Loosely power flow control scheme for piezoelectric energy harvesting

Piezoelectric energy harvesting generally employs a maximum power point tracking (MPPT) control scheme in the DC-to-DC converter in order to continuously track to the maximum power point (MPP) voltage of the piezoelectric energy harvester (PEH). Owing to the high power consumption of the MPPT-based control circuit, the efficiency of the converter remains at an essentially low level. Proposed is a loosely power flow (LPF) control scheme to intermittently operate the converter near the MPP voltage of the PEH. Experimental verification on a 22μW PEH prototype finds that the power consumption of the LPF-based control circuit is as low as the quiescent power of the converter and the efficiency of the converter is as high as 56%.