Comprehensive comparative analysis of piezoelectric energy harvesting circuits for battery charging applications

In this paper, three different ac-dc converter circuits are compared that can be used as energy harvesting circuits from piezoelectric sources, like periodic mechanical vibration of piezo-material cantilever beam, and used to supply voltage to charge battery energy storage devices. The study in particular investigates the effect of introducing the third and fifth harmonics along with the fundamental input on the output voltage, current and power delivered to the load. The model used for the Li-ion battery cell is also included. The comparison is done on an even basis by all circuits being open looped and having the same input parameters and load characteristics, i.e., battery model, for each circuit. The simulations were conducted using PSIM software implementing the three different energy harvesting mechanism their circuitry. The average load voltage and current was observed and the power delivered also recorded and compared. Simulation results are presented that output voltage is within 3.5 and 4.2 V. The study facilitates in understanding the nature of voltage and current response to the different approaches to the ac-dc conversion circuitry and provides an insight on the regime to store this energy produced by piezoelectricity.