Frequency Up-Conversion Piezoelectric-Electromagnetic Hybrid Wave Energy Harvester Based on Magnetic Coupling

A frequency up-conversion piezoelectric–electromagnetic hybrid wave energy harvester (FHWEH) based on magnetic coupling has been proposed. The wave motion is converted into rotation of the rotor by means of a rack and pinion. The excitation frequency can be increased by multiple rotating magnets to approach the cantilever beam intrinsic frequency. The piezoelectric and electromagnetic hybrid mechanism improves the output performance of the FHWEH. The main factors affecting the prototype output have been identified through theoretical modeling and magnetic simulation analysis. The laws governing the influence of magnet spacing, magnet size and magnet quantity on the output performance were investigated experimentally. Under optimal conditions, the maximum voltage of the piezoelectric and electromagnetic parts of the FHWEH were 43.87 V and 1.83 V, respectively, and the maximum power was 20.31 mW and 0.32 mW. The output of the prototype was processed by a rectifier circuit to charge capacitors and power light-emitting diodes (LEDs). The device has been validated for powering miniature sensors and its feasibility in sensor monitoring systems. It provides a new idea and a feasible method for self-powering sensor monitoring systems.