Research On Piezoelectric Vibration Energy Harvesting System For Self-powered Sensors

In recent years,with the rapid development of MEMS and wireless network transmission technologies,small wireless sensor systems have begun to be applied in many fields.The use of ordinary batteries as the power source for such sensors has many problems such as large mass,large size,short life,and need to be periodically replaced.Therefore,how to realize the self-power supply of micro-sensor system is one of the hot spots in this field.This paper is aimed at a wireless self-powered sensor for vibration monitoring of mechanical equipment.Starting from the overall system design,the energy consumption requirements of the system are determined through component selection,circuit design and power consumption analysis.And the structure was analyzed and designed.First,the overall scheme of the self-powered wireless sensor system was determined,including hardware selection and circuit design of the sensor,micro power processor and wireless transmitter module.Among them,the sensor uses piezoelectric sensor,the microprocessor selects MSP430f micro-power processor,and the radio frequency module selects CC1101 chip to realize data transmission and reception.Through the system operating conditions and energy consumption analysis,the power requirement of the system under the transmission condition is 109.662mW,0.99×10-3mW under the sleep condition and 70.062mW under the receiving condition.In order to achieve the above system energy requirements,a drum-type piezoelectric film energy harvesting device is used as the power supply system.Through theoretical derivation and simulation analysis,the influence of structural parameters of drum energy collector,external vibration load and load circuit parameters on power supply performance is obtained.According to the finite element calculation,the energy collecting device with a diameter of 4cm can output 7.11?W when the external excitation acceleration is 25m/s~2 and the external circuit optimal load is 0.5 M?.In order to improve the power supply performance,the piezoelectric energy harvesting device is structurally optimized by means of reinforcement.Through simulation comparison,it is found that the output power of the reinforced structure is 1.68?W higher than that of the unreinforced structure under the same working condition,and the power generation performance is increased by 23.62%.At the same time,the paper also studies the series-parallel mode of the two-layer piezoelectric power generation structure.The simulation results show that the series-parallel method can improve the power generation efficiency but the corresponding optimal matching load is different.Finally,the piezoelectric energy supply device was experimentally studied,and the piezoelectric energy supply device was fabricated to build a dynamic experimental platform.The electric energy output test was performed on different piezoelectric energy supply devices and compared with the finite element simulation results.Through the piezoelectric energy supply device and the standard energy harvesting circuit,the power generation performance of the system is analyzed.It can be seen that when the storage capacitor is 470?F,the 800s of energy can be collected for the entire wireless sensing system to run for 59.1ms.In theory,the whole sensor can be realized.The requirement for intermittent power supply in the system.