Laboratory tests of linear electric machines for wave energy applications with emulation of wave energy converters and sea waves

As in other renewable and non-controllable sources of energy, in the case of ocean wave energy the use of electrical linear generator as direct drive power take-off (PTO) in a wave energy converter (WEC) provides several advantages such as improvements in the versatility of control, in the robustness and in the efficiency for a wide range of loads. This paper describes a laboratory test facility of linear electric machines which work as direct-drive PTO in WEC and the obtained results in the case of a Linear Wave Energy Generator based on a linear switched reluctance machine (LSRM). The lab testing scheme does not use external hydraulic or pneumatic actuators but splits the coils of the LSRM in two parts (two sub-machines) controlling them by means of two power electronics converters. This configuration does not permit testing the nominal power, force nor velocity of the LSRM but does permit controlling one sub-machine as WEC emulator and the other as the generator also permits testing and comparing different strategies of wave energy capture. LSRM tests under realistic ocean conditions, such as irregular waves, will also be possible with this method.