Energy conversion efficiency assessment of a direct drive wave energy converter with different current controllers

Linear permanent magnet generators are commonly used as the power take-off system in direct drive wave energy converters. The electrical power generated is characterized by a high variability in amplitude and frequency, so a power electronic interface is needed for grid connection. In addition to its coupling function, the electronic converter can be used as a tool to improve the efficiency of the wave energy conversion. An approach to this goal is to use the generator-side converter to emulate a resistance as seen from the generator. For this optimization method, this paper describes the performance of three different current controllers of the converter from the point of view of the overall conversion efficiency.