Evaluation and Modeling of Power Generator with Bimorph PZT Cantilever

Abstract

Battery, the traditional power source in present wireless remote sensor systems, has large volume and requires large amount of maintenance. Therefore, piezoelectric power generator has been studied for a potential alternative to battery by scavenging or harvesting energy from its operating environment. The efforts for investigating such piezoelectric device have been especially enhanced by the miniaturization requirement and low energy consumption of advanced devices as well as the sufficient vibration energy sources and its high conversion efficiency. To utilize piezoelectric material as energy conversion transducer, the device should be designed to operate with high efficiency and simple configuration. PZT (Lead Zirconium Titanate) is an excellent candidate for energy conversion because of its large piezoelectric constant and coupling coefficient.

In this study, power generators based on bimorph cantilever structure were designed and fabricated using PZT ceramic benders due to accessible large strain or energy. The parameters influencing the output energy of piezoelectric bimorph cantilevers including the dimensions of the cantilever and the proof mass, the loading ways of the proof mass, and the resonant frequency of the cantilever were systematically investigated. The robustness of cantilever structure was also considered for implementing piezoelectric power conversion devices in harsh environments. The final optimal design was realized by considering the balance between the output power and the safety factor through numerical analysis. The energy density generated by the optimized piezoelectric devices was higher than 1 mW at 1-g vibration, which could be enough to operate microsensor systems. To broaden the operation conditions, multiple-resonant frequency device was also explored.