Modeling and Control of an Active Magnetic

Abstract

Active Magnetic Bearings (AMB) support a
body by magnetic pulling forces, without any mechanical
contact. The main advantages of such bearings compared
with the traditional solutions are: absence of mechanical
friction and wear, lubricant-free operation and therefore
suitability for severe environments and applications, active
vibration control and unbalance compensation. This paper
deals with modeling and simulation of radial active
magnetic bearing system in a high-speed drive. The system
model from previous works [1], [5] has been extended with
model of the power amplifier with PWM control. Hence,
dynamic behavior of currents in the bearing windings can
also be investigated with this model. Two different
controllers are used in the work, i.e. PID and state-space
controller. Both will be compared to each other for two
cases: a) lift-off of the rotor, and b) unbalance in the rotor
which causes periodical disturbance force, which has also
to be compensated by the magnetic bearing, additionally to
the gravitation force