Self-Contained Resonant Rectifier for Piezoelectric Sources Under Variable Mechanical Excitation

Abstract

A rectification scheme is proposed for increasing the available output power of electrical generators that have a high output capacitance. The proposed rectifier could be useful in increasing the output power of piezoelectric generators (PZG) that convert mechanical vibrations into electrical power. The improvement is achieved by a resonant circuit that self commutates the voltage across the output terminals of the PZG and thereby eliminates the shunting of the output current by the output capacitor. A low-consumption circuit synchronously controls the operation of the resonant rectifier by detecting voltage transitions across the generator. The presented resonant rectifier was experimentally verified by connecting it to a PZG as well as to a PZG emulator. The results show that, under constant harmonic excitation, the proposed circuit can significantly increase the extracted power by up to 230% as compared to a conventional bridge rectifier. The feasibility of using the proposed topology as a self-powered system driven by variable excitation was investigated experimentally as well. In particular, the system was driven by two types of excitation source: amplitude modulated and frequency modulated. It was found that the proposed circuit increases the extracted power by 160% and 172% for AM and FM excitations, respectively.