Design And Experimental Research Of Temperature Measurement System Powered By Piezoelectric Energy Harvester

As one of the most important industries in the national economy,agriculture is the source of food and clothing for human beings and fundamental to their survival.With the rapid development of agriculture,the number of agricultural greenhouses in my country is increasing.Currently,the two main methods used for temperature measurement are thermometer measurement and sensor acquisition.The temperature data measured by the thermometer needs to be read manually which is not accurate enough.Some of the sensor equipment used for temperature measurement is still powered by chemical batteries.Not only the need for regular battery replacement,and pollution of the environment can not be underestimated.This article proposes using piezoelectric energy harvesting technology to replace traditional batteries for temperature sensors.The main contents of this paper are as follows:（1）Firstly,the piezoelectric cantilever beam power generation device is analyzed,and the resonance frequency of the piezoelectric cantilever beam is 26.8 Hz,within the vibration frequency range of the air outlet of the greenhouse.Cantilever piezoelectric capacitor is charged at the resonant frequency,2 hours charge,The electric energy stored in the capacitor is 2.68×10^-2J.Collection efficiency and output characteristics of the interface circuit of the energy collection different were simulated and the actual verification,On the basis of comparing energy harvesting circuits with different,an energy harvesting interface circuit based on peak detection of reed switches is designed.The circuit can stably output a voltage of 4 V.After charging for 10 minutes,14.25×10^-2J of energy stored in the capacitor,and the collection efficiency is 32 times that of the full-bridge rectifier circuit.Input voltage and the output voltage of the energy management chip LTC3588-1 acquisition circuit 2.7 V～20 V pertinence,realize the stable conversion function of energy.（2）From the perspective of the application of actual agricultural engineering,the design requirements of the temperature measurement system in this study are clarified,and the overall design plan of the system is determined according to the design requirements.In terms of hardware circuit design,complete the selection of temperature sensors,microcontrollers and wireless transmission modules,Temperature measurement circuit optimization design of the overall system;In terms of software program development,completed the program design including temperature acquisition,data processing and wireless transmission.The final online after the program debugging downloaded to the development board test program is running well.（3）Draw system circuit schematic diagrams and PCB board diagrams,and process the drawn board diagrams to make physical objects.By setting up a corresponding test platform,the test results show that:In working mode,the power consumed by the entire system is 952.05μW,and the power consumed in sleep mode is 6.765μW.The piezoelectric vibration energy harvester power output sufficient power to the temperature sensor acquisition system,and finally compare the accuracy of temperature measurement,temperature monitoring achieved.It is verified that the method of using piezoelectric energy harvesting technology to convert mechanical vibration energy into electrical energy to supply power to the sensor is feasible and efficient.