Self-powered transformer eddy current damper for vibration control of rotors

The vibration control of rotors is usually performed using passive dampers, in layouts where the support of the rotating parts is achieved by rolling-element or hydrodynamic type bearings. Active magnetic bearings could be a promising however they show serious drawbacks, in terms of mass, at least when the generation of strong magnetic forces is required. Electromagnetic dampers seem a valid alternative to viscoelastic/hydraulic dampers and to active magnetic bearings because their simpler architecture, and, if of transformer type, also for the absence of power electronics, position sensors and any fast feedback loop. However transformer eddy current dampers require a constant voltage power supply (usually based on common power electronics) often integrated with active electronics components. To reduce cost, improve the reliability some applications could benefit a simplified system avoiding active components and providing the required energy with an embedded generator. The aim of the present paper is to propose a self-powered damper to fulfil these requirements. A three-phase permanent magnet electric generator (connected to the rotating shaft) generates the required power for the damping device. The generator is connected to the damping circuit by means of suitable impedance and a three-phase rectifie