Reluctance actuators (RA) are a type of electromagnetic actuator that offer high
forces for short range motions. The RA takes advantage of the electromagnetic reluctance
force property in air gaps between the stator core and mover parts. The
mover accelerates because the stator generates the magnetic flux that produces an
attractive magnetic attraction between the stator and mover. Hysteresis and other
non-linearities in the magnetic flux have an impact on the force and have a nonlinear
gap dependency. It is demonstrated that the RA has the capacity to produce a
force that is effective and suitable for millimeter-range high-acceleration applications.
One application for the RA is the short-stroke stage of photolithography machines
for example. The RA is available in a wide variety of configurations, such as CCore,
E-Core, Maxwell, and Plunger-type designs. The RA requires precise dynamic
models and control algorithms to help linearize the RA for better control and optimization.
Some nonlinear dynamics include magnetic hysteresis, flux fringing, and
eddy currents. The RA is shown to have a much higher force density than any other
traditional actuator, with the main disadvantage being the nonlinear and hysteretic
behaviour which makes it hard to control without proper dynamic and control models
in place. It is important to model the RA accurately for better control. The output
force can be significantly impacted by unequal offsets or asymmetries between the
mover and stator. In the thesis that follows, a review of RA systems is performed, an
investigation that shows the importance of including the mean path length (MPL)
term for higher accuracy, a technique for calculating the force of various asymmetrical
instances for the C-core RA is demonstrated. This thesis documents currently available
knowledge of the RA such as available applications, configurations, dynamic
models, measurement systems, and control systems for the RA. The findings presented
can allow for future control systems to be designed to counteract multi-axial
asymmetric issues of the RA
