Design and analysis of a multi-step piezoelectric energy harvester using buckled beam driven by magnetic excitation

In this paper, a multi-step buckled beam piezoelectric energy harvester driven by magnetic force is proposed. To convert ambient mechanical vibration into electrical energy with increased operational frequency bandwidth and power density, the harvester utilizes a combination of multi-step mechanism and bistable structure. A multi-step mechanism in the form of a magnet array with staggered magnetic poles has been designed for the energy harvesting system to obtain a wide working bandwidth. A buckled beam as a bistable structure enables the harvester to demonstrate a high-voltage output. A theoretical model is developed to characterize the multi-step piezoelectric energy harvester. Both simulations and experiments on the fabricated experimental device are carried out to validate the design and analysis of the multi-step piezoelectric energy harvester. The experimental results indicate that output open circuit voltage of the harvester is 4.4 V. The harvester generates a peak power of 5.0 μW across resistive load of 3.3 MΩ at the frequency of 3.0 Hz. The results show that the device can cause stable output voltage under wideband excitations. Furthermore, under the multi-step mechanism, the magnet array with staggered magnetic poles increases the output voltage of the harvester by 25.0% compared to the unidirectional magnetic pole arrangement.