Dorota Kozanecka
Dynamics of the Flexible Rotor with an Additional Active Magnetic Bearing
Search for new solutions of bearing systems in modern rotary machines that have to
satisfy special performance demands has resulted in interest in rotor active magnetic
suspension systems. The application of active magnetic bearings (AMB) as a system of
the shaft suspension gives supplementary, unparalleled in classical solutions,
diagnostic capabilities. There are, however, also high requirements concerned with
the control system of the shaft position. The overall goal of an AMB controller
is to stabilise the plant and to reach the optimal technical performance. To
achieve these goals, AMB systems have to be optimised in an overall mechatronics
design approach. This leads to a new concept for control systems and actuators.
In rotor dynamics, the characteristics of bearings exert a decisive influence on modes
of vibrations and critical frequencies of the rotating shaft. This paper presents an
idea of programming a level of vibrations in the operating range of the rotating
system of the flexible rotor (including critical speeds) by using an additional
digitally controlled magnetic bearing. This causes a qualitative change in the
dynamic properties of the system. Some experimental investigations and numerical
simulations of flexible rotor dynamics carried out on the test stand with an
additional digitally controlled magnetic bearing are discussed. The experimental
characteristic curves of the start-up and shut-down have confirmed
possibilities of the programmable modelling of dynamics of the shaft line,
and - in prospect - of the designed machine that includes a magnetic bearing.
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