Research On Frequency-tuning Synchronous Charge Extraction Circuit For Piezoelectric Vibration Energy Harvesting

Drived by the rapid development of low-power electronic equipment technology,the pursuit of intelligence in various fields is pushed to a climax.With the emergence of highly integrated and miniaturized electronic devices,the disadvantages of traditional electrochemical cells are gradually exposed.Energy harvesting technology,which converts energy from the environment into electricity using specific materials or transducers,has received a lot of attention for its ability to power electronic devices,such as wireless sensor nodes,without the use of traditional batteries.Vibration energy has become a research hotspot in energy acquisition technology because of its high energy density and wide distribution.In order to harvest the vibration energy in the environment as much as possible,many scholars improve the frequency bandwidth and output power of the energy harvessting device from the mechanical part and the circuit part respectively.In this paper,the interface circuit is studied for harvesting energy.Two parameter tuning strategy is introduced into the optimized synchronous charge extraction circuit(OSECE),and the optimized frequency-tuning synchronous charge extraction circuit(FT-OSECE)is proposed.Based on this,a series of researches are carried out,mainly including the following contents:(1)This article first introduces the principle of piezoelectric transduction mechanism,then electromechanical coupling system model is established based on the piezoelectric cantilever generator,the optimal principle of harvesting energy in ideal case is briefly analyzed.On this basis,the working principle of frequency-tuning synchronous charge extraction circuit(FT-SECE)is introduced and its analytical model has been derived without the consideration of circuit loss.Then,FT-OSECE is proposed by combining the two-parameter tuning strategy in FT-SECE with the OSECE circuit.The difference between FT-OSECE and FT-SECE is analyzed based on the circuit principle of OSECE,and the circuit quality factor to measure the circuit loss is introduced into the analysis model,and a more complete analysis model is established.Then,from the perspective of macroscopic and analytical model,the limitations and the reasons of the single parameter tuning method related to FT-OSECE in frequency tuning and electric damping tuning are analyzed,which reflects the advantage of the FTOSECE method.(2)According to the analysis model,the electromechanical coupling system under FTOSECE is analyzed in detail.Firstly,the variation trend of the electric damping effect and the equivalent stiffness of system are analyzed under the coadjustment of two parameters.Then,in combination with the ideal analysis model in FT-SECE,when the three system parameters changed,including the circuit quality factor,mechanical quality factor,electromechanical coupling coefficient,the relationship between the optimal output power and the corresponding optimal tuning parameters and the excitation frequency,is analyzed under the influence of the circuit loss.Through analysis,the necessity of considering circuit loss in the analysis model is further proved.(3)Piezoelectric cantilever generator and PCB of FT-OSECE circuit were made,and a complete experimental platform was built for experimental verification.Using the FT-OSECE circuit,five circuit experiments were experimented by appropriately setting the range of tuning parameters.The experimental results of the above circuit are compared with the simulation results based on the analysis model,and the good agreement between them verifies the accuracy of the analysis model.At the same time,the comparative analysis of several circuit results also reflects the advantage of FT-OSECE,and it is pointed out that the improvement of circuit quality factor and the increase of electromechanical coupling coefficient will further show the advantage of FT-OSECE in expanding half power bandwidth.(4)Based on FT-OSECE circuit,the architecture of energy autonomous adaptive parameter tuning system is established,and the design ideas for energy management unit and control unit in the architecture are provided.From the aspects of the widely distributed sensors on the vehicle,the urgency of the innovation of power supply mode and the abundant vibration energy,the FT-OSECE dose have application potential in the vehicle.