Study of piezoelectric energy harvesters connected by spring

In recent years, interest in energy harvesting is increasing with the increase of demand of energy and the consideration of the environment. Variety of technologies of energy harvesting have being developed by many researchers. One of them is a technology of electric power generation using the piezoelectric material. Authors have proposed the flexible piezoelectric device (FPED), which consists of a piezoelectric material and an elastic substrate such as rubber, silicon and resin, and have been developing the power generation technology using the FPED, which utilize renewable energy. An issue of the piezoelectric energy harvester and FPED is that the power generation frequency band is narrow. In this paper, a study of FPEDs connected by spring to broaden the power generation frequency band is presented. A forced vibration experiment has been conducted using a power generation system consist of FPEDs connected by spring, and the results show that the maximum power generation and the frequency band are improved by using a spring. A theoretical calculation method is also presented, and its validity is confirmed through comparison of the result by the presented method and the experimental results.