一类薄膜结构振动能量采集器的强非线性动力学分析及结构优化设计

The electromagnetic vibration energy harvester (EMH) is one of the most important vibration energy harvesting devices. The procedure to enhance its energy conversing performance requires a deep insight into the resonant frequency and the optimization strategy of the structure parameters. The limitation of bandwidth is the main problem for the linear energy harvester. The limitation of the nonlinear methodology in dealing with the strong perturbation is the main problem for the nonlinear harvester. So, in this proposal, we try to introduce the corresponding strongly nonlinear theory on widening the bandwidth by accurately calculating the resonant frequency, and strengthening the power output by operating structure optimization of a membrane type EMH. Firstly, a continuum model is established according to the membrane large deflection theory to match the strongly nonlinear oscillation characteristics of the oscillator. Meanwhile, the air damping, nonlinear rigidity and magnetic force are concerned as the necessary components to this model. Secondly, the resonance frequency and the steady-state response of the oscillator are calculated by using the new dynamical frequency method to fully concern the strong perturbations embodied in the system. Thirdly, the nonlinear turning mechanism referring to certain physical parameters is investigated through the local and global bifurcation analysis. It helps to broaden the bandwidth and track the varying excitation frequency in operation. The higher-order energy balance method is introduced to improve the accuracy of computation. Fourthly, the Synchronous Magnetic Flux Extraction (SMFE) technique is improved to design the extraction circuit. According to SMFE, the power optimization principle of the nonlinear EMH is achieved, which addresses the key issue for structure optimization and exploits the potentialities of the architecture. Finally, following the theoretical findings and optimization strategies, the EMH experiments are carried out to improve the harvesting performance and verify the parameter turning strategies. Further attentions will be paid to maintain the sequential implement and sustainable development within this architecture.

电磁式振动能量采集器（EMH）是一类重要的振动能量采集装置，发挥其最佳的能量转化效果，有赖于谐振频率的把握以及结构参数的优化。有鉴于线性振子的带宽有限，而强扰动量作用下非线性EMH的研究方法还有待完善，因此本课题以一类薄膜结构EMH为对象开展研究工作。通过建立相应的强非线性理论体系，准确把握强扰动因素对于谐振频率的影响，拓展频带宽度；开展结构优化，提高输出功率。内容包括：考虑空气阻尼、非线性刚度、磁场力等因素，建立非线性振子的连续体模型；提出研究薄膜振子大幅强非线性振动特性的动态频率方法，充分考虑系统中非线性因素对于谐振频率的影响；发展高阶能量平衡法，应对不同激励形式开展非线性理论分析，探索拓展频带宽度、跟踪外界频率变化所需的参数调节机制；改进磁通量同步提取技术，形成非线性EMH的整体参数优化准则，发挥采集器的结构潜能；通过理论与实验相结合的形式，验证设计思路与研究方法的可行性。

近年来，以便携式通信系统、无线传感器网络为代表的低功耗电子技术取得了长足的发展，并在人们的日常生产活动中发挥着日益重要的作用。与此同时，考虑到很多无线传感器都工作在传统电力网络不能直接供电的区域，而采用电池供电又无法实现“永久化”的长效运行模式，这就导致供电系统的局限成为制约这些设备发展的瓶颈。因此，本课题主要关注工程问题是从环境中高效地获取能量，为潜在无线传感器和低功耗电子设备提供可靠、安全且免维护的电力来源。按照计划，本课题以一类薄膜结构电磁式振动能量采集器（EMH）为背景，围绕上述工程问题演化而来的两点科学问题，即：如何采用有效非线性手段增大采集器工作带宽，如何实现整体输出功率的参数优化，开展研究工作，主要涉及：以课题组提出的动态频率为基础，建立了一种研究复杂强非线性振动问题的理论体系，涵盖了渐近解计算，多稳态全局动力学分析，输出功率优化等主要环节，研究表明该方法具有计算流程简单，分析精度高，实用性强，易于实现程序化等特点；进行了完善的非线性理论分析，着重考察了主要结构参数对于谐振频率、输出功率的影响；结合磁通量同步提取技术（SMFE）与等价线性化观点，探索最大输出功率的优化准则，确定提高能量转化效率的可行性措施，从全新的视角解决了非线性系统结构参数优化困难的主要问题。除此之外，本课题还拓展了采集器结构的结构样式，采用了包括碰撞、分段线性在内的多样化非线性手段增加带宽，引入了数据驱动的建模方法并结合非线性Galerkin方法高精度获取非线性系统方程，并实现了EMH整体建模、分析、优化过程的Mathematica程序化，开发了具有自主知识产权的车载自供电温度传感系统。本课题为EMH提供了可靠的研究手段，形成了可行的优化思路与实用的发展方向。