Research On Structure Improvement And Energy Management Circuit Of Electromagnetic Vibration Energy Harvester

With the rapid development of smart society,wireless sensor networks and low-power electronic devices have been widely used.However,the operation of many devices is accompanied by the major problem of maintenance costs for replacement or rechargeable batteries.Traditional batteries have the disadvantages of low energy density,limited life time and environmental pollution.Therefore,as an alternative power source for these devices,harvesting energy from the ambient energy sources such as wind,wave,vehicles,and human motion et al.has attracted considerable research interest.Of these energy sources,ambient vibration energy has become one of the most attractive and frequently studied,because of its easy availability and various conversion methods.In this paper,the structure of electromagnetic vibration energy harvester was improved based on the previous research in our group.The response output characteristics and energy management circuit of the energy harvester were studied.Firstly,the basic theory of electromagnetic power generation was introduced,and a new structure of electromagnetic vibration energy harvester was proposed to make full use of the collision between moving part and fixed elastic membrane.The basic principle of the structure was studied in detail.The diamagnetic force,electromagnetic damping force and air damping force were analyzed,related function expression was deduced,and the key parameters were analyzed using finite element simulation software.Secondly,the piecewise linear dynamic model of the energy harvester was established,the influence of system parameters on the vibration model was studied,and the magnetic flux was simulated.The magnetic flux chain degree was calculated based on the relative position of the induction coils and the floating magnet.MATLAB program was used to solve the induced voltage change curve with time,so as to calculate the induced voltage.The establishment and solution of the theoretical model of electromagnetic vibration energy harvester based on piecewise linearity could realize the research on the influence of different parameters on the performance of the harvester.Thirdly,a suitable energy management circuit was designed,and common boost circuits such as Boost boost,charge pump boost,and voltage doubler rectifier circuits were compared.Their advantages,disadvantages,and application range were comprehensively analyzed,and a twelve-stage voltage doubler rectifier circuit was used.The rectifier circuit was simulated and related parameters were optimized.The effect of different external loads on the voltage doubler rectifier circuit was also studied.Through this circuit simulation,the output AC voltage at the millivolt level could be effectively converted into a DC voltage of volt level to power the microelectronic device.Finally,the vibration energy harvester was tested experimentally,and the output characteristics of the energy harvester were studied.Firstly,an experimental prototype was made,and then an experimental platform was built.The shaker was controlled by a computer to give the energy harvester external excitation under different conditions.We used an oscilloscope to collect the output signals,and then performed data processing and analysis.In the course of the experiment,the curves of the output voltage and output power of the energy harvester as a function of frequency under different vibration amplitudes,different excitation accelerations,and different elastic membrane stiffness conditions were tested.At the same time,the experimental results were compared with the theoretical output characteristics to verify the correctness of the model results.Finally,an actual application test of the energy harvester was performed,which showed that the energy harvester had certain application value.