Magnetic Suspension Systems with Active Magnetic Bearings

Active magnetic bearings (AMB) are constructed with electromagnets whose coil currents are usually controlled via feedback laws. AMBs have several appealing advantages over traditional
bearings, such as very low power-loss, very long life, elimination of oil supply, low weight, reduction
of fire hazard, vibration control and diagnostic capability. They have been utilized in a variety of
rotating machines ranging from artificial heart pumps, compressors, high speed milling spindles,
flywheel energy storage systems to maglev trains. 

Magnetic suspension systems with AMBs are typical examples of control systems with severe
constraints such as very small clearance and low power loss. An open-loop magnetic suspension
system is intrinsically unstable and nonlinear. They can be constructed as benchmark experimental
systems for educational purpose and for testing new control design techniques. 

We are currently constructing a magnetic suspension system at Umass Lowell.

1. T. Hu, Z. Lin and P. Allaire, ``Power-loss reduction by optimizing current allocation 
   in magnetic bearings,'' IEEE Transactions on Magnetics, Vol.40, May, pp.~1625-1635, 2004.  
2. T. Hu, Z. Lin, W. Jiang and P. Allaire, ``Constrained control design of magnetic 
   bearing systems," ASME Journal of Dynamic Systems, Measurement and Control, Vol.127, No.4, pp.601-616, 2005.
3. T. Hu, Z. Lin, P. E. Allaire, "Controller design of magnetic suspension in artificial 
   heart pump,"  the 9th International Symposium on Magnetic Bearings.