Constrained control design of magnetic bearing systems

2004 ◽  
Author(s):  
Tingshu Hu ◽  
Zongli Lin ◽  
Wei Jiang ◽  
P.E. Allaire
Keyword(s):  
Control Design ◽  
Magnetic Bearing ◽  
Constrained Control

Constrained Control Design for Magnetic Bearing Systems

2005 ◽  
Vol 127 (4) ◽  
pp. 601-616 ◽  
Author(s):  
Tingshu Hu ◽  
Zongli Lin ◽  
Wei Jiang ◽  
Paul E. Allaire
Keyword(s):  
Systematic Approach ◽  
State Constraints ◽  
Control Design ◽  
State Constraint ◽  
Magnetic Bearing ◽  
Constrained Control ◽  
Balance Beam ◽  
The Stability ◽  
Safety Operation ◽  
Input And State Constraints

We study control problems in magnetic bearing systems that are subject to both input and state constraints. Apart from the usual restrictions on voltages and currents in the circuit systems, most magnetic bearing systems are subject to a severe state constraint: the motion of the rotor (the suspended object) is only allowed in an extremely small airgap, otherwise the collision of the rotor and the stator would cause severe damages. Traditional methods for avoiding a collision include increasing the airgap and increasing the currents, which would usually result in unnecessarily large capacity of power supply and power loss. In this paper we present a systematic approach for dealing with all the input and state constraints by using some recently developed tools for constrained control design. Issues on the stability region, robustness, disturbance rejections, and transient response are addressed. We hope that by dealing with the constraints properly, safety operation can be ensured with relatively small currents and power consumption. Experiments on the balance beam test rig in our laboratory show that the design techniques are effective.

Three Practical Examples of Magnetic Bearing Control Design Using a Modern Tool

2002 ◽  
Vol 124 (4) ◽  
pp. 1025-1031 ◽  
Author(s):  
M. Spirig ◽  
J. Schmied ◽  
P. Jenckel ◽  
U. Kanne
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Control Design ◽  
Industrial Applications ◽  
Magnetic Bearing ◽  
Engineering Practice ◽  
Digital Implementation ◽  
Bearing Characteristic ◽  
Multistage Centrifugal Compressor ◽  
Modern Tool

The use of magnetic bearing in industrial applications has increased due to their unique properties. Nowadays efficiency and predictability in handling rotors on magnetic bearings is asked with the same standard as conventional rotors on oil or roller bearings. First of all one must be aware of the special technical properties of magnetic bearing designs. The dynamic behavior of the rotor combined with requirements of the application define the desired bearing characteristic. With modern tools covering the mechanical aspects as well as the electronic controllers and their digital implementation on a DSP, these properties can be designed. However, despite the use of such efficient tools engineering practice is needed. Therefore this paper summarizes the major steps in the control design process of industrial applications. Three rotors supported on magnetic bearing with their specific dynamic behavior are presented: a very small high speed spindle (120,000 rpm); a small industrial turbo molecular pump rotor (36,000 rpm); and a large multistage centrifugal compressor (600 to 6300 rmp). The results of the analyses and their experimental verification are given.

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