The Design And Analysis Of Flexible Energy Harvesting System

The flexible energy harvesting system no longer has harsh demands on the frequency and amplitude of excitation.This is to say,it should be easily obtained in the nature with low frequency and amplitude vibration.Due to the limitation of the transducer itself,the output voltage is not very high with low frequency and amplitude vibration excitation,which results in low energy conversion efficiency.In an energy harvesting system,an interface circuit is essential.This thesis mainly focus on the research of ultra low input voltage to boost with self-driving ability.This paper emphases the following aspects:(1)Summarizing most of the previous literature,it can be found that the research mainly focuses on four aspects: research on optimal duty in PWM control,different kinds of circuit topology,the study of active,semi-active and passive control circuits,the study of special integrated circuit for energy harvesting technique.(2)The classical energy harvesting structure is setup and its power is 8.7 ?W.By analyzing experimental conditions and results,the reasons for low energy harvesting efficiency are explained.The characteristics of the interface are proposed: it should have the ability to complete the task of energy conversion independently and efficiently.Other practical cases also support this view.(3)Two kinds of self-driving circuit topology are proposed,and a detailed introduction to the working principle of the circuits is taken.The feasibility of the circuits is demonstrated in theory and simulation.It can boost the voltage as low as 0.3V.It also explains the circuits from the view of control.Besides,PCB is also made in this thesis.The experimental result shows that the circuits can work when the input voltage is as low as 0.5V.(4)On the basis of self-driving circuits,the ultra low input voltage setup circuits are studied.By analyzing the different kinds of the ultra low input voltage setup circuits topology,an ultra low input voltage setup circuit with self-driving is established for the piezoelectric energy harvesting(PEH)technique.It can convert the input voltage as low as 0.3V to 3.3V independently.And its output power can reach up to 3.9 mW.It is also discussed that the significance of it to the flexible PEH.