Analysis and Simulation of Synchronous Electric Charge Partial Extraction Technique for Efficient Piezoelectric Energy Harvesting

Piezoelectric energy harvesting (PEH) is a promising solution to provide life-time energy for ultra-low power electronics such as wireless sensor nodes. Synchronous electric charge extraction (SECE) technique can optimize the extracted power from a PEH device regardless of the connected load; however, its performance degrades seriously when the PEH device is in strongly-coupled. In this paper, a new technique called synchronous electric charge partial extraction (SECPE) is proposed, which is able to address the mentioned problem. It extracts an appropriate portion of piezoelectric energy in a single-time operation by employing the optimal LC oscillation time. The analytical relation between the normalized extracted power and LC oscillation time is derived. Theoretical predictions confirmed by the simulated results show that the optimal duration time is not fixed for different PEH devices. It should be larger than, approximately or smaller than 0.25T(LC) when the PEH device is weakly-coupled, moderately-coupled, or strongly-coupled, respectively. The proposed SECPE technique takes a great advantage, especially, for these PEH devices being weakly-coupled or strongly-coupled and its performance improves by at least 30% compared with the original SECE technique. Meanwhile, its performance does not degrade even the PEH device is in strongly-coupled.