Severson to Present Tutorial on Magnetically Suspended Motors at ECCE

Eric Severson, Akira Chiba, Wolfgang Gruber, and Rafal Jastrzebski will hold a special tutorial at the IEEE Energy Conversion Congress and Exposition in Portland, Oregon on September 23rd, 2018.

ECCE 2018 Tutorial

Sunday, September 23rd

Portland, Oregon

 Title of Tutorial Lose Your Bearings: an Introduction to Magnetically Suspended Shafts


The goal of this tutorial is to train participants on how to use magnetic suspension in their motor systems in place of conventional bearings. In the first part of the tutorial, participants will analyze the shortcomings of conventional bearings, investigate case-studies highlighting applications where magnetic suspension systems are most advantageous, and survey commercially available solutions. In the second part of the tutorial, participants will explore the basic principles of magnetic forces and operation of both magnetic bearings and bearingless motors. Participants will apply these concepts to develop progressively more detailed design and control theory of this technology. Ultimately, participants will evaluate the potential for magnetic suspension technology to disrupt their product development or research field.

For magnetic bearings, the tutorial material will include the classical 4- and 8-pole heteropolar radial magnetic bearing as well as hybrid and homopolar magnetic bearings. Bearingless motors, where the magnetic field of a motor is modified to function as a magnetic bearing, are an up and coming technology that offers highly integrated designs with advantageous rotor dynamics and fewer components, but has seen little commercial deployment to date. The instructors will present recent research that enables bearingless motors to reach industrial power levels and/or ultra high rotational speeds through new combined winding technology, optimal machine design, and bearingless slice motor topologies.

In today’s motor systems, bearings are typically the first components to fail and can be a significant source of losses–especially at high rotational speeds. Furthermore, oil lubrication and hydrodynamic bearings require periodic maintenance, require bulky external pumping infrastructure, and oil seepage can contaminate and interfere with broader processes. Examples of critical problems caused by conventional bearings can be found in nearly every type of rotary system: from MW-scale HVAC chillers (where refrigerant contaminated by bearing lubricant reduces system efficiency by over 10%) to high speed dental drills (where the bearing lifetime is measured in 100s of hours) and flywheel energy storage systems (where bearings cause self-discharge due to drag and lubricants are incompatible with vacuum environments).

Recent developments in power electronic devices, embedded control systems, and magnetic materials are creating new and low cost opportunities for magnetic suspension systems. This is driving renewed industrial interest in magnetic bearings and bearingless motor technology.


  • Eric Severson University of Wisconsin-Madison,
  • Akira Chiba, Tokyo Institute of Technology,
  • Wolfgang Gruber, Johannes Kepler University, and
  • Rafal Jastrzebski, Lappeenranta University of Technology.