Modeling and experimental investigation of asymmetric distance with magnetic coupling based on galloping piezoelectric energy harvester

This paper presents an asymmetric magnetic coupling piezoelectric energy harvester (PEH) based on galloping to scavenge low-speed wind. The piezoelectric beam of energy harvester undergoes bending and torsional vibration simultaneously due to the eccentric distance. By analyzing the kinetic energy, potential energy, and virtual work of the energy harvesting system, the mathematical model of harvester is constructed and verified by experiments. The optimal external load resistance is confirmed at different eccentric distances and wind speeds by experiments. Compared with traditional galloping piezoelectric energy harvester (GPEH), the asymmetric with magnetically coupling GPEH has a lower threshold wind speed, i.e. 2 m s^-1. And the asymmetric configuration contributes to a lower natural frequency and electromechanical coupling coefficient, which results in a lower power and voltage output. The potential energy of harvesting systems at different distances between two magnets are respectively numerical analyzed in detail. The theoretical results illustrate that the energy harvester operates in monostable and bistable at different magnet distances. And the threshold wind speed of energy harvester increases when the energy harvester works at bistable. According to the above analysis, this work provides a detailed guideline for mathematical modeling and performance improvement of asymmetric PEH based on galloping.