Satcon Technology Corporation

Shankar Jagannathan

Richard L Hockney

Vijay M Gondhalekar

David B Eisenhaure

James R Downer

William E Stanton

Stephen B Nichols

Kevin Leary

Ralph C Fenn

Kevin J Leary

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.

Integrated magnetic levitation and rotation system

A very light, high force reaction-mass actuator using high energy density magnetostrictive material to accelerate a mass, producing a reaction force that can be used to oppose vibration forces. The reaction-mass actuator is configured having an axially symmetric design that features a Terfenol-D rod as a core. Surrounding the rod is a magnetic coil which provides the changing magnetizing field used to actively control magnetostrictive strain of the Terfenol rod. The magnetic coil also provides a magnetic flux based on a D.C. current, for biasing the Terfenol rod. The magnetic coil, disposed about the fixed magnetostrictive rod, is incorporated into a reaction mass assembly that is suspended and sealed inside an enclosed, stiff outer shell or housing by an elastomeric material mounting configuration that facilitates an output force with suppressed harmonic content. In addition, the elastomeric mounting configuration provides sealing protection against external factors. In one embodiment, the magnetic coil is wound on a bobbin effecting a movable mass that is accelerated to produce a force on a mounting surface. The Terfenol rod is placed under axially compressive stress by a simple mechanical preloading mechanism. This increases strain in the Terfenol rod while providing a return spring for the reaction mass when it has reached its maximum stroke.

Light reaction mass actuator

Growing community of inventors

Waltham, MA, United States of America

Shankar Jagannathan