Adaptive synchronized switch harvesting: A new piezoelectric energy harvesting scheme for wideband vibrations

•The paper presents a new energy harvesting electrical scheme to enhance power generation when the excitation frequency has more than one significant frequency component. In the original ESSH approach, the switching occurs at every extremum. When the excitation frequency has more than one frequency component, it results in the power harvesting circuit being optimized for the highest significant frequency component. Since in many cases the lowest mode with the lowest frequency carries the largest amount of energy this mistuning is undesirable. In the new approach the switching only occurs near the global extremum, which corresponds to the fundamental mode. In the paper, theoretical and experimental results demonstrate the new approach enhances the power harvesting in case of multi frequency vibrations.•A self-powered circuit which implements the technique (ASSH) is proposed, which validates that the new technique can be self-powered. Compared with other self-powered circuits, power dissipation of the proposed circuit is relatively high (about 328.8 μW). Besides, the self-powered energy harvesting circuit is complex, which needs an additional piezoelement and a microcontroller. However, it brings the flexibility of application and validates the feasibility of self-powered operation and theoretical results.

This paper proposes a new energy harvesting architecture that optimizes the energy conversion under broadband vibrations, which is called adaptive synchronized switch harvesting (ASSH) technique. This technique is derived from the enhanced synchronized switch harvesting (ESSH) technique and based on a new and effective switch control law, which can prevent the switch in energy transferring circuit from over-frequent on-and-off and accordingly enhance the extracted power under multimode vibration. Compared with the ESSH technique, theoretical and experimental results demonstrate the new technique can improve electromechanical conversion efficiency when the piezoelectric energy harvester is excited under two-mode vibration, especially in the case of higher vibration amplitude of the second mode. The extracted power with the new technique is more than three times the ESSH technique in the case of the exciting signal of amplitude ratio (3:6). Furthermore, a self-powered circuit which implements the technique (ASSH) is proposed, which validates that the new technique can be truly self-powered, thus addressing the issue of harvesting environmental energy by autonomous devices.