Research On Low Power Gas Ultrasonic Flowmeter Based On MSP430 Microcontroller

Gas ultrasonic flowmeter is widely used in steam,storage handover,trade settlement,industrial and civil gas metering because of its high accuracy and versatility.In industrial and gas metering fields,measurement accuracy and system power consumption are important indicators of gas ultrasonic flowmeters.The main research contents of this topic are as follows:According to the low power selection principle,the consistency,sensitivity and proximity peak of the ultrasonic receiving signals of Airmar,Jiakang and Shouguang Feitian are tested.The feasibility of the low voltage excitation ultrasonic transducer was verified and the ultrasonic transducer selection is completed.A rectifying device was designed to optimize the structural size of the rectifier by means of fluid dynamics simulation.In the software and hardware design of low power gas ultrasonic flowmeter,the power module,ultrasonic transmitter module,ultrasonic receiving signal processing module and software measurement programs are designed.The hardware part focuses on the related design schemes to reduce the average operating current of the system while implementing the functions of each module of the measurement system.In addition,the software part optimizes the measurement process of the system,ensures the accuracy of the measurement results,and reduces the power consumption of the system by increasing the sleep time of the system.In the aspect of accurate time measurement method,the principles of classical double threshold trigger method and adaptive double threshold level method are introduced and their defects in solving the wrong wave problem are analyzed.By analyzing the received signals collected at different flow rates,a new method called the peak acquisition difference method to accurately identify the arrival time of the signal is proposed.In real flow experiments,the measurement performance of the three methods(double threshold trigger method,adaptive double threshold level method and peak acquisition difference method)at different flow rates is compared.When the flow velocity is greater than 10 m/s,the first two methods(double threshold trigger method and adaptive double threshold level method)have obvious wrong wave phenomena.However,the peak acquisition difference method can still obtain the desired propagation time when the flow rate is 25m/s.Based on the above aspects,the low power gas ultrasonic flowmeter based on MSP430 single-chip microcomputer is studied,and the real flow verification experiment is carried out.Finally,the measurement accuracy reaches 1 level in the flow rate range of 1m/s～25m/s,and the average operating current of the measurement system is about 6 mA.