Enhancing efficiency of a point absorber bistable wave energy converter under low wave excitations

In this study, an improved magnetic bistable mechanism is proposed to enhance capture efficiency of a point absorber wave energy converter (WEC), and it can improve the ability of energy harvesting for the conventional bistable WEC under low wave excitations. The improved magnetic bistable mechanism consists of three pairs of magnetic rings. The numerical simulations are carried out to study the dynamic characteristics and energy absorption. Time domain method, referred as the Cummins’ equation, is adopted to calculate the nonlinear responses of the bistable WEC. The reasonable design domain for the key parameters of the permanent magnets is suggested. The characteristics of wave energy capture are analyzed in details in comparison with the three types WECs (linear WEC, conventional magnetic bistable WEC and improved magnetic bistable WEC). The results show that the improved magnetic bistable mechanism can greatly broaden the bandwidth of energy absorption and increase the absorption efficiency especially under low wave excitations. •The usage of a nonlinear power capture mechanism to enhance efficiency is studied.•A novel magnetic bistable mechanism is proposed and applied to a point WEC.•The novel bistable device dramatically increases efficiency.•The bistable device broadens the frequency bandwidth especially in low excitation.•The bistable device has significant potential applications in wave energy utilization.