Performance analysis of butterfly wings wave energy converter

This paper proposes a new Butterfly Wings Wave Energy Converter (BWWEC). Two wings are always pitching to absorb the wave energy. Yaw tail is designed to make two wings be positive to incoming waves, and planetary is used to couple two wings' torque to drive generator. The maximum extraction strategy is proposed by the regulation of pitch speed, which is controlled to approach to the wave speed by the PI Tracking controller. Using the hybrid method of differential element and virtual wave extension, the infiltration volume and surface area are solved and then gives the buoyancy and excitation force torque, with which two wings pitch dynamic model is finished with the consideration of wings' pitch, torque coupling and the generator speed control. Through the simulation study, the extraction ability of BWWEC has been validated, and reveals the importance of the regulation of the load torque. The instantaneous absorbed energy can reach a maximum wave energy of approximately 95%, which is decided by the extent to the approximation between the BWWEC pitching speed and wave speed, and the device can efficiently extract energy from the wider range of periods.