Proposal of a Linear Double-Stack Scattered Permanent Magnet Flux Switching Motor

Wave energy can be implemented by the development of low speed linear generators. For integration into devices with corrosion and fouling protection, they are likely to need high magnetic gaps. This gives a set of unique requirements for linear electrical machine design. In this study, three flux-switching type linear machines are compared, a single magnet per pole version, a dispositioned permanent magnet version and a biased flux topology. The suggested topologies are tailor-designed to operate at a low speed of O.5m/ s, determined by the wave speed, and feature a magnetic gap of 3mm, this is necessitated by the intention to integrate the machine into the wave energy converter, addressing the need for sealing and encapsulation requirements. In conventional flux-switching PM machines, since the PMs are wrapped with the armature winding, thermal management of PMs is not possible, and consequently, the demagnetization of the PMs is more probable. In the proposed flux-switching with dispositioned permanent magnets (FSDPM) topology, thanks to the dispositioned PMs, the PMs are protected from demagnetization. In the proposed inter-modular permanent magnet (IMPM) structure, the PMs are placed between neighbouring E-modules and are not wrapped with armature windings, so the PMs are far from the heating source and are completely protected from demagnetization. The presented topologies are optimized using a multi-objective genetic algorithm to obtain structures that offer the best characteristics in terms of thrust force and force ripple. The optimized structures are simulated using 2D finite element method (FEM), and the no-load and full-load performances of the presented topologies are obtained and compared in several aspects. It is suggested that the version with the distributed magnets results in a 10% increase in the force capability of these machines.