Piezoelectric harvesting circuit with extended input voltage range

A high efficiency energy harvester for a piezoelectric generator (PZG) was developed and tested experimentally. The proposed circuit is based on a non linear resonant rectifier that replaces the simple and less efficient diode bridge rectifier. The two stage harvester (rectifier and converter) extends the input voltage range capability and mitigates the dependency of the harvester on PZG output voltage. The second stage of the proposed circuit includes a low loss converter that stabilizes the output voltage. The paper presents a comparison and evaluation of two interface schemes connected to a step-down converter. One is based on a simple diode rectifier front end and the other one is the proposed non linear rectifier. It is shown that in a self powered mode, under same acceleration level of 0.38g, the improved harvesting circuit can increase the extracted power by 186% as compared to a conventional bridge rectifier interface. In addition, experimental results show that the proposed circuit can sustain output voltage regulation 3.4 times longer compared to direct connection bridge topology for 1.8mA load step.