This thesis addresses the design of ferrite cores for inductive proximity
sensors of the ECKO type. The purpose of this pursuit is to identify several ferrite
cores that have the highest performance in terms of the sensor's sensing ability.
The purpose of the ferrite core in these sensors is to concentrate and focus
the alternating magnetic field produced by a current-carrying winding. The
magnetic flux is specifically aimed at the sensor's metal target, and since the
sensing operation is dependent on the generation of eddy currents within the metal
target, the range at which the target can be detected is a direct function of how
optimally the magnetic flux is cut by the target. In this study the target is a
circular disk, just as is used in industry for standardization procedures.
To begin with, a theoretical analysis is performed to identify those factors
that affect sensing performance; this development makes use of fundamental
electromagnetic theory. Subsequently, the performance of a score or so ferrite
geometries is evaluated by computer simulation using the results of the theory to facilitate effective comparison. The computer simulation is performed using finiteelements
based electromagnetics solver software from ANSOFT.
Lastly, some of the geometries studied with the simulation are constructed
and their sensing performance evaluated as verification of the simulation and its
theoretical backing.
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