Affiliations: [a] Fast Reactor Technology Group, Indira Gandhi Center
for Atomic Research, Kalpakkam, Tamil Nadu, India | [b] Department of Electrical Engineering, IITM, Chennai,
India
Correspondence:
[*]
Corresponding author: S.K. Dash, Fast Reactor Technology Group,
Indira Gandhi Center for Atomic Research, Kalpakkam, Tamil Nadu 603102, India.
Tel.: +91 44 27481500 (21032); Fax: +91 44 27480086; E-mail: skdash@igcar.gov.in
Abstract: Magnetic Bearing, especially Active Magnetic Bearing (AMB) is
arguably most preferred bearing for the process dealing with highly reactive
environment, high speed operation and where the process required least
contamination. They are also being tried for Fly wheels and Wind generators.
They continue to be evolved since last several decades. Quite a few processes
like application of AMB in high temperature Liquid Sodium high temperature
applications call for development of large-working-gap active magnetic bearings
(AMB). Smooth operation of AMB depends on hypersensitive position stiffness and
Current stiffness, which fluctuates due to differential-thermal-expansion
induced air gap variation. So, large gap, necessitates flatter open loop
position stiffness than that of contemporary magnetic actuators. In this work,
a goal seeking optimization methodology is employed for double acting AMB
system where a combination of higher (CRGO electrical steel) and lower
saturating magnetic material (Mu metal) is used. A less variant position
stiffness across the air gap was arrived at after getting optimized design
variables constituting geometry and excitation current parameters. This
investigation opens up a new way to attain position stiffness in AMB system
which is less sensitive to positional variation of rotor in air gap. This paper proposes an innovative and first-of-its-kind bi-material core material with
goal driven optimized magnetic actuator design which can afford to have air gap
variation during operation.
Keywords: Thrust magnetic bearing, position stiffness, goal driven optimization, evolution strategy, bi-materialactuator
