In order to enhance the capture efficiency and broaden the bandwidth, a novel rotation Power Take-off with nonlinear stiffness is proposed and applied to a traditional raft-type wave energy converter (WEC). Refer to Cummins’ equation, the governing equations of motion for a WEC with nonlinear stiffness in the time domain is established based on linear hydrodynamic model. The harmonic balance method is employed to solve the set of nonlinear dynamic equations. The characteristics of the wave absorption in regular and irregular waves are analyzed by using numerical simulations. The effects of the systematic parameters and wave conditions on wave energy capture efficiency are analyzed. The numerical results show that the nonlinear stiffness mechanism with appropriate parameters can enhance capture efficiency and broaden frequency bandwidth of the energy capture. Robust performance improvement without complex nonlinear phenomena of jumping and multiple solutions is revealed by using the analytical solutions. The nonlinear stiffness mechanism can provide a role of phase control for the raft-type WEC.

为了提高捕获效率并拓宽带宽，提出了一种具有非线性刚度的新型旋转取力器并将其应用于传统的筏式波浪能转换器（WEC）。参考康明斯方程，基于线性流体动力学模型建立了时域非线性刚度WEC的运动控制方程。采用谐波平衡法求解非线性动力学方程组。通过数值模拟分析了规则波和不规则波的吸波特性。分析了系统参数和波浪条件对波浪能捕获效率的影响。数值结果表明，具有适当参数的非线性刚度机制可以提高捕获效率并拓宽能量捕获的频率带宽。使用解析解揭示了没有跳跃和多解复杂非线性现象的稳健性能改进。非线性刚度机制可以为筏式 WEC 提供相位控制的作用。