A tapped-inductor buck-boost converter for a dielectric electroactive polymer generator

Energy harvesting applications based on Dielectric ElectroActive Polymer (DEAP) generators have been in the spotlight in recent years after the latter ones' documented advantages against competing electromagnetic and field-activated technologies. Yet, the need for bidirectional energy flow under high step-up and high step-down voltage conversion ratios, accompanied by low-average but relatively high-peak currents, imposes great challenges on the design of the employed power electronic converter. In addition, the effective operational range of the converter is usually limited by the lack of commercially-available, high-efficient, high-voltage, low-power semiconductor devices. In this paper, a high-efficient bidirectional tapped-inductor buck-boost converter, addressing high step-up and high step-down voltage conversion ratios, is proposed for energy harvesting applications based on DEAP generators. The high-side switch of the converter is replaced by a string of three non-matched, non-thermally-coupled, off-the-shelf MOSFETs, extending its effective operational range. Experiments conducted on a standalone DEAP generator validate the applicability of the proposed converter by demonstrating energy harvesting of 0.42 J, at 0.75 Hz and 60 % delta-strain, characterized by a world-first; energy density equal to 2 J per kg of active material.