On Development of a Fully Operative Piezoelectric-Based Vibration Energy Harvesting System

A new generation of sensor and actuator, e.g. for SHM application, is forcing us to look for new energy sources which would be used instead of battery & classical power generators. Future of (aerospace) industry goes toward sensors and/or actuators embedded, permanently bonded or even inter-layered into main structures. Supply of these items with the needed power is still an opened issue. Classical power supply (battery and generators) have several drawbacks like the short life of batteries with related maintenance and substitution, making impossible the embedding and inter-layering of new concepts sensors/actuators due to the lack of accessibility. Generators have similar drawbacks with the additional problem of power transferring and consequent complexity and weight penalization. Obtain energy from no conventional source (Energy Harvesting - EH) will become more and more important over the years. In airplanes (like in bridges, building, land vehicles ... ) a constant and unused source is the mechanical energy lost in vibration that can be converted in exploitable. Harvest energy from structural vibrations offers several advantages. Firstly, the proposed EH system have extremely low weight and small dimensions, as a result energy can be generated in situ, without need for power transfer from central generator to peripheral sensor/actuators, minimizing thus the cabling. Secondly the system can be mounted everywhere, is extremely flexible, highly configurable. The only requirement is a vibration level high enough to activate the energy harvesting. Thirdly, the system is piezoelectric-based, highly compatible with a large family of (aeronautics) sensors/actuators that share the same technology. Potentially the proposed energy harvesting system can be integrated directly in sensors/actuators system, maybe sharing the same piezoelectric elements that can recollect the energy that they itself needs. Finally the system is maintenance-free; it can be surface mounted, embedded or inter-layered exactly in the same way as the powering sensor/actuator. Other potential advantages will be the additional damping provided to vibrating structure. In test campaign newest piezoelectric patch was used as voltage generator due to its flexibility and low thickness. An electronic device based on commercial integrated circuits is used to rectify voltage and store energy in condensers for future utilizations. Many parameters must be considered during optimization, here the most important ones will be discussed. In order to evaluate performance and identify possible bottlenecks, full system and component efficiencies were measured. This paper: presents the developing of a real, lightweight, compact and optimized piezoelectric-based energy harvesting system; proves that piezoelectric patches are suitable for energy harvesting applications; present a real, optimized and easily realizable electronic device which can be used in conjunction with other power sources; presents an innovative experimental method to measure patch efficiency.