Research On Magnetoelectric Composite Structure And Storage Circuit Applied In Energy Harvesting System

The development of the Internet of Things has brought a most potential market opportunity.In the near future,almost all devicesincluding sensors,low-power electronic modules,wearable electronics and thermostats,will be connected to the Internet.However,how to power these devices is an urgent problem for designers,especially when the equipment is installed in remote locations.Therefore,collecting the energy fromthe environment according to local conditions will be a feasible solution.The characteristics of piezoelectric vibrators and magnetoelectric composites are studied respectively in this thesis with the aim to collectnatural magnetic field energy and vibration energy in the environment.Finally,the collection and storage of micro energy in nature is realized with an energy storage circuit.The main contents of this thesisare as follows:(1)The applications of magnetostrictive effect,piezoelectric effect and magnetoelectric effect were analyzed.The development and application of piezoelectric materials,magnetostrictive materials and magnetoelectric composites were also discussed.Based on the piezoelectric equation and magnetostrictive model equation,the energy acquisition theory of magnetoelectric composite was analyzed.(2)Based on the COMSOL Multiphysics finite element analysis software,the static analysis,modal analysis and harmonic response analysis of piezoelectric vibrator with cantilever beam structurewere carried out.At the same time,the voltage output characteristics of the piezoelectric vibrator were analyzed in detail.And the optimization of the structure was studied,including the shape,size and material of the substrate.It provided a theoretical basis for the structure and size of the piezoelectric vibrator required in the energy harvesting system.(3)The steady state analysis,transient analysis and frequency domain analysis of the laminated magnetoelectric compositeswere carried out using the COMSOL finite element analysis software.The factors affecting the magnetoelectric coefficient of the compositeswere analyzed in details,including the thickness of each layer,the aspect ratio and other parameters of the magnetoelectric composites.The influence of incident angle of magnetic field on the magnetoelectric coefficient of magnetostrictive piezoelectric laminated composite was also studied,which provided a theoretical basis for the application environment of magnetoelectric composite in micro-energy harvesting systems.(4)The magnetostrictive piezoelectric laminated composites were designed and fabricated using rare earth magnetostrictive materials and piezoelectric thin film materials.The magnetoelectric coefficient measurement system was designed by Solidworks3 D drawing software.The magnetoelectric coefficent characteristics of the magnetoelectric composite are testiedand studied.(5)The energy harvesting circuit is designed,which mainly includes: energy collecting interface circuit,double voltage rectifier circuit,boost voltage regulator circuit and energy storage circuit.Thecircuits were analyzed and optimized using Multisim 14.0.At the same time,the schematic and PCB layout of the circuit were drawn with Altium Designer,and then manufactured.Finally,the circuit was verified through experiment.