A Multistep Charge Extractions and Voltage Bias-Flip (MCEBF) Interface Circuit for Piezoelectric Energy Harvesting Enhancement

In piezoelectric energy harvesting (PEH), interface circuits using synchronous switch actions, including synchronized charge extraction (CE) and/or bias-flip (BF), can achieve much higher energy harvesting (EH) capability, compared with the standard energy harvesting (SEH) bridge rectifier. In this article, a multistep charge extraction and voltage bias-flip (MCEBF) interface circuit is proposed to further enhance the harvesting capability under weakly coupling conditions. The EH enhancement is realized by reducing the dissipation in CE with multiple CE actions and simultaneously enlarging the extracted energy with a BF action. MCEBF can also generate positive and negative voltage rails via buck-boost topology to supply power for double-rail devices. The optimal control method of MCEBF is theoretically derived. In our experiment, under constant deflection excitation, the best MCEBF case offers 487%, 95%, and 49% more harvested power, compared with SEH, synchronous electric charge extraction (SECE), and parallel synchronized switch harvesting on inductor (P-SSHI) interface circuits, respectively. MCEBF also keeps the benefit of load independence as SECE does under weakly coupling conditions.