Design and Optimization of Eddy Current Brakes

Eddy current versus traditional braking

Typical braking systems (hydraulic, pneumatic, mechanic) employed in most vehicles are designed to slow or halt the motion by converting kinematic energy into heat by friction. This type of brake suffers from several drawbacks including overheating, wheel damage, boiling or leaking of the brake fluid, low air pressure in pneumatic brake, and regular maintenance. On the other hand, eddy current, or electromagnetic, braking systems, which are based on Faraday’s law of induction, are contactless; these brakes have several advantages including wear-free, frictionless, less noise, low maintenance, protection from overheating, safety, and high efficiency in high-speed situations. They are used in many applications like traditional and maglev trains, automotive and heavy engines, roller coasters, gym and rowing machines, robotic and medical equipment, and wind turbines. However, eddy current brakes have some drawbacks such as low torque at low speed, and no ability to hold the moving load at a stationary position. 

Physics behind eddy current braking

A conductive object moves through a stationary magnetic field and develops induced currents called eddy currents, as described by Faraday's law of induction; by Lenz's law, the circulating eddy currents create their own magnetic field that opposes the source field. Hence the moving conductor experiences a magnetic force that opposes its motion and is proportional to its velocity. The kinetic energy of the moving object is dissipated as heat generated by the current flowing through the electrical resistance of the conductor. The source of the magnetic field can be permanent magnets, electromagnets, or a combination of them. 

Illustration of the eddy currents in a braking system

One-stop braking system design platform

An electromagnetic brake is a complex multi-physics problem; it includes electromagnetic, motion, thermal, and even structural aspects; FEM simulation is well-suited to overcome such aspects. EMWorks is a FEM-based complete solution that helps designers and engineers to design and improve their electromagnetic braking systems; it generates a magnetic field, eddy currents, electromagnetic losses, force and torque, speed, displacement, acceleration, and heat results in a one-stop integrated platform. 

Permanent magnet braking system

Electromagnet braking system

Hybrid braking system

Key design issues and challenges

EMWorks solution can help you solve most design challenges posed by an electromagnetic braking system, including: 

• Torque calculation of permanent magnet, electromagnet, and hybrid braking systems,
• Torque versus speed and air gap distance,
• Torque versus PMs, PMs arrangements and Halbach, and number of poles,
• Torque versus excitation current,
• Optimize the torque versus several inputs like air gap distance, moving parts geometry, i.e. disc thickness/diameter, configuration of the PMs,
• Deceleration torque and time,
• Dissipated power,
• Temperature evolution in a braking system.

Below are some results generated using the EMWorks solution.

Current distribution

Braking torque versus speed

Deceleration torque of a hybrid braking system vs time 

Speed variation of the hybrid braking system 

Temperature results of ventilated braking discs

Conclusion

Eddy's current braking systems represent a significant advancement in braking technology, offering a frictionless, maintenance-low solution for various applications. EMWorks facilitates the intricate design and optimization process of these systems, ensuring they meet the high standards of safety, efficiency, and performance required in today's fast-paced world.