Influence of topology and diode characteristics of AC-DC converters for low power piezoelectric energy harvesting

Abstract Most often, piezoelectric generators are connected to an AC-DC converter, also called rectifier, to obtain a continuous energy which can be regulated and stored. In the case of low power generators, the choice of the rectifier is critical since the losses into this circuit are not negligible and should be as low as possible. In this paper, different topologies of rectifier using different diode references are studied to rectify the output voltage of a piezoelectric generator. We show that the differences between the fullwave rectifier and a voltage doubler are quite small in terms of output power. The main differences are visible on the final voltage value and the optimal load. On the contrary, the choice of diodes is critical, especially the reverse leakage current which must be limited since it largely affects the output power for low power generators. The internal capacitance of the generator also plays an important role since it changes the capability of the generator to provide current. We show that low threshold voltage diodes are more appropriate for generators presenting a high internal capacitance while low leakage current are preferable for generators presenting a low internal capacitance value.