An Efficient Piezoelectric Energy Harvesting Circuit With Series-SSHI Rectifier and FNOV-MPPT Control Technique
S.J. Fang, Huakang Xia, Yinshui Xia, Yidie Ye, Ge Shi, Xiudeng Wang, Zhidong Chen
Abstract
This article presents an efficient piezoelectric (PE) energy harvesting (EH) circuit based on the techniques of series synchronized switch harvesting on inductor (Series-SSHI) and maximum power point tracking (MPPT). The MPPT is achieved using the proposed fractional normal-operation voltage (FNOV) method, which is based on the Series-SSHI operating principle. The FNOV method no longer disconnects the PE harvester from the load circuit to measure its open-circuit (OC) voltage. Instead, it measures the peak PE voltage during the normal Series-SSHI operation to enable the continuous EH process. The FNOV-MPPT circuit is implemented based on a variable width hysteresis controller for saving energy. In addition, the prototyped circuit can achieve the figure of merit factor of 2.68 and the maximum MPPT efficiency of 98.1% with the PE OC voltage ranging from 2 to 5 V. The measurements confirm the validity of the proposed FNOV-MPPT solution for the weakly coupled PE harvesters.