A Piezoelectric–Electromagnetic Low-Frequency Wave Energy Harvester Based on L-Shaped Beam and Upconversion Mechanism

Ocean waves are characterized by low frequencies, and energy harvesters typically require higher frequencies for optimal performance. Therefore, improving output performance in low-frequency wave environments is a problem that needs to be solved for today’s wave energy harvesters. In this paper, a piezoelectric–electromagnetic low-frequency wave energy harvester (PEWEH) is proposed. The PEWEH design utilizes an L-shaped beam to reduce the intrinsic frequency of the system and employs gearing and multiple magnets to increase the excitation frequency. The unique solution for low-frequency wave energy harvesting utilizes a combination of multiple upconversion mechanisms with L-shaped beams and drive frequency boosters. Simulation and experimental analyses identified key factors influencing the output performance. Under optimal conditions, the system achieved maximum voltage of 70.62 V for the piezoelectric energy harvester (PEH) and 1.508 V for the electromagnetic energy harvester (EMH), with maximum power of 35.12 mW and 0.062 mW, respectively, at a wave frequency of 0.6 Hz. Demonstrating the ability to power devices such as temperature and humidity sensors and LEDs, the PEWEH confirms its potential for providing sustainable power in marine environments, highlighting its innovative contribution to the field of wave energy harvesting.