Hybrid bearing for induction machine with controlled electromagnetic positioning and superconducting levitation

A frictionless electromagnetic-superconducting hybrid bearing for induction machine has been designed and is currently in development and tests. The vertical and radial stiffnesses have been investigated by dynamic method for different air gaps of the axial superconducting bearing. The measured low value of the radial elastic constant appeared to be responsible for the instability of the rotating shaft. That instability has been controlled using double motor-bearing devices assembled on the same shaft. This fully frictionless system reached a spinning speed of 6300 RPM.