Multistable Pendulum Wave Energy Harvesting under Multidirectional Irregular Excitations

This work reports a gimbaled-pendulum wave energy converter with a magnetic multistable mechanism to better capture multidirectional irregular excitations. To have a deep insight into the multistable effect, the dynamic energy conversion is modeled by taking random excitations from multiple directions into account. Moreover, this work investigates the effect of hull swing on the distribution of equilibrium points and potential wells and analyzes the promotion of energy harvesting performance under different excitations. It is found that the average output power is increased by 6.5% under the sway excitation and by 51.1% under the roll excitation with the help of the multistable mechanism. A scalable prototype occupying a space of 0.029 m
³
in total is fabricated. Field results under mild sea condition show that the wave energy converter can output electrical power with the peak value of 3.83 W and average value of 0.295 W, while the corresponding root mean square amplitudes of the roll and pitch vibrations of the hull are as small as 3.52° and 3.07°. Potential approaches for enlarging the electrical output are also discussed.