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Abstract

Permanent magnets are vital parts of various devices, above all, those which are essential for the transition to a green society. However, they are made of materials, including rare-earth elements, for which unlimited availability cannot be taken for granted. Therefore, it is desirable to reduce the content of these materials but without affecting the technologically relevant properties. Whereas the conventional solution to this problem is an appropriate material modification, the subject of this thesis is an alternative approach, i.e., a custom design for a particular application to use less material without losing performance. The focus is on the permanent magnet as a source of magnetic field in an induction-based self-charger for portable devices. It is supposed that the required magnetic-flux time dependence is achieved either with an oscillating magnet and a static coil or with a static magnet and an oscillating coil.
The performance indicator is the average induced voltage normalized to the magnet volume, theoretically predicted by applying the finite-element method. The innovation is notches in the considered magnets, which make the resulting field sufficiently inhomogeneous even in the case of a uniform, uniaxial magnetization, and which simultaneously contribute to a smaller volume, and hence to reduced material consumption.
To determine the most appropriate geometrical parameters of the magnets, an optimization analysis is conducted. Basically, the considered magnet geometries are characterized by three pa-rameters, of which two are optimized simultaneously while the third is kept fixed. The obtained sets of optimum parameters yield better results than arrangements of standard magnets with non-trivial magnetization patterns, proving the advantages and applicability of the proposed problem solution.