Modeling and Experimental Investigation of a Periodically Excited Hybrid Energy-Harvesting Generator

In this article the modeling of a broadband energy harvester utilizing piezoelectric and electromagnetic effects for rotational applications is presented. The hybrid energy harvester consists of a one-side-clamped piezoelectric bimorph with a solenoid on the free end and is excited periodically but non-harmonically by magnets that are fixed on a rotating object. To estimate and describe the performance of the energy harvester concept a linear semi-analytical model for the bimorph and the solenoid is developed and then enhanced for non-harmonic system oscillations by decomposing them into their harmonic components. A comparison between the calculated and measurement signals of a prototype device shows great conformity. According to model-based and experimental analysis, the hybrid system has good broadband behavior regarding electric power output. That aspect makes the device a perfect energy-harvesting system for application with highly fluctuating revolution speeds like miniature wind turbines.