초록 ▼

A rotary motor and a rotary magnetic bearing are integrated in a compact assembly that is contact-less. A stator assembly surrounds a ferromagnetic rotor with an annular air gap which can accommodate a cylindrical wall, e.g. of a chamber for semiconductor wafer processing. The stator assembly has a

A rotary motor and a rotary magnetic bearing are integrated in a compact assembly that is contact-less. A stator assembly surrounds a ferromagnetic rotor with an annular air gap which can accommodate a cylindrical wall, e.g. of a chamber for semiconductor wafer processing. The stator assembly has a permanent magnet or magnets sandwiched between vertically spaced magnetic stator plates with plural pole segments. The rotor is preferably a ring of a magnetic stainless steel with complementary pole teeth. The stator assembly (i) levitates and passively centers the rotor along a vertical axis and against tilt about either horizontal axis, (ii) provides a radial position bias for the rotor, and (iii) establishes a motor flux field at the rotor poles. Polyphase coils wound on the stator plates produce a rotating flux field that drives the rotor as a synchronous homopolar motor. A rotor without pole teeth allows operation with an asynchronous inductive drive. A controller energizes control coils wound on each stator pole segment in response to a sensed physical position of the rotor. The control coils provide active radial position control and can actively damp tip and tilt oscillations that may overcome the passive centering.

대표청구항 ▼

[ What is claimed is:] [1.] A method for levitating a mass and rotating the mass about a vertical z-axis with a motor having a stator assembly and a rotor, the rotating occurring without frictional contact between the stator assembly and the rotor, which have an air gap therebetween, said method com

[ What is claimed is:] [1.] A method for levitating a mass and rotating the mass about a vertical z-axis with a motor having a stator assembly and a rotor, the rotating occurring without frictional contact between the stator assembly and the rotor, which have an air gap therebetween, said method comprising:forming the rotor as a ring of ferromagnetic material having a high magnetic permeability, said ring comprising a vertical portion extending along the z-axis and a horizontal portion extending perpendicular to the z-axis,levitating and centering the rotor with respect to the stator assembly along the z-axis with a stator magnetic flux field comprising a DC flux field, which also centers the rotor against tilt out of a plane orthogonal to the z-axis, said DC flux field originating at the stator assembly,simultaneously radially biasing the rotor with said stator magnetic flux field,simultaneously inducing a flux field in said rotor with said stator magnetic flux field applied across an air gap through said horizontal portion of the ring,driving the rotor to rotate about the z-axis using a rotating electromagnetic field produced by the stator assembly and applied across the air gap, the rotating electromagnetic field interacting with said flux field induced in the rotor by said stator magnetic flux field,sensing at least a radial position of the rotor with respect to the stator assembly, andadjusting the stator magnetic flux at angularly spaced regions about the stator assembly in response to said sensing to maintain a spacing between said rotor and said stator assembly during said driving.