As the act.ua.tors of active nlagnetic bearings (.41\IB) xre open loop mLstal,le a, feetll>;j.cli control system Ls esseiitia.1 for tlieir successfiil opera.tion aiid for ensuring good pesforniance. In addition, wlieii rotor sytenis utilizing ANBs a.re opera.t,ed a.t ligli speeds tliere mill be spclironous vilmkions due to nna.voidalde rotor niass milmlances. wliicli generate synclironans clisturlxuice forces. These forces and vibrations can often lead to severe prol,leiiLs in rotatiiig inadlines iiicluding collision d t l i t.lie toucli-Jowi lmi.riiigs at ligh speed and the possil,le risk of ca.u,?ing damage to tlie iiitenia.1 pa.rts of the ma.clines.hi this paper. a new "direct" achptire feetlforward algorithm is propasd for niiihiizing selected tilxat,ion peifonnance iiieasures wliich is Ixwetl on tlie filtered-x LSIS adaptive filter dgorit.lini. This new a.da.ptive algoorirhni lias l x e~ used for Adjusting t.he a.iiqditude and phase of a. sylichronous signal injected a.t tlie sunnnhig junction of the I,ea.ring fAbacli control loop. Tlie experimental results reported in tlis n-ork sliow the effectiveliess of tlie proposed met.liod.
A micro magnetic bearing actuator has been designed using electromagnets. In this design, the rotor position is actively controlled in the radial directions and passively supported in the axial direction. A micro position sensor, along with a proportional plus derivative (PD) control system, constitutes the feedback network, which ensures that the rotor is actively suspended in the radial directions. The circular stator has four control coils which are sandwiched between two stator end plates. The diameter of the stator and rotor are 2.1 and 2.6 mm respectively, while the thickness is fixed at 250 µm. The air gap between the stator and rotor has been fixed at 10 µm. The stator and rotor plates were fabricated using Permalloy electroplating, while the control coils of the stator were hand-wound using conventional coil winding techniques. The bearing components were assembled using normal micro assembly techniques. The details of the fabrication and assembly techniques employed for the micro bearings are presented, along with the test results.
We have successfully developed a one-degree-of-freedom microsuspension system, with active position control, as a paradigm of a micromagnetic bearing. This system integrates an electromagnetic actuator, a position sensor, and a feedback control system that provides active position control. This paper discusses the design and fabrication details of the microelectromechanical system (MEMS) components: the beam mass structure integrated with a drive coil and metallized targets, spacer plate, and sensor coils. It also discusses their integration with millimagnets and electronics. Noncontact magnetic bearings based on this principle have the potential of overcoming the tribo-physical issues associated with active MEMS devices.
[450]Index Terms-Beam mass structure, bidirectional actuation and control, electroplating, etching, feedback control, inductive sensor, magnetic actuator, magnetic microsuspension system, micromagnetic bearing, position sensor.
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