A new synchronized switching harvesting scheme employing current doubler rectifier

Piezoelectric energy harvesting from ambient mechanical vibrations has been of significant interest over the last years for powering electronic devices. It has been proved that the harvested energy can be greatly improved by applying non-linear treatments of the piezoelectric voltage called the SSHI (synchronized switch harvesting on inductor) circuit. However, the electric energy accumulated on the inductor in the SSHI interface has not been considered yet, which limits the effectiveness of energy harvester. The purpose of this paper is to present a new hybrid scheme that combines the classical SSHI interface employing the current doubler rectifier (CDR) circuit to get more energy from the inductor. Although the scheme relies on the existed Synchronized Switch Harvesting interface, the switching operation of the proposed scheme which provides four energy extraction cycles per vibration period is quite different from that of the SSHI. It is shown both theoretically and experimentally that the harvested power can be significantly increased with such a circuit. In particular, the proposed SSHI–CDR interface allows a power gain of over 1.8 compared to the classical series SSHI interface, and a power gain of over 8.8 compared to the standard interface, including a diode rectifier bridge and a filter capacitor.