Research On Energy Harvesting System Based On A Piezoelectric Cantilever

With the wide application of low-power electronic products such as Micro-Electro-Mechanical-System(MEMS)and wireless sensors,their energy supply problem attracts more and more attentions from researchers.However,many obvious disadvantages such as the limited life span and regular replacement show up when using the traditional chemical batteries.Piezoelectric energy harvesting structure can convert mechanical energy widely existing in environmental vibration into electricity,with advantages of large energy density,structural simplicity and easy-to-miniaturization,which is an effective method to solve this problem.Based on the cantilever piezoelectric structure and considering the coupling of energy harvesting structure and circuit,two piezoelectric energy harvesting circuits,respectively the voltage double circuit based on DC-DC converter and energy harvesting circuit based on LTC3588-1,were designed in this study.Beside the super capacitor was chosen as the energy storage unit,to assemble piezoelectric energy harvesting system.And a series of numerical simulations and experimental researches were carried out on this system.In addition,a wireless sensor is also designed,which can be used to measure the level or inclination angle.And the feasibility of energy supply with this piezoelectric energy harvesting system is verified.The main research contents and results of this work are as follows:1.Based on piezoelectric constitutive equation and Euler-Bernoulli beam theory,a piezoelectric-cantilever structure was design,Then,the model analysis and harmonic response analysis for the piezoelectric cantilever with ANSYS software are implemented;Based on the numerical simulation,equivalent model parameters of RLC for piezoelectric cantilever is presented and verified.2.Based on the RLC electrical equivalent model parameters of the piezoelectric cantilever beam,the simulation and comparison are carried out among the standard interface circuit,the double voltage interface circuit and SSHI interface circuit;On the basis of double voltage interface circuit,Buck DC-DC convert circuit is introduced and designed,and its output characteristic is studied with PSPICE software;The energy harvesting circuit based on LTC3588-1 chip is designed and its circuit performance was simulated in the software as well.3.Connecting the piezoelectric cantilever structure,VD energy harvesting circuit based on DC-DC convertor or the energy harvesting circuit based on LTC3588-1 chip and super-capacitors(3.3V?0.22F)two effective piezoelectric energy harvesting systems are established.Experimental tests are conducted on the output performance base on these two energy harvesting circuits.The results show that the maximum output power of the VD energy harvesting circuit is 1.63mW when the output voltage is 4.8V.The maximum output power of the energy harvesting circuit based on LTC3588-1 chip is 1.98mW when the output voltage is 3.6V.Moreover,the wireless sensor is designed and the feasibility that powering the wireless sensor with the proposed piezoelectric energy harvesting system is verified.