Latching control strategies for improving performance of coupled linear-bistable wave energy converters

The global climate change and increasing renewable energy demand have fueled research interest in enhancing the capture performance of Wave Energy Converters (WECs) through control mechanisms. In this paper, a latching control mechanism is introduced into a coupled linear-bistable WEC system for the first time, to improve the capture performance and broaden the operating bandwidth. Based on the optimal command theory of Pontryagin maximum principle, three latching control strategies are proposed and numerically simulated. The analysis focused on the resonant frequency, capture performance and operational bandwidth of the coupled linear-bistable WEC under these control strategies, and compared the results with the condition without control (WO). Based on this, the impact of control strategies on the capture performance of coupled linear-bistable WEC is systematically compared by the relationship between control forces and floater's motions. The results show that the first-order resonant frequency of the coupled linear-bistable WEC is minimally affected by the control strategies, which significantly enhances capture performance in middle-low and high-frequency regions, leading to a broader operating bandwidth. Among the strategies, the Latching-Coupled Velocity (LCV) strategy exhibits the best control effect, with its effectiveness increasing with wave amplitude. These findings validate the feasibility and effectiveness of the three control strategies and provide valuable insights for integrating latching control mechanisms into complex coupled WEC systems.