Levitation Mechanism and Improvements of 3-DOF Deflection Type PM Actuator

The levitation mechanism of the 3-DOF deflection type permanent magnet actuator has been presented in this paper. The 3-D analytical model of the air gap between the rotor and stator is established under rotor eccentricity conditions. In order to figure out the unbalanced radial force with rotor static eccentricity, the models of the change of gap-length, air-gap flux density, and the radial electromagnetic force are simulated and calculated based on the analytical and finite element methods. According to the principle of the coordinate transformation and levitation force synthesis method, the current control model of the levitation force is established with the radial force distribution derived. The newly designed oil-film-based fluid suspension structure is also presented as improvements of this actuator. Finally, the analysis results have been validated by experiments of a prototype actuator system, which provides the foundation for the subsequent studies of this kind of actuators' levitation control system design.