Numerical and experimental study of a novel body-mounted piezoelectric energy harvester based on synchronized multi-magnet excitation

This paper presents results of finite element analysis and testing of a novel frequency up-converting multi-magnet piezoelectric vibration energy harvester, which advantageously exploits multiple magnetic excitation events per single cycle of out-of-plane plucking together with amplification of driving magnet speed in order to provide sufficiently stable generation of nearly constant high average power when subjected to real-life human body movements. It is based on a cantilevered bimorph that is magnetically deflected and released (plucked) by a couple of driving magnets that are accelerated by means of magnets placed on inertial rotor. It was demonstrated that the proposed device operating in a synchronized multi-magnet excitation regime outperforms its conventional single-magnet counterparts, thereby constituting a viable vibration energy harvesting concept that addresses key challenges associated with time-varying ultralow frequency biomechanical excitations.