Braking systems?

Question

I have to compare regenerative and electromagnetic braking systems, but i really can't think of anything. The only thing i have so far is that they both use induction.

I was also thinking that the electromagnetic braking would be more efficient, because there are no parts which can wear out and need replacing, and if permanent magnets are used they need no power input, whereas the regenerative braking systems, regardless of how well it charges when braking still looses energy, and has parts which can wear out, like brushes, but i'm not sure if this is true, it's just an idea i had.

So is that idea right, and does anyone have any other suggestions?

Answer 1

As i recall electromagnetic braking requires applying a current to induce a magnetic feild to oppose wheel rotation. wheras regenerative braking allows the rotating wheel to induce a current used to charge the energy storage system. So there is a philosophical difference in the direction of energy application.
True the back emf in regenerative braking is similar to the applied emf of em braking, but I'm speaking more about the energy entering or leaving the batteries

Answer 2

I like the Regen brake.
Anyway, I think both brake systems all need to work in conjunction with a friction brake because they always have some limitations on the braking performance.

Basically, regen brake is a device which can slow the vehicle speed using an electrical machine (in generator mode), but electromagnetic braking systems create the eddy current in the disc and these currents generate an opposing magnetic field, which can resist the rotation of the disc, providing braking force and dissipating the kinetic energy at the same time. If you want to say, they both use indunction, I'd say they use the induction in a different way.

For the vehicle brake designers, the regen brake would (should) be the primary brake, the eddy-current brake is the secondary brake and the friction brake is the teritary brake, because they prefer the energy recovery to the energy dissipation. And there are some drawbacks for the electromagnetic braking systems. For example, the electromagnetic braking force is very low at low vehicle speed and since the eddy-current brake generates a huge heat energy during braking, this high temperature could result in the deformation of the disc.

And you're right. The regen brake cannot recover 100% braking energy, but brake system components will not easily wear out. I think the battery in hybrid cars will be replaced first.

And you may say, their torque-speed curves are similar, so the regen also provides low braking force. I'd say, regen is better, because if the electric motor has higher power rating and the energy storage device is not full, the regen brake can offer bigger braking torque compared with the eddy-current brake. However, if the vehicle is in downhill driving, the eddy current brake will be the primary brake.

Answer 3

A better comparison is that electromagnetic braking can be one type of regenerative braking. there are hydraulic accumulative systems that are currently being tested in trucks. The hydraulic systems use a hydraulic motor on the wheel, and when braking it pumps fluid into the accumulator. during acceleration the fluid is released back through the motor and helps to drive the wheel.

Electric systems use the same principle, except batteries are the accumulator. With the new brushless motors the wear parts (rushes) are eliminated. however, the magnets can be expensive. Look at total life cycle cost when determining the best valued system!

Answer 4

Some hybrid cars do this but they use the energy to charge the batteries. This might be a good place to look for information.