采用Helmholtz共鸣器与悬臂梁压电换能器的声能采集器研究

Study on acoustic energy harvester using a Helmholtz resonator and a cantilever piezoelectric transducer

针对环境中广泛存在的声能,提出了一种采用Helmholtz共鸣器和悬臂梁压电换能器的声能采集器。Helmholtz共鸣器对入射声压进行放大,放大后的声压引起共鸣器弹性薄壁振动,薄壁的振动传递到压电换能器产生电能输出。建立了带弹性壁的立方形共鸣器的等效集中参数理论模型,并与压电换能器的机电特性结合,分析了声能采集器的声-机-电转换原理,研究了声压、声波频率和负载阻抗对输出功率的影响,研究结果为此类声能采集器的优化设计及工程应用提供了一种可行的方法。实验中,声源通过声波导管输出声能,当共鸣器管口处的声压级为94 dB时,系统实测最大输出功率达240μW。该采集器不仅可作为声能自供能采集器,还可在较远距离为低能耗电子装置进行有源声供能。

Aiming at harvesting acoustic energy widely distributed in the environment, an acoustic energy harvester using a Helmholtz resonator （HR） and a cantilever piezoelectric transducer is proposed. The HR amplifies incident sound pressure, the interior sound pressure of HR causes the elastic thin wall to vibrate, the piezoelectric transducer converts vibrational energy to electric energy. A theoretical model of the cubical HR with the elastic wall based on equivalent lumped parameter assumption is developed. The acoustic-mechano-electric performance of the harvester is analyzed by combining the lumped parameter model with the electromechanical characteristics of the piezoelectric transducer, and the influences of sound pressure, acoustic frequencies and load impedances on the output power are investigated. The study results provide a method for optimization design and engineering applications of such harvesters. In the experiment, a sound source emits acoustic energy through an acoustic waveguide, and a prototype produces maximum output power of 240/~W for a sound pressure level of the entrance of the HR at 94 dB. This harvester can be applied in not only acoustic self-powered devices but also the active energy supply for low-power electronic devices at long distance.