Response and Conversion Efficiency Optimization of the Floating-type Double-hinged Wave Energy Converter

A floating-type double-hinged wave energy converter (WEC) is designed to capture and convert wave energy. Its physics model is simplified with an incident angle of zero. Based on simplified cases where water waves are treated as linear, regular waves, the nonlinear coupled equations of the pitching-heaving motions, considering the damping moment, additional mass and addition inertia, are established using the Newton-Euler method. Through proper and effective pretreatment, the second order differential equation of pitching motion is derived. The mathematical analytic solutions reflecting response and conversion efficiency are deduced and discussed. Calculations indicate that the pitching motions of the two buoys can be considerd as simple harmonic motion with different phase angles. Both the damping coefficients of hydraulic energy conversion unit and buoy mass affect the amplitude-frequency response. The pitching angle and phase difference are key factors that affect the wave energy conversion efficiency. Their influence effects show some certain regularities. The efficiency-frequency curve always has a efficiency peak. The bigger damping coefficients will cause the greater wave energy conversion efficiencies. The appropriate ballast weight can promote the conversion efficiency significantly.