Design And Performance Analysis Of Piezoelectro-magnetic Energy Collector In Low Frequency Vibration Environment

Low frequency vibration energy collection technology is widely used,mainly using piezoelectric effect,electromagnetic induction principle design of a variety of structures,the tidal energy,human motion kinetic energy,low-frequency special machinery and other low-frequency motion energy into electric energy,through the energy collection circuit for collection and storage,at the same time for low-power microelectronic devices power supply.In this paper,a piezoelectric electromagnetic composite low-frequency vibration energy collection device based on piezoelectric effect and electromagnetic induction principle is designed,which collects the low-frequency kinetic energy generated by human body.This paper studies the influence of relevant structural parameters and external environment on its output performance,and tests the output performance in combination with different human motion states.In order to realize the design of wearable vibration energy collection device for human motion energy collection,the human vibration acceleration collection device is designed firstly.The motion frequency of wrist and ankle under walking and jogging conditions is studied experimentally.According to the low-frequency motion characteristics of human body,the piezoelectric electromagnetic energy conversion structure is designed,The influence parameters of piezoelectric effect principle and electromagnetic induction principle are analyzed.The relationship between natural frequency and output power of piezoelectric electromagnetic energy conversion structure is derived.The influence of structural parameters and material properties on output power of energy conversion structure is analyzed.The finite element simulation model of electromagnetic energy conversion module is established,and the influence of induction coil size parameters,permanent magnet strength,rotating speed and other parameters on the output characteristics of electromagnetic energy conversion is analyzed.The test rig of the energy output characteristics of the electromagnetic induction module is built for verification of output characteristic,which provides a reference for the parameter selection of the electromagnetic energy conversion module.The finite element simulation model of piezoelectric energy conversion module is established,and the influence of structure size,material parameters,permanent magnet strength and other parameters on the output characteristics of piezoelectric energy conversion is analyzed.The results show that there is an optimal thickness ratio between the cantilever beam and the piezoelectric plate in the structural parameters,and the output energy of the piezoelectric module varies linearly with the material parameters,the distance between the permanent magnets in the external parameters,and the rotating speed of the rotating machinery.The energy collection experiments of piezoelectric energy conversion module and electromagnetic energy conversion module are carried out.The energy collection circuit based on boost chip is designed.The energy is stored by capacitor and rechargeable battery,and the output can be output with stable voltage.The maximum charging power of the capacitor is 0.9mw when the DC power supply is 500 mv,which verifies its effective collection of low-voltage AC energy.The function of rectifying and boosting the output voltage of energy conversion module by energy collection circuit is realized.The piezoelectric and electromagnetic energy conversion module and energy collection circuit are integrated into a small wearable piezoelectric electromagnetic energy collection device.In the human movement energy collection experiment,the maximum charging power of wrist and ankle are 0.0347 mw and 0.0274 mw,respectively.In this study,combined with the principle of electromagnetic induction and positive piezoelectric effect,piezoelectric electromagnetic composite power generation is realized,and a portable and wearable small piezoelectric electromagnetic composite energy collection device is designed,which improves the efficiency of energy collection,and provides theoretical and experimental basis for energy collection in low-frequency vibration environment and the research of wearable energy collection device.