Theoretical, numerical, and experimental analysis of a broadband and high-capability graded E-shaped piezoelectric energy harvester array under various vibrations

Abstract

Harvesting energy from the environment to energize IoT nodes is a contemporary study focal point. Contemporary research fails to achieve wideband and high-efficiency energy harvesting concurrently, and the majority of studies neglect the stochastic characteristics of ambient vibrations, hence hindering the practical application of energy harvesters. We propose a graded E-shaped piezoelectric energy harvester array (GEEHA) to tackle this issue. In the theoretical part, the average voltage theory of 1-DOF piezoelectric energy harvester (PEH) excited by random vibration is extended to encompass 2-DOF E-shaped PEH, to guide the design of GEEHA. The simulation part examined the energy harvesting and storage capabilities of the GEEHA interfaced with the standard energy harvesting (SEH) circuit and self-powered synchronized switch harvesting on inductor (SP-SSHI) circuit under diverse vibrational conditions. Finally, all the results were validated by experiments. Studies demonstrate that the designed GEEHA achieves high power output across multiple discrete frequency bands within the range of 30–120 Hz, with a maximum output power exceeding 20 mW. And it was found that, the energy output performance of the series-connected PEH array surpasses that of the parallel circuit. For the energy storage capacity of circuits, under harmonic and Gaussian white vibrations, the energy storage capability of SP-SSHI circuit was around 4–8 times that of the SEH circuit. Nevertheless, under bridge vibration, the SP-SSHI circuit did not yield a significant advantage. Ultimately, the GEEHA was employed to power temperature and acceleration sensors. Activation of the wireless sensor nodes was successfully achieved under harmonic vibration, Gaussian white noise excitation, and measured bridge vibration, with activation periods of 19 s, 52.5 s, and 24 s, respectively. Overall, our research has achieved broadband and high-capacity energy harvesting and storage, facilitating the enhancement of green energy supply for IoT nodes.