Integrated Radial and Axial Low Cost Compact A.M.B.

Usually the rotor is levitated by one axial and two radial bearings which are arranged separately around the rotor. Often, the effective bearing length has to be limited. This is due to the requirements of the construction and the application. With respect to the rotor dynamics it is also advantageous to minimize the rotor length especially at high speed rotating machinery. The paper describes an integrated axial-radial compact active magnetic bearing designed as a homopolar bearing. Compared with a standard bearing of similar capacity the design shows some advantages in size, losses, and costs. The arrangement combines the axial and radial capacity and the auxiliary bearing landing system compactly within one unit. Thereby, the lateral surface of the axial disk is used as rotor core for the radial bearing. The four stator cores consist of standardized lamination. The rotor is not laminated. Design, manufacturing, and testing of this bearing have been completed successfully. The compact bearing is integrated into the new test facility MBZ120 with a complete magnetic supported rotor. The load capacity amounts to 120 N axially and to 60 N radially. The second radial bearing is also constructed as a homopolar bearing. The bearing control can be realised very simply and robustly without or with variable bias current. A special design allows different bearing positions on the rotor for vibration tests. The paper presents selected bearing test results.