Optimal Voltage Profile for MPPT in Piezoelectric Energy Harvesters Loaded by diode bridge rectifiers

This paper is focused on resonant piezoelectric vibration energy harvesters loaded by diode bridge rectifiers. Typically, in such applications the voltage at the output of the rectifier is properly regulated by a DC/DC converter for maximum power point tracking purposes. Resistance emulation and voltage adaptation are the strategies that are usually adopted. In this paper, an optimal shape of the voltage profile at the output port of the rectifier is identified. The proposed voltage profile can lead to the extraction of a higher average power with respect to both resistance emulation and voltage adaptation techniques. In the framework of the fundamental harmonic analysis, the proposed optimal voltage profile allows the emulation, at the harvester terminals, of an ohmic-inductive passive load as required by the maximum power transfer theorem.