Research On Electromagnetic Vibration Energy Harvester Based On Bi-stable Cantilever Beam

In recent years,MEMS technology has become more and more mature,with the rapid development of large-scale integrated circuit and microelectronic technology,electronic devices and circuitry systems are evolving to a state with miniature and low consumption.Generally,electronic equipment takes traditional battery as its power source,however,the battery has the defects of low energy storage,short life and high quality,needed to be replaced or charged frequently.The working environment of micro-electronic equipment is uncertain,the demand for its power source is getting higher and higher.Therefore,how to provide self-powered equipment for micro-electronic equipment or increase its duration is urgently needed.At present,researchers all over the world are constantly exploring innovative power supply methods,in which the way of translating vibrational energy in environment to electrical energy,namely the so-called energy harvesting technology,has gradually become a research hotspot.In the development of VEH,the electromagnetic VEH based on Faraday's law of electromagnetic induction has many advantages,which is of great research value.Compared with other vibration pickup structures,bi-stable cantilever has advantages of low stiffness,wide response frequency bandwidth,high environmental sensitivity and adaptability.Therefore,the electromagnetic VEH based on bi-stable cantilever beam has become a main method in research of VEH.This paper focuses on electromagnetic VEH based on bi-stable cantilever beam consisting of two pieces of magnet,its bi-stable response characteristics and energy harvesting methods are explored from the aspects of dynamic characteristics,non-linear magnetic force and potential function.The main results of the study are as follows:1.Introducing shape correction function and magnetizing current method into the nonlinear magnetic analysis model to discussing dynamic characteristics of bi-stable cantilever beam system in detail,which can reduce the error between theoretical calculation and experimental measurement of this system's potential function and vibration response.2.The effects of different excitation intensities and magnet interval on the vibration response of bi-stable cantilever beam are studied respectively.A set of optimum excitation intensity and magnet interval which can make the vibration response of the cantilever beam reach bi-stable state are obtained,and the relationship between the optimum magnet interval and excitation intensity is given.3.According to Faraday's principle of electromagnetic induction,the conversion formula between the relative coordinates and the absolute coordinates under moving coordinate system with the center of the magnet at the free end of the cantilever beam as its coordinate origin is established,and the accurate calculation method of the electromagnetic induction voltage in the coil is obtained.4.The numerical simulation and experimental is accomplished to investigate that the analysis of nonlinear magnetic force,magnetic field and the simulation calculation of the vibration response and induced voltage of the bi-stable cantilever beam are correct,which can provide effective evaluation for induction voltage and output power of electromagnetic VEH based on bi-stable cantilever.