Broadband rotational energy harvesting using bistable mechanism and frequency up-conversion

This paper presents the electromechanical dynamics of a broadband rotational piezoelectric energy harvester using bi-stability and frequency up-conversion. Bi-stability is achieved by the repulsive force between the tip magnet on a piezoelectric cantilever and a fixed magnet above the tip magnet. Frequency up-conversion is realized by the plucking force generated between the tip magnet and a rotating driving magnet below the tip magnet. A numerical model based on the distributed-parameter model was built in Matlab/Simulink. The power extraction capability of different modes of oscillation was analyzed theoretically. The keys to maintain harvester operation in high energy orbit (inter-well vibration) were investigated. The rotational piezoelectric energy harvester was implemented experimentally, showing a significant improvement in output power over a wide bandwidth compared to a harvester without bi-stability.