Hybrid energy harvesting from mechanical vibrations and magnetic field

Abstract

This letter proposes a hybrid energy harvesting scheme to collect the energy from mechanical vibrations and the magnetic field simultaneously. The structure consists of a magnetostrictive substrate bonded with a piezoelectric sheet. The theoretical modeling and experimental investigations are conducted and their results are in good agreement. The effects of phase differences between the harmonic vibration and the AC magnetic field on the behaviors of the energy harvester are investigated. The open circuit voltages are larger than those from either vibration energy or magnetic energy in most phase values, and the energy capacity is mainly determined by the dominant component. The energy harvesting performances of the Galfenol alloy and the nickel alloy are examined, respectively. The results show that the Galfenol alloy is more sensitive to the AC magnetic field, which can enhance the root mean square of the output voltage. Furthermore, the existence of the bias magnetic field (DC magnetic field) can significantly increase the output voltages of the cantilever. The optimal output power of the hybrid energy harvester can increase to 14.82% and 30.40% when compared with the vibration and magnetic excitations, respectively. These findings demonstrate a feasible energy harvesting idea of taking advantage of the ambient vibration and the magnetic energy simultaneously. This letter presents advancements in improving the energy capacity and the reliability.