Electrical generators for direct drive wave energy converters

TLDR

Wave power devices typically use conventional rotary electrical machines, but converting the low‑reciprocating motion of the device to 1500 rpm rotation requires hydraulic systems or air turbines. The study introduces a direct‑drive system that drives a reciprocating electrical machine at the same speed as the wave device. The authors compare a linear permanent‑magnet synchronous machine to a transverse‑flux machine in a basic design study and develop electromagnetic and circuit models to evaluate the transverse‑flux machine’s performance in a wave energy converter. The transverse‑flux machine is identified as having the best potential, and the authors suggest measures to optimize its performance.

Abstract

Wave power devices traditionally use conventional rotary electrical machines for power conversion. However hydraulic systems or air turbines are required to convert the low reciprocating motion of the wave device to rotation at 1500 rpm. The concept of a direct drive system is introduced, in which a reciprocating electrical machine is driven at the same speed as the device. A linear permanent magnet synchronous machine is compared to the transverse flux machine in a basic design study for this application. The latter machine is identified as offering the best potential. Electromagnetic and electric circuit models are developed to investigate the performance of the transverse flux machine in a wave energy converter. Measures are suggested to optimise the performance of the machine..