Piezoelectric Energy Harvesting Method Based On Synergistic Effect

Wireless sensor nodes play an important role in monitoring systems for various industrial equipment,and energy supply is a key technology that directly determines the lifespan of wireless sensor networks.Traditional battery-powered methods face issues such as short lifespan and difficult periodic replacement.With the development of energy harvesting technology,obtaining energy from the environment has become a new way to continuously supply power to wireless sensor nodes.Piezoelectric vibration energy harvesting methods,including simple structure,high conversion efficiency,and high output voltage,have been widely used in node power supply.However,traditional cantilever beam piezoelectric energy harvesting methods face the problem of narrow frequency band,and are unable to adapt to the random,discrete and wide-band vibration frequencies in the environment.Therefore,broadening the effective bandwidth of cantilever beam piezoelectric energy harvesting methods is the key to improving their power generation performance.In this thesis,we analyzed the cantilever beam piezoelectric energy harvesting method under magnetic synergy.Based on traditional array-type piezoelectric energy harvesting method,we introduced magnetic interaction force and proposed a multi-stable state piezoelectric energy harvesting method based on the synergy effect.We studied the spatial potential energy configuration characteristics and multi-stable state properties of the multi-beam array under the synergy effect,and explored the influence of the collaborative multi-stable state effect on power generation performance.The main research contents of this thesis are as follows.(1)Modeling and analysis of magnetically synergistic bistable cantilever beam energy harvesting method.Firstly,based on the magnetic dipole theory,we established the structural model of the magnetic action single degree of freedom system and derived the potential energy function model under magnetic action.Then,we constructed the structural model of the magnetic synergy two-degree-of-freedom bistable system,studied the dynamic model and potential energy field model of the magnetic synergy two-degree-of-freedom system,and explored the influence of magnetic moment variation and gravity introduction on the magnetic synergy system.The results show that increasing the magnetic force will lead to an increase in the frequency difference of the first two orders of the two-degree-of-freedom system,an increase in the distance between stable points,and a more obvious bistable characteristic.Without considering the effect of gravity,the potential energy field presents obvious symmetry.With the introduction of gravity,the potential energy field undergoes deformation,and there is a significant potential energy difference between stable points.(2)Modeling and analysis of multi-beam synergistic poly-stable method.Firstly,we established the structural model of the multi-beam synergistic poly-stable method and derived the potential energy function of the synergy multi-stable method.Then,we proposed a numerical solution method for calculating the stable point positions of the multi-beam synergy multi-stable method.Finally,we introduced the spatial distribution potential energy configuration into the study of multi-stable characteristics of the three-beam synergy,and analyzed the influence of parameter changes in the three-beam synergy on the multi-stable characteristics.The results show that in the three-beam synergy array,the stiffness of the cantilever beam and the magnetic moment of the permanent magnet will cause the expansion or contraction of the equipotential surface,resulting in a transition between four stable states and two stable states;while the change in end mass and arrangement order will cause deformation of the equipotential surface,resulting in three stable states and single stable state.(3)Study on power generation performance of synergetic poly-stable method in three beams.Firstly,we designed an experimental testing platform for the three-beam synergy array to test and record the multi-beam vibration displacement and open-circuit voltage.Then,we analyzed the power generation performance of the three-beam two-stable array and the three-beam four-stable array,studied the dynamic response characteristics and energy output characteristics of the multi-beam synergy arrays with different numbers of stable states,and compared the power generation performance of the synergy arrays with that of non-synergy arrays.Finally,we analyzed the influence of different parameters and combinations on the power generation performance of the three-beam synergy array under the same working frequency band,and optimized the parameters of the three-beam synergy array.The results show that compared with the non-synergy three-beam array,the proposed magnetic synergy three-beam array performs better in frequency band and power generation performance.Under the same working frequency band,the power generation performance of the variable-mass three-beam array is better than that of the variable-stiffness three-beam array.Among the different arrangement combinations of the three-beam synergy array,the power generation performance is optimal when the three beams are arranged in order according to their natural frequencies.(4)Energy Management Circuit Design and Performance Analysis.Firstly,we analyzed the power consumption requirements of the sensor nodes and the energy output characteristics of the multi-stable synergy array.Then,we designed an energy management circuit based on the LCT3331 chip and its PCB,and produced a material object of energy management circuit.Finally,we analyzed the performance of the energy management circuit using the multi-stable synergy array as input.The research shows that under random excitation(frequency 10-20Hz),the three-beam synergy array can provide continuous and stable energy supply to meet the usage requirements.This thesis includes 69 figures,14 tables,and 88 references.