Circuit Development of Piezoelectric Energy Harvesting Device for Recharging Solid-State Batteries

Piezoelectric devices have been widely used as a means of transforming ambient vibrations into electrical energy that can be stored and used to power other devices. This type of power generation devices can provide a convenient alternative to traditional power sources used to operate certain types of sensors/actuators, MEMS devices, and microprocessor units. However, the amount of energy produced by these devices is in many cases far too small to directly power an electrical device. Therefore, much of the research into power harvesting has focused on methods of accumulating the energy until a sufficient amount is present, allowing the intended electronics to be powered.Due to the tiny amount of harvestable power from a single device, it is critical to collect vibration energy efficiently. Many research groups have developed various methods to operate the harvesting devices at their resonant frequencies for maximal amount of energy. Different techniques of conversion circuits are also investigated for efficient transformation from mechanical vibration to electrical energy. However, efforts have not been made to the analysis of array configuration of energy harvesting elements. Poor combination of piezoelectric elements, such as phase difference, cannot guarantee the increasing amount of harvested energy. To realize a piezoelectric energy-harvesting device with higher volume energy density, the energy conversion efficiencies of different array configurations were investigated. In the present study, various combinations of piezoelectric elements were analyzed to achieve higher volume energy density. A charging circuit for solid-state batteries with planned energy harvesting strategy was also proposed. With the planned harvesting strategy, the required charging time can be estimated. Thus, the applicable applications can be clearly identified.In this paper, optimal combination of piezoelectric cantilevers and different modes of charging methods were investigated. The results provide a means of choosing the piezoelectric device to be used and estimate the amount of time required to recharge a specific capacity solid-state battery.Copyright © 2012 by ASME