A SECPE Circuit Based on Optimal Flipping Control for Weakly-Coupled Piezoelectric Energy Harvesters

Abstract

Piezoelectric energy (PE) harvesters can harvest vibration energy and convert it into electrical energy, which provides a promising solution to supply sustainable power for wireless sensor networks (WSN) applications. Synchronous electric charge extraction (SECE) technique can optimize the extracted power from a PE harvester regardless of the connected load; however, its performance degrades seriously when the PE harvester is in weakly-coupled ($k^{2}\cdot Q_{m}\lt \lt0.75)$. In this letter, a synchronous electric charge partial extraction (SECPE) circuit is proposed for weakly-coupled piezoelectric energy harvesters. The SECPE circuit can flip the PE voltage to the value that is equal to the load voltage by utilizing the voltage clamping effect of a flyback transformer. It can also adjust the load voltage to the desired value through an optimal voltage flipping controller. The simulation on a weakly-coupled PE harvester shows that the prototyped SECPE circuit can extract a peak power of 243$\mu$W with an open-circuit PE voltage of 3. 5V. Compared with the standard SECE, the output power is increased by 53% under the same conditions. This scheme can contribute to improve the energy extraction from weakly-coupled PE harvesters.