磁铁夹持式压电俘能器输出性能分析与试验

Performance analysis and test of a piezoelectric energy harvester based on magnets holding

为满足旋转机械监测系统的自供电需求,针对旋转式压电俘能器存在可靠性低和频带窄的问题,提出一种磁铁夹持式压电俘能器。利用MAPLE仿真软件建立了俘能器动态响应模型,通过仿真分析和试验研究得出了磁铁夹持具有调频的作用。研究结果表明:存在最佳转速使俘能器峰值电压最大,且谐振峰数及最佳转速随动磁铁数增多而减小;随着动磁铁数的增多,激振力的表现形式会由一般周期激励变为简谐激励,最后变为偏置的简谐激励;当动磁铁数为4时,改变中心距L和夹持间距D便可间接改变俘能器系统等效刚度,实现其谐振频率的调节:当L为0,2,4mm时,俘能器出现最大峰值电压所对应的激励频率分别为46.4,38.4,31.2Hz;当D为1,4,7mm时,最大峰值电压所对应的激励频率分别为46.4,38,36Hz,拓宽了俘能器的有效工作频带。此外,在动磁铁数为4,L为0,D为1mm和转速为666r/min时,存在最佳负载400kΩ使俘能器输出功率达到1.3456mW。

To meet the demands of self-powered monitoring system for rotating machines and solve the problems of lower reliability and narrower working frequency band for rotary piezoelectric energy harvesters, a piezoelectric energy harvester(PEH) of rotating magnets excitation based on magnets holding is introduced. The dynamic response model of the harvester is established by the MAPLE simulation software, and through simulation and experiment it is found that the magnets holding has the frequency adjusting effect. The research results show that there is an optimum speed to achieve the maximum peak output voltage, and the number of resonant peaks and the optimal speed decrease with the increase of the number of exciting magnets. The form of the exciting force will change from the pulse excitation to the simple harmonic excitation and then to the forward biased harmonic excitation with the increasing of the number of exciting magnets. When the number of exciting magnets is 4, changing the center distance L and the holding distance D will change the equivalent stiffness of the PEH indirectly and adjust its resonant frequency: when L are 0,2,4 mm, the maximum peak voltage corresponding to the exciting frequency are 46.4,38.4,31.2 Hz, and when D are 1,4,7 mm, the maximum peak voltage corresponding to the exciting frequency are 46.4,38,36 Hz. Clearly, magnets holding can broaden the effective working frequency band. When the number of exciting magnets is 4, L is 0, D is 1 mm and the speed is 666 r/min, there is an optimal load of 400 kΩ such that the output power of PEH is up to a maximum value of about 1.3456 mW.