Magnetic bearings support rotating machinery without physical contact,
friction or wear. They require no lubrication, increase reliability, and especially reduce noise relative to conventional bearings. Magnetic bearings are also well suited to operate at higher temperatures, higher rotational speeds,
and extreme altitudes, and are hence a promising solution to current limitations. Magnetic bearings are increasingly being used in industrial machines such as compressors, turbines, pumps, motors, and generators.
This research describes high fidelity modeling of electromagnetic (EM) bearings with permanent magnets (PM) used to supply bias current. We analyze both the PM and EM parts of the system. Magnetic circuit theory is first used to gain insight into the magnetic forces and allows for the dynamic analysis of a rigid rotor coupled with the magnetic bearings. The results reveal that the magnetic forces are a strong nonlinear function of the rotor offsets from its equilibrium position. Next, the validity of the simplifying assumptions is examined with the aid of the finite element method. Comparisons of the magnetic forces are presented and discussed.
|
