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1. (WO2005103517) ACTIVE MAGNETIC BEARING WITH AUTOMATIC DETECTION OF THE POSITION THEREOF

Pub. No.:    WO/2005/103517    International Application No.:    PCT/FR2005/000626
Publication Date: Nov 3, 2005 International Filing Date: Mar 16, 2005
IPC: F16C 32/04
F16C 39/06
Applicants: SOCIETE DE MECANIQUE MAGNETIQUE
TREMAUDANT, Yann
BRUNET, Maurice
SCHROEDER, Ulrich
Inventors: TREMAUDANT, Yann
BRUNET, Maurice
SCHROEDER, Ulrich
Title: ACTIVE MAGNETIC BEARING WITH AUTOMATIC DETECTION OF THE POSITION THEREOF
Abstract:
An active magnetic bearing (100) with automatic detection of the position thereof, comprising antagonistic first and second electromagnets (120, 130) forming stators disposed on both sides of a ferromagnetic body (110) forming a rotor maintained in a contact-free manner between said electromagnets. The electromagnets (120, 130) each comprise a magnetic circuit (121; 131), essentially consisting of a first ferromagnetic material and defining a gap with the ferromagnetic body, in addition to an exciting field (122; 132) which is fed by a power amplifier whose input current is controlled according to the position of the ferromagnetic body in relation to the magnetic circuits of the electromagnets. The position of the ferromagnetic body (110) is measured from the inductance detected between the two electromagnets (120, 130) reacting to the simultaneous injection into the two antagonistic electromagnets of a sinusoidal current having a frequency which is higher than the bandwidth in a closed loop of the system. The magnetic circuit (121; 131) of each electro-magnet also comprises a portion (124; 134) in the vicinity of the exciting field coil (122; 132) using a second ferromagnetic material whose magnetic permeability is lower than that of the first material and whose electric resistivity is greater than that of the first material in order to promote the passing of high frequency magnetic fields generated in the bearing.