Adaptive piezoelectric energy harvesting circuit for wireless, remote power supply

This paper describes an approach to harvesting electrical energy from a mechanically excited piezoelectric element. A vibrating piezoelectric device differs from a typical electrical power source in that it has significant internal impedance limiting available power output, and may be driven by mechanical vibrations of varying amplitude. The energy harvesting approach is loosely based on the fundamental electrical engineering concept of optimal loading. The harvesting circuit consists of an AC-DC rectifier with an output capacitor, an electrochemical battery, and a switch-mode DC-DC converter that controls the energy flow into the battery. An adaptive control technique is used to continuously maximize the power transfer into the battery. Experimental results reveal that use of the adaptive DC-DC converter increases power transfer by over 400% as compared to when the DC-DC converter is not used.