Authors: Peihao Chen, Dawei Wu, Yiqing Yang, Yan Zhang, Athanasios Tsolakis, Karl Dearn

 

Abstract:

Current hybrid wave–tidal energy conversion technologies remain inadequate in fully leveraging the complementarity between wave and tidal energy, limiting overall efficiency and output stability. Moreover, conventional modeling approaches rely on idealized continuous sinusoidal wave inputs, making them unsuitable for capturing real ocean conditions or performing time-domain analysis. To address these gaps, this study proposes a hybrid wave-tidal energy converter (HWTEC) featuring a nonlinear motions rectification and coupling device (NLMRCD). Within the NLMRCD, a mechanical motion rectifier (MMR) converts reciprocating wave motion into unidirectional rotation, mitigating energy loss from frequent motion reversals. A bevel gearbox with one-way clutches couples wave and tidal energy inputs, enhancing power continuity and increasing voltage output. A novel discretization modeling methodology is developed to characterize the nonlinear interaction between wave and tidal modules. It accepts discrete input data and automatically identifies overrunning phases, simplifying time-domain calculations without requiring continuous input functions. Simulations under ocean-like conditions yield a peak power output of 18.72 W and an efficiency of 60.94 %. Experimental validation on a custom dual-input test bench confirmed these results, achieving 19.65 W and 61.34 %, respectively. The NLMRCD enhances output power and voltage stability by coupling intermittent wave and tidal energy, thereby improving system usability and conversion efficiency. The proposed discretization modeling approach overcomes limitations of continuous inputs in traditional methods, and offers a robust framework for simulation using measured wave data.

 

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