Design And Analysis Of Energy Management Circuit For Vibration Energy Harveste

With the development of the internet technology and the wireless sensing network(WSN),a great deal of sensing devices are widely used in human production and life.However,traditional sensing devices need external power supply,which is not easy to carry and use.Therefore,a sensing device that can realize passive self power supply is needed.Traditional batteries,as power supply sensing devices,do not accord with the theme of the times because of their disadvantages such as large volume,short application cycle and large environmental pollution,so people urgently need a new green and sustainable energy supply method.The mechanical energy captured by vibration is easy to obtain and is green and pollution-free.Therefore,the vibration energy collection of piezoelectric materials is researched and favored by experts from all over the world.At present,for the energy captured by the vibration energy harvester,a circuit terminal is usually used for energy harvesting.However,because the mechanical structure of the circuit end and the vibration energy harvester cannot be well matched,the harvesting efficiency of the circuit is not very ideal.Starting from the mechanical model of the vibration energy trap,this paper establishes an equivalent circuit model highly matching the mechanical structure of the vibration energy trap through dynamic analysis and piezoelectric effect equations,and then designs the corresponding energy management circuit based on this circuit model.And analyze the output characteristics of the circuit,showing the advantages and energy capture efficiency of different energy management circuits.The main research contents of this article are:(1)The background of domestic and international research on piezoelectric energy harvesters,the current status of domestic and international research,the problems and shortcomings and the innovation points of this thesis are introduced.(2)On the basis of mastering the working principle and theory of vibration energy trap(such as piezoelectric effect,piezoelectric equation and other parameters),the mechanical model of vibration energy trap is established and finite element analysis is carried out to obtain the relationship between output voltage and output power under different vibration frequencies,accelerations and loads.Finally,the designed mechanical mechanism is optimized and analyzed,using the control variable method,and the effects of different substrate lengths,thicknesses and mass block heights on the overall structural performance are specifically analyzed.(3)The energy harvesting system model is established based on the related theory of force-electricity coupling,and the equation of motion is established through dynamic analysis,and the equivalent circuit of the mechanical part is deduced and verified for correctness so that the foundation for realizing the matching between the mechanical model and the circuit is laid.(4)To address the problem of impedance matching,an energy management circuit is proposed to achieve adaptive impedance matching.In this circuit,the peak detection module can effectively distinguish the different stages of energy collector vibration,and a 555 timer is used to generate the duty cycle and then control the Buck-boost circuit to achieve adaptive impedance matching.(5)An energy management circuit based on maximum power tracking(MPPT)and parallel synchronous switching inductor technology(P-SSHI)is proposed.MPPT technology is used for feedback control with output voltage and impedance matching is realized by controlling voltage to maximize power.