Comparative study of inner and outer rotor hybrid excited flux switching generator for wave energy

Wave energy represents one of the most abundant and underutilized renewable energy resources, offering substantial potential to reduce global dependence on fossil fuel–based energy systems. Despite its promise, the practical exploitation of wave energy remains technically challenging, hindering its widespread deployment. This study presents a comparative electromagnetic analysis of inner-rotor and outer-rotor flux-switching permanent magnet (FSPM) generators designed for direct-drive wave energy conversion at a low operating speed of 30 rpm. To ensure a fair comparison, both topologies are designed with identical volumes of ferrite permanent magnets and magnetic materials. Two-dimensional finite element analysis (2D FEA) is employed to assess key performance metrics, including power density, efficiency, and flux characteristics. The results indicate that the outer-rotor configuration exhibits superior performance, achieving higher power density and efficiency, primarily due to its enhanced air-gap flux density and improved flux regulation capability. Both generator designs demonstrate strong potential for application in low-speed, direct-drive wave energy systems.