Abstract:
Active Magnetic Bearing system (AMB) is a mechatronic device which is used to
levitate rotating parts of a machine without contact to the stationary part of the
machine. It has nonlinear characteristic, multi-input multi output and unbounded input
output systems. The non-linearity properties should be coming from the relation
between force, current and position of the rotor. Due to those characteristics, it is
challenging for the system stability. In order to maintain a stable and good
performance; controllers must be designed as part of the system. The mathematical
model was developed and it shown that the AMB system considered as a 2X2 MIMO
system. In order to reduce the complexity of the system, the nonlinear model is
linearized by appropriate linearization method. The advantage and application area of
active magnetic bearings has been defined. The simulation results were carried out by
Matlab/Simulink version 2018a.
In this thesis, Neuro fuzzy sliding mode controller has been designed for control the
position of active magnetic bearing system. Matlab Simulink models of AMB with
SMC, FSMC and NFSMC are developed to carry out simulation studies. The
comparison results show that with SMC; the position of the rotors is following the
reference input but it affected by chattering. It is further observed that the FSMC are
reduced the chattering, and also NFSMC controllers are eliminate automatically the
chattering problem and it is more robust and smoothly operate. The stability of the
system has been analyzed by using Lyapunov theorem. The simulation result show
that the overall system output performance can be improved using the proposed
controller, the NFSMC resulted no overshoot, small settling time(0.5sec) and less rise
time (0.10 sec) as compared to 0.392%, 0.75sec and 0.133sec for FSMC controller,
and 9.047%, settling time 7.5sec and rise time 0.17sec for existing SMC.
Key words: Active magnetic bearing, neural network, fuzzy logic, sliding mode
controller, Matlab/Simulink