Simulation-based design and optimization of piezoelectric energy harvesting systems - from mechanical excitation to usable electrical energy

Piezoelectric energy harvesting is one key-technology for the realization of autarchic sensor nodes in mechanically excited environments. The optimization of piezoelectric energy harvesting systems, however, remains a challenging task, since the harvested energy depends on the behavior and interaction of various subsystems. Common approaches focus on optimizing parts of the energy harvesting system, while effects of other parts are simplified or not considered at all. In this contribution, we present a finite element simulation-based design and optimization approach without any phenomenological simplifications. This approach considers the entire piezoelectric energy harvesting system, from mechanical excitation to usable electrical energy. To generate accurate models of such harvesting devices, it is essential to have precise material data of all involved materials. These material parameters are determined through the inverse method, a simulation-based approach for identifying all small signal parameters of piezoelectric materials, as well as the mechanical parameters of the involved passive materials. The set of differential equations, resulting from the spatial discretization of the finite element method, is then reduced and implemented into a Matlab-Simulink model. This makes it possible to implement electric networks and to optimize the entire piezoelectric energy harvesting system.