In this study, optimization of the external load resistance of a piezoelectric bistable energy harvester was performed for primary harmonic (period-1T) and subharmonic (period-3T) interwell motions. The analytical expression of the optimal load resistance was derived, based on the spectral analyses of the interwell motions, and evaluated. The analytical results are in excellent agreement with the numerical ones. A parametric study shows that the optimal load resistance depended on the forcing frequency, but not the intensity of the ambient vibration. Additionally, it was found that the optimal resistance for the period-3T interwell motion tended to be approximately three times larger than that for the period-1T interwell motion, which means that the optimal resistance was directly affected by the oscillation frequency (or oscillation period) of the motion rather than the forcing frequency. For broadband energy harvesting applications, the subharmonic interwell motion is also useful, in addition to the primary harmonic interwell motion. In designing such piezoelectric bistable energy harvesters, the frequency dependency of the optimal load resistance should be considered properly depending on ambient vibrations.

中文翻译：

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一次谐波和次谐波行为的宽带双稳态压电能量收集器的负载电阻优化

在这项研究中，针对一次谐波（周期1T）和次谐波（周期3T）井间运动，对压电双稳态能量采集器的外部负载电阻进行了优化。基于井间运动的频谱分析，得出了最佳负载电阻的解析表达式，并对其进行了评估。分析结果与数值结果非常吻合。参数研究表明，最佳负载电阻取决于强制频率，而不取决于环境振动的强度。此外，我们发现，周期为3T的井间运动的最佳阻力往往比周期为1T的井间运动的最佳阻力大三倍，这意味着最佳电阻直接受运动的振荡频率（或振荡周期）的影响，而不是受力频率的影响。对于宽带能量收集应用，除一次谐波井间运动外，次谐波井间运动也很有用。在设计这种压电双稳态能量收集器时，应根据环境振动适当考虑最佳负载电阻的频率依赖性。