压电能量俘获结构及其升频转换技术的发展现状

压电材料作为一种良好的机电换能元件，具有体积小、成本低、工作性能可靠等优势，但如何设计压电振子高效地俘获环境振动能，仍是本领域的关键技术难题。以定频式、调频式和宽频式三类典型压电振子为代表的结构共振频率匹配设计能部分解决上述难题，但面向环境低频、超低频振动能俘获，上述振子仍面临输出功率低、可靠性差等问题，途径之一是通过机械式升频转换技术将低频激励转换成压电振子的高频振荡，同时突破超低频压电元件功率密度低的限制。几类机械式升频转换技术被区分并简要介绍，重点阐述一种借助非线性系统内共振现象实现的机械升频转换方法。内共振升频技术具有激励加速度阈值低、升频转化能量损失少等优势，进一步拓宽压电振子领域内的机械式升频转换研究。

Recent Development of Piezoelectric Energy Harvesting Structures and the Technology of Frequency Up-converting Oscillators

Piezoelectric material is a kind of excellent electromechanical conversion element, has the advantages of small volume, low cost, reliability and so on. But how to design piezoelectric oscillators and efficiently scavenge ambient vibration energy, is still a key technical problem needed to be solved in the corresponding field. Three kinds of typical piezoelectric oscillators based on the resonant frequency matching strategy, represented by constant resonant frequency, resonant frequency tuning and wideband operating frequency structures, are the partial solution to the problem mentioned above. However, the problems such as the low output power and the reliability of oscillating structures are still existing, while harvesting the ambient low or ultra-low frequency vibration energy. To up-convert the excitation frequency into high oscillation frequency of piezoelectric structures through mechanical frequency up-conversion technology, is a reasonable approach and can break through the low power density limitation of piezoelectric elements under the condition of ultra-low frequency. Several kinds of mechanical frequency up-conversion techniques are distinguished and introduced, especially for an internal resonance based frequency up-conversion approach in nonlinear vibration systems. Such approach has the advantages of low threshold of excited acceleration, less energy losses during the frequency conversion stage, etc., broadening the mechanical frequency up-conversion research in the field of piezoelectric oscillators.