Structural Design And Experimental Study Of Low Frequency And High Performance Piezoelectric Energy Harvester

With the progress of Micro-Electromechanical System(MEMS)technology and wireless sensor technology,a large number of low-power devices are applied in production.And the piezoelectric energy harvester has been widely studied.The frequency of the common vibration source in human life is low,usually between 20 Hz-200 Hz.For the resonant piezoelectric energy harvester,when its resonant frequency is matched with the frequency of vibration source,the output performance of the device is the best.However,most of the piezoelectric energy harvesters that are studied nowadays often have high frequency,low output power density and poor structural stability,which would limit their application in production.In this paper,the optimization structural design;and fabrication process of low frequency and high performance piezoelectric energy harvester were performed.The main contents of this paper are as following:1.Three kinds of cantilever beam structure piezoelectric energy harvesters based on bonding PZT piezoelectric material with bronze are designed.Meanwhile,the output performance of the devices is simulated to optimize the structural parameters.The phosphorus(or beryllium)bronze is used as supporting layer material of the cantilever beam due to its flexibility.The thickness of composite beam is thin,and the proof mass is added to reduce the resonant frequency of the device.By comparing the resonant frequency,the optimal matching resistance and the output power of two kinds of devices,one is the traditional piezoelectric functional layer,another is the piezoelectric functional layer partially covering cantilever beam structure device.The piezoelectric functional layer partially covering cantilever beam structure device has better performance than fully covering cantilever beam structure.2.The design of a cantilever beam structure piezoelectric energy harvester with a rectangular hole based on the bonding process of silicon chip,phosphor bronze and PZT thick film is proposed.The resonant frequency of this piezoelectric energy harvester is low,and by testing,the first resonant frequency of the device is about 35 Hz,when the excitation acceleration of the device reaches 1.5 g,and the maximum open circuit voltage of the device is 15.7 V,the maximum output power of the device is 216.66 ?W,the current is 170 ?A,the optimal load resistance is 60 k?,and the power density of the device is 1713.58 ?W/cm3.Through the device stability testing,the result shows that the device has good stability.3.The design of a piezoelectric energy harvester with piezoelectric functional layer fully covering cantilever beam structure and based on the bonding bronze and PZT thick film is proposed,which has simple fabrication processes and excellent output performance.It is tested that the resonant frequency of the device is about 171 Hz and the maximum open circuit voltage is 17.8 V under 3 g.The maximum output power of the corresponding device is 196.1 ?W,and the optimum load resistance is 60 k?.It is important that the maximum power density of the device is 18235.26 ?W/cm3,and this performance is very excellent.4.The piezoelectric energy harvester with partially covering piezoelectric functional layer cantilever beam structure is proposed.This device has low frequency,high output performance and good stability.Under 0.7 g,the resonant frequency of the device is about 65 Hz,and the maximum open circuit voltage is 29.1 V.The maximum output power of the device is 79.4 ?W,and the optimal load resistance is 400 k?,the maximum power density of the device arrived at 16533.4 ?W/cm3.Finally,the stability of the device is also tested and the result means that the device has good stability.