Electromagnetic Propulsion, Suspension and Levitation – New Concepts of Bearingless Systems for High-Precision Industry


Talk by Prof. Elena Lomonova

 Magnetically levitated planar motors are the best candidates of the electromagnetic motion systems for wafer scanners in the lithographic industry because of their clean-room and vacuum compatibility. Using the magnetic fields for bearingless motion concepts, they have to be controlled actively in six degrees-of-freedom for stable operation. Therefore, all force and torque components acting on the translator should be accessible and be decoupled. Typically, they provide the long stroke xy-movements, a short stroke along the z-axis, and small rotations around all axes. High-precision bearingless planar motors with magnetic levitation and sub-micrometer accuracy are usually of PM synchronous type. In contrast to these levitated planar motors, a novel enabling magnetic suspension system underneath a stationary frame – elevated propulsion stage is developed. It requires an attractive normal force between the frame and the translator to counteract the gravitational force, whereas magnetic levitation above a stationary frame is based on a repulsive normal force. In this respect, basically many topologies (synchronous PM, induction, reluctance ones) are applicable. Several possible topologies for both concepts of bearingless magnetically levitated and suspended systems are treated, a thorough electromagnetic analysis, and several design and performance criteria are discussed. The decoupling techniques for force and torque components are demonstrated with the aim to realize an active magnetic bearing principle. Additionally, the symmetrical propulsion behavior along x and y axes, and wireless energy transfer from the stationary platform to the moving platform are demonstrated. All theoretical findings are verified with experiments of fully operational magnetically levitated and suspended stages. 

  Date and Time




  • Date: 21 Feb 2020
  • Time: 08:30 AM to 09:30 AM
  • All times are Europe/Zurich
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Talk at ETH, Zurich (before COVID restrictions).

  • ETH Zurich - Physikstrasse 3
  • Zurich, Switzerland
  • Switzerland CH-8092
  • Building: ETL
  • Room Number: H23


Prof. Elena Lomonova