Magnetically Actuated Piezoelectric-Based Rotational Energy Harvester With Enhanced Output in Wide Range of Rotating Speeds

This paper reports the design, fabrication, and performance of a novel rotational energy harvester, utilizing multiple magnetic actuators and piezoelectric beams for the maximum performance in a wide range of rotational speeds. The harvester can be used in different rotational applications with low or high rotational speed and produce high output. Thin lead-zirconium-titanate (PZT) piezoelectric beams were fixed on the axis of a nonmoving wheel. One end of the beams was fixed to the center axis of the stationary wheel, while the other end hung free. Small magnets were bonded on each of the piezoelectric beams' free ends and on a concentric wheel, fixed to a working shaft. As the working shaft drove the dynamic wheel, the magnets on the moving surface attracted the magnets on the piezoelectric beams, causing the beams to be plucked into vibration as the magnets passed by one another. The device was tested at six different rotational speeds from 180 to 500 r/min, with two different layouts, single and double plucking magnets. There will be potentials to increase up to six plucking magnets and four piezoelectric beams in this design for an increased performance. Voltage output versus time graphs were analyzed for each speed and setup. It was determined that increasing the number of plucking magnets and rotational speed was the most effective ways to increase the beam vibration and maximize the energy harvester's performance. This is the most effective approach to increase the performance of the energy harvester in the applications that require lower speeds. The least effective case was the low speed, single magnet design, where the beam vibrated little and approximately half of the energy harvester's time was idle time, minimizing the power harvested.