Walter Bauer, Wolfgang Amrhein,
"Electrical Design Considerations for a Bearingless Axial-Force/Torque Motor"
, in IEEE Industry Applications Society, in IEEE Transactions on Industry Applications, 2013, ISSN: 0093-9994
Electrical Design Considerations for a Bearingless Axial-Force/Torque Motor
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The Axial-Force/Torque Motor establishes a completely new bearingless drive concept. The presented Lorentzforce type actuator features a compact and integrated design using a very specific permanent magnet excitation system and a concentric non-overlapping air gap stator winding. The endwindings of the bent air-core coils, shaped in circumferential rotor direction, provide active axial suspension forces. Thus, no additional (bearing) coils are needed for stable axial levitation. The four remaining degrees of freedom of the rotor are stabilized by passive magnetic ring bearings. This article concentrates on the determination of the lumped parameters for dynamic system modeling of the Axial-Force/Torque Motor. After introducing a coordinate transformation for the decoupling of the control variables axial suspension force and drive torque, the relations for coil dimensioning are developed followed by a discussion of the coil turn number selection process. Active levitation forces and drive torque specs. must both be fulfilled concurrently at nominal rotor speed with only one common winding system, respecting several electrical, thermal and mechanical boundaries likewise. Provided, that the stator winding topology is designed properly, a simple closed-loop control strategy permits the autonomous manipulation of both control variables. A short presentation of the first experimental setup highlights possible fields of application for the compact drive concept.