Active magnetic bearing with auto position-detection

US5844339A · kind A · utility

Assignee

• SOCIETE DE MECANIQUE MAGNETIQUE · FR

Inventors

• Ulrich Schroeder · Braunschweig, DE
• Maurice Brunet · Auxerre, FR

Key dates

• Filing date: Aug 27, 1996
• Grant date: Dec 1, 1998
• Expiry date: Aug 27, 2016

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F16C32/0448
• WIPO field: Mechanical elements
• WIPO sector: Mechanical engineering

Abstract

An active magnetic bearing with auto position-detection includes first and second opposing electromagnets disposed on opposite sides of a ferromagnetic body (1) suspended without contract with the electromagnets. The bearing includes inductive type position detectors which are constituted directly by coils (11, 21) of the first and second electromagnets. A mechanism (14; 24) is provided for injecting a sinusoidal current I.sub.0 sin.omega.t of constant amplitude I.sub.0, of angular frequency .omega., and of identical phase, simultaneously to the inputs of power amplifiers (13, 23) powering the coils (11, 21) of the first and second opposing electromagnets in superposition with the main currents from the servo-control circuits (31, 32). Circuits (41 to 44) serve to extract the position information which determines the magnitude of the main current to be applied by the servo-control circuits (31, 32) to the power amplifiers (13, 23) directly from the voltages u.sub.1, u.sub.2 across the terminals of the excitation coils (11, 21) as measured at the frequency of the sinusoidal current constituting a carrier of angular frequency .omega..