腔式压电气流发电机结构与性能研究

摘要

为满足农业物联网实时状态监测系统的供电需求,提出了一种腔式压电气流发电机,并从理论和试验两方面进行了研究,获得了激励参数(激励距离、气流压力)及结构参数(主副腔长度及直径)对输出电压的影响规律.研究结果表明,其他参数确定时,存在最佳距离df*、最佳主腔长度lc*及最佳腔盖孔径dr*,使发电机输出电压最大,且df*、lc*、dr*及其所对应的最大电压均随气流压力增加而增加.此外,气流压力较低时存在最佳副腔长度lr*,使输出电压最大,且lr*随气流压力增加而减小,所对应的最大电压随气流压力增加而增加;相反,气流压力较高时,输出电压随副腔长度减小而增加,无副腔时输出电压最大.故实际测试中可根据气流压力确定腔体尺度.试验测得发电机最大功率为2.61 mW.%To meet the energy demand of micro-type sensor and real-time condition monitoring system,and reduce the pollution of chemical batteries to water and soil,a piezoelectric airflow energy harvester based on resonant cavity was presented.In order to obtain the vibration state of the fluid in the energy harvester and the deformation characteristics of the piezoelectric transducer when the structure was different,the energy harvesters with different structures were established and simulated by COMSOL,the results showed that the structure of the generator had great influence on the deformation and vibration frequency of the piezoelectric transducer.The influential factors on the harvester properties were analyzed and proof experiments were carried out,the effects of excitation parameters (excitation distance and air pressure) and structural parameters (the length and diameter of the cavity and neck) on the output voltage were obtained.Under other given parameters,there were optimal excitation distance (df*),length of cavity (lc*) and diameter of hole (dr*) for the voltage to achieve their peaks,besides,lf*/lc* /dr* and the corresponding maximum voltage were increased with the increase of air pressure.In addition,when air pressure was low,there was optimal length of neck to maximize the output voltage,lr* also was decreased with the increase of the air pressure and the corresponding maximum voltage was increased with the increase of the air pressure;on the contrary,when air pressure was high,the output voltage was the maximum without neck,and it was increased with the decrease of length of neck.As a result,the structure and scale of the cavity should be determined according to the air pressure.Under other given parameters,the optimum external resistance (R*) was increased with the increase of the length of neck (lr),and the output power (Pg) was decreased with the increase of the length of neck (lr),the maximum power of the energy harvester was 2.61 mW in the process of experiment.