Permanent magnet air-cored tubular linear generator for marine energy converters

In this paper the authors outline the performance and modelling of a prototype linear tubular permanent magnet machine with an air cored stator. The main application of the machine is in direct drive marine energy conversion systems, where speeds are typically in the region of 0.5 m/s. A simple analytical method was derived to provide an initial design of a prototype machine, which was then modelled using 2D axisymmetric finite element analysis. Experimental results are presented to verify the design, and to investigate the performance of the machine as a generator.