Bae Sungryong, Kim Pilkee
Department of Fire Protection and Disaster Management, Chosun University, 309 Pilmun-daero, Dong-gu, Gwangju 61452, Korea.
School of Mechanical Design Engineering, College of Engineering, Jeonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896, Korea.
Sensors (Basel). 2021 Feb 22;21(4):1505. doi: 10.3390/s21041505.
In this study, a semi-analytic approach to optimizing the external load resistance of a bi-stable electromagnetic energy harvester is presented based on the harmonic balance method. The harmonic balance analyses for the primary harmonic (period-1) and two subharmonic (period-3 and 5) interwell motions of the energy harvester are performed with the Fourier series solutions of the individual motions determined by spectral analyses. For each motion, an optimization problem for maximizing the output power of the energy harvester is formulated based on the harmonic balance solutions and then solved to estimate the optimal external load resistance. The results of a parametric study show that the optimal load resistance significantly depends on the inductive reactance and internal resistance of a solenoid coil--the higher the oscillation frequency of an interwell motion (or the larger the inductance of the coil) is, the larger the optimal load resistance. In particular, when the frequency of the ambient vibration source is relatively high, the non-linear dynamic characteristics of an interwell motion should be considered in the optimization process of the electromagnetic energy harvester. Compared with conventional resistance-matching techniques, the proposed semi-analytic approach could provide a more accurate estimation of the external load resistance.
在本研究中，基于谐波平衡法提出了一种优化双稳态电磁能量采集器外部负载电阻的半解析方法。利用频谱分析确定的各运动的傅里叶级数解，对能量采集器的主谐波（周期-1）和两个次谐波（周期-3和5）阱间运动进行了谐波平衡分析。对于每个运动，基于谐波平衡解建立了一个使能量采集器输出功率最大化的优化问题，然后求解该问题以估计最优外部负载电阻。参数研究结果表明，最优负载电阻显著取决于螺线管线圈的感抗和内阻——阱间运动的振荡频率越高（或线圈的电感越大），最优负载电阻就越大。特别是当环境振动源的频率相对较高时，在电磁能量采集器的优化过程中应考虑阱间运动的非线性动态特性。与传统的电阻匹配技术相比，所提出的半解析方法能够更准确地估计外部负载电阻。
