Ultra-High-Speed Magnetic Bearings

No friction, no limits: Magnetic bearings do not only increase lifetime but also enable vacuum operation with highest rotational speeds. With our technology you can reach 500,000 rpm and more.

Every engineer knows the equation that high rotational speeds come along with high abrasion and reduced lifetime of the ball bearings.

As a high speed specialist Celeroton is particularly faced with this challenge. This is why we offer a technologically leading alternative for unlimited lifetime despite highest rotation speeds - our ultra-high-speed magnetic bearings. We have integrated the technology in the new motor CM-AMB-400.

Advantages

  • Lifetime
    Magnetic bearings increase lifetime to (theoretically) unlimited runtime, irrespective of the operating speed and the number of start/stop cycles.

  • Operation in vacuum
    Bearing forces are only generated electromagnetically and neither a lubricant nor an atmosphere is needed. Therefore, magnetic bearing technology is the only technology which enables vacuum operation with high rotational speeds.

  • Active control of rotor dynamics and vibration
    Active control of the magnetic bearing allows for control of the rotordynamics at critical speeds  as well as to damp vibrations.

Disadvantages

  • Additional volume

  • Low bearing force

  • Standard magnetic bearings: Limited rotational speed due to increasing reactive power and losses

Operating principle

Most magnetic bearing concepts are based on reluctance forces. A magnetic flux in the air gap between stator and rotor generates these forces whereas the flux is regulated by stator currents.

 Operating Principle

Functional principle of an active magnetic bearing


In this magnetic bearing type, the rotational speed is limited due to increasing eddy current losses in the rotor and stator iron, a limited actuator bandwidth and a high reactive power demand. Therefore, magnetic bearings have only been successful up to rotational speeds of about 120,000 rpm.

To overcome these rotational speed limits, Celeroton has researched a new magnetic bearing concept. The new bearing enables rotational speeds of 500,000 rpm and more, which represents the world record for a magnetically levitated drive system.

The bearing is based on Lorentz forces instead of reluctance forces. A winding, which lies in the air gap between the rotor magnets and the stator iron, generates these forces – electric current in the winding regulates them. The magnetic field of the permanent magnet can also be used for the generation of the torque, which enables a short design of the motor as so called bearingless motor.

Celeroton-Magnetic-Bearing 

Generation of forces and torque of a Celeroton magnetic bearing motor

Application Examples

  • Optical systems with high rotational speeds such as beam choppers and rotating mirrors
    These applications are operated in vacuum or helium atmosphere to minimize air friction losses, and to protect the optic from pollution. The disadvantages of magnetic bearings regarding space requirements and complexity are not critical, as the whole system is much bigger and more complex than the bearing itself.
  • Reaction wheels for satellites
    Reaction wheels are used in satellites to control and stabilize the attitude in the space. They are moved to the desired position by rotational speed regulation. As satellites depend on light components, reaction wheels are often designed with the aim to reduce weight by increasing the rotational speed. Furthermore, they should generate the lowest possible vibrations suitable for the operation in full or partial vacuum. Therefore, the magnetic bearing turns out to be the optimal solution for this application.
  • Special centrifuges
    Special centrifuges and further physical test environments, such as the mechanical acceleration of particles.

Magnetic Bearing Demonstrator

Example of a magnetically levitated motor with 400,000 rpm for the operation of a rotating mirror in a high speed camera.

 

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Are you facing such a challenge in your company? We are excited to master it together with you. Do not hesitate to contact us.