Maximum energy transfer condition for piezoelectric energy harvesters with single pulsed vibration inputs

Abstract

The optimal capacitive load condition is derived for a passive bridge rectifier to harvest the maximum amount of energy when a piezoelectric generator (PG) receives a single vibration pulse (e.g. a button press). When the PG is modelled as a current pulse generator with an internal shunt capacitance (C P), it is shown that an ideal bridge rectifier collects the maximum energy when its output capacitance is set to 3·CP. The impacts of the nonzero turn-on voltage and on-resistance of the diodes are also discussed. The experimental results with a 300 mm2 lead magnesium niobate-lead titanate PG and a Schottky-bridge rectifier with 0.22 V turn-on voltage demonstrate that the maximum energy transfer occurs at a capacitance ratio of 3.3, collecting 117 μJ from a single button press. © The Institution of Engineering and Technology 2014.