Jump to Page.
Search inside document. Liquid Cooled Eddy-Current Brakes: Stopwatch A list of all necessary elements follows: The influence of disc resistivity: Prashant Pandey. Awais Malik. Mridul Bora.
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Jigar Patel. Allelectricalinterviewquestions4u Blogspot in p Blog Page John Johnson. Hari Reddy. Some vehicles use a combination of braking mechanisms, such as drag racing cars with both wheel brakes and a parachute, or airplanes with both wheel brakes and drag flaps raised into the air during landing. In practice, fast vehicles usually have significant air drag, and energy lost to air drag rises quickly with speed. Friction brakes on automobiles store braking heat in the drum brake or disc brake while braking then conduct it to the air gradually.
When traveling downhill some vehicles can use their engines to brake. When the brake pedal is pushed the caliper containing piston pushes the pad towards the brake disc which slows the wheel down. On the brake drum it is similar as the cylinder pushes the brake shoes towards the drum which also slows the wheel down. When stepping on the brakes, the driver commands a stopping force several times as powerful as the force that spots the car in motion and dissipates the associated kinetic energy as heat.
Brakes must be able to arrest the speed of a vehicle in short periods of time regardless how fast the speed is.
As a result, the brakes are required to have the ability to generating high torque and absorbing energy at extremely high rates for short periods of time. Brakes have to have the mechanism to keep the heat absorption capability for prolonged periods of time.
Brake fluid, specially designed to work in extreme temperature conditions, fills the system. Two major kinds of friction brakes are disc brakes and drum brakes.
Eddy Current Brakes
Drum brakes consist of a heavy flat-topped cylinder, which is sandwiched between the wheel rim and the wheel hub. The inside surface of the drum is acted upon by the linings of the brake shoes. When the brakes are applied, the brake shoes are forced into contact with the inside surface of the brake drum to slow the rotation of the wheels.Thomas Forrister March 6, Nowadays, the need for travel is growing — and with it, transportation alternatives that are greener; less noisy; and, of course, faster.
The controller provides the DC excitation for the brake coil. Ajoy Rs. This is the foundation of the electromagnetic braking systems used by heavy vehicles such as trains, buses or lorries.
If the conductor is a disc, there will be circulatory currents i. This causes skidding and wear and tear of the vehicle. Stator consists of pole core, pole shoe, and field winding.