Efforts have been recently devoted to improving the performance of the piezoelectric energy harvesters (PEHs) from the electrical side, in both power harvesting efficiency and operating frequency bandwidth. The frequency-tuning concept for synchronous electric charge extraction (SECE) circuit is a feasible solution by simultaneously adjusting the energy extraction phase and the voltage reversal ratio, especially for highly coupled PEHs. However, in-depth analysis on the influence of the two tuning parameters on the electromechanical system is still not provided. In this paper, the frequency-tuning strategy has been introduced to the optimized SECE (OSECE) circuit in which the two-parameters tuning strategy can be realized more conveniently in comparison with the SECE circuit due to the common ground. Detailed analysis on the frequency-tuning OSECE technique reveals how the energy extraction phase and the voltage reversal ratio affect the system characteristics respectively. Moreover, special consideration is focused on the circuit quality factor which is shown to be a critical factor for determining the tuning parameters. Comparative studies have been performed between the proposed frequency-tuning OSECE (FT-OSECE), the frequency-tuning SECE (FT-SECE), the frequency tunable SECE (only varying the extraction ratio), phase-shift SECE (only varying the extraction phase), conventional SECE and OSECE. Good agreement between the theoretical and experimental results confirms the accuracy of the proposed model and FT-OSECE shows similar performance to FT-SECE with the aforementioned advantages of circuit implementations.

最近致力于从电气方面改善压电能量收集器 (PEH) 的性能，包括功率收集效率和工作频率带宽。同步电荷提取 (SECE) 电路的频率调谐概念是通过同时调整能量提取相位和电压反转比的可行解决方案，特别是对于高度耦合的 PEH。但是，目前还没有对这两个调谐参数对机电系统的影响进行深入分析。本文将频率调谐策略引入到优化的SECE(OSECE)电路中，与SECE电路相比，由于共地，可以更方便地实现双参数调谐策略。对频率调谐 OSECE 技术的详细分析揭示了能量提取相位和电压反转比如何分别影响系统特性。此外，特别考虑的是电路品质因数，它被证明是确定调谐参数的关键因素。已在建议的频率调谐 OSECE (FT-OSECE)、频率调谐 SECE (FT-SECE)、频率可调谐 SECE（仅改变提取比）、相移 SECE（仅改变提取率）之间进行了比较研究阶段）、常规 SECE 和 OSECE。理论和实验结果之间的良好一致性证实了所提出模型的准确性，FT-OSECE 显示出与 FT-SECE 相似的性能，具有上述电路实现的优点。