Design and Construction of Permanent Magnet Linear Generator for Small-Scale Surface-Riding Wave Energy Converters

Wave energy converters (WEC) convert the energy from ocean waves into electricity. The surface-riding wave energy converter (SR-WEC) is a type of WEC that uses adaptive resonance to overcome the challenges faced by point absorber WECs. SR-WEC operates by using movable masses in the floating structure to adaptively change its natural frequency to match the incoming waves. The energy is captured using pitch motion of the SR-WEC. A tubular permanent magnet linear generator (PMLG) is used the energy from this pitch motion and convert it into electrical energy. The PMLG consists of a tubular stator on the outside and a moving permanent magnet translator inside. This work describes the development of a PMLG rated for 300N of power take-off force for use in a small-scale SR-WEC system. The design trends are illustrated through parametric two-dimensional finite element simulations results. Important practical design considerations of the prototype have also been discussed. Experimental analysis on the prototype design show that a good agreement between the simulated and measured values back EMF and phase currents of the PMLG. An actuated testbed was used to validate the performance of the PMLG. This work helps establish the proof of concept of PMLG designs for use in SR-WEC systems.