Development of a dynamic model for piezoelectric raindrop energy harvesting

• Main Author: Wong, Voon-Kean
• Published: University of Nottingham 2018
• Subjects: TK7800 Electronics
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.734398

Over the last decade, advancement of microelectronics has triggered a growing interest in ambient energy harvesting. Ambient energy can be found in various forms such as: thermoelectric, acoustic, solar, and mechanical vibrations. Most of the stated ambient energy sources have been thoroughly investigated. One of the relatively unexplored ambient energy sources is raindrop impact energy. Raindrop impact energy harvesting is achieved by converting the strain induced by an impinging raindrop on a piezoelectric beam into usable electrical energy. Most of the conducted research from the literature only considered single droplet impact on a piezoelectric beam. More interestingly, actual field test has yet to be conducted. These are the areas that the research will cover. A commercial piezoelectric beam (Mide-v25w) is utilised for this research. In this work, the piezoelectric beam is modelled as a distributed parameter system. To describe the post impact behaviours and water layer formed on the piezoelectric beam, impact coefficient and added mass coefficient are introduced for respective cases. Excitation models for single droplet, multiple droplet, artificial rain, and actual rain are developed. The models presented here were validated via experimental results. A hybrid bridge rectifier is designed and tested under actual rain. Experiment results showed that the half bridge rectifier is able to produce 95.12 % more energy than the full bridge rectifier during low voltage operation. From the actual rain experiment, the raindrop impact energy harvester was able to produce 1564 µJ energy over a rain period of 3539 s. The maximum instantaneous power generated by the piezoelectric was found to be 3.75 mW. This is higher compared the highest instantaneous power recorded in the literatures, which was 23 µW.