A Dual-Purpose Piezoelectric Multi-Beam Energy Harvesting and Frequency Measurement Device for Rotational Applications

In this paper we describe the development of a novel rotational energy harvesting device for a broad range of rotating frequencies. In addition to harvesting capability, the device can be used to measure the rotating frequency of the equipment being utilized. The device has potential to utilize several piezoelectric beams and corresponding actuating magnets for maximum performance and therefore can generate high power at different rotating frequencies. Thin Lead-Zirconium-Titanate (PZT) piezoelectric cantilever beams were fixed on a stationary wheel. Small magnets were bonded on the tip of the piezoelectric beams. Similar magnets were attached to the rotating pins installed on the moving wheel. The driving magnets attracted the magnets on the cantilever beams when the moving wheel rotated and caused vibration in the cantilever beams. In order to characterize the device, two types of the device layouts including single and double plucking magnets were considered in the tests. The device had room to use up to six plucking magnets and four piezoelectric beams. We tested the harvester at different rotating frequencies, from 180 rpm to 500 rpm and measured voltage outputs as a function of time. We found that the output voltage increased by adding the number of moving magnets and increasing the rotating frequency. In addition, the device was able to accurately measure the rotating frequency of the testing equipment.