Efficacious piezoelectric energy harvesting, including storage from low-frequency non-periodic bridge vibrations

Although piezoelectric energy harvesting (PEH) from structural vibrations is well-recognized as a viable para­digm for renewable power generation in the micro- to milliwatt range, most real-life structures, such as bridges, are characterized by low-frequency erratic vibrations, which tend to diminish their practical utility for PEH. This is because the interface circuits invol­ved in rectification and storage tend to lose their efficiency on account of low frequencies and the erratic nature of real-life structural vibrations. This study proposes a fine-tuned D1000 bridge rectifier circuit to circumvent the above problem, culminating in a successful proof-of-concept demonstration of PEH and subsequent storage in Ni–MH rechargeable batteries from real-life bridge vibrations. The unique feature of this experimental study entails successfully utilizing simple-type piezo elements directly bonded to the host structure and operating in the d31 mode. Additionally, piezo elements bonded to a secondary cantilever structure (acting as a parasite to the main structure) are studied for comparison. Here we present a laboratory-based experimental study of a bridge rectifier circuit for charging a battery from the energy harvested using piezoelectric elements. Results show that it is feasible to charge a battery under a low-frequency and low-voltage scenario (Voc = 1 V at 5 Hz) employing the proposed D1000 rectifier circuit. We also present a field evaluation of the fine-tuned circuit on vibrations of a real-life flyover. Storage of energy in the capacitor as well as battery has been successfully realized in a realistic environment, achieving a power of 0.27 mW. This study represents successfully increasing the technology readiness level of PEH from 4 to 7 from structural vibrations.