Conceptual Design of a Linear Power Generator for Undulator-Type Tidal Current Power Generation

Recently, a tidal current power generator system we call an “undulator-type tidal current power generator”, being developed in which a linear power generator is attached to a membrane that undulates like a fish fin when subjected to tidal currents. This unique mechanism, which does not have a rotating turbine, has the potential to solve the problems that hinder the practical application of tidal current power generation, but requires a small, high-power linear power generator to make it work. For this purpose, we came up with a multilayered Halbach array, which we used as a field pole magnet and HTS bulk as a flux collector. In this structure, the magnetic field emitted from the Halbach array on the celling and bottom is induced by the HTS bulks fixed in the middle layer and penetrates the armature coils. In particular, to obtain a large output from the armature, we have developed a new type of coil that effectively wraps an iron core, improving on the vortex-type coils used in our axial-gap type HTS rotating machines, in which copper wires are tightly wound to the center. This compact linear power generator with permanent magnets and HTS bulk magnets combining a multilayered Halbach array and multilayered iron core coils has shown the potential to generate very large output power under low speed and short stroke conditions and is expected to be used for tidal power generation in the future.