Research On Ultrasonic Liquid Temperature Measurement System Based On TDC

Ultrasonic temperature measurement technology has attracted a large number of domestic and foreign researchers to conduct in-depth research on it with the advantages of high accuracy,fast response,non-contact,and low cost.Aiming at the deficiencies of measurement accuracy and resolution of traditional temperature measurement instruments,a high-resolution and high-reliability ultrasonic temperature measurement system is designed by using FPGA chip as the main control chip,combined with TDC(Time-to-Digital Converter)technology and modularization idea,with the research goal of improving the accuracy and resolution of temperature measurement.The main research contents of this topic are as follows.Firstly,the propagation characteristics of ultrasonic waves are analyzed,the selection of sensors is carried out,the principle of ultrasonic temperature measurement is derived using mathematical equations,and three different time measurement methods are introduced in detail in terms of structure.The advantages and disadvantages of each time measurement scheme are compared,and the tapped delay chain measurement scheme suitable for this design is selected.Secondly,the hardware design of the system is unfolded from the structural level,and the functions of each hardware module are analyzed.The design of hardware circuits is presented one by one in the logical order of data acquisition.The master control module controls the logic of the whole system,arbitrates the work of each module,controls the time measurement circuit to measure the ultrasonic wave propagation time,controls the signal processing circuit to process the echo signal,stores the data to the SDRAM storage circuit,then uploads the data to the upper computer for display through the communication circuit,and the power supply module provides voltage to the whole system.Finally,the driving timing of the hardware module is described in detail.Based on the hardware module,the timing of the hardware module needs to be driven.The system is programmed using Verilog language to drive the timing of the protocol and implement the register configuration to complete the logic design.In addition,the MATLAB tool is used to process the data for larger error value rejection and finally display the measurement results in the upper computer.Based on the hardware platform and software design,the experimental platform was built,and the time measurement module was debugged and the ultrasonic signal was observed to verify the system into normal operation.Then the temperature measurement error and temperature measurement resolution experiments were conducted to verify that the system has temperature measurement function.The final experimental results show that the temperature measurement error of the system is within 1℃,the resolution of ultrasonic propagation time is within ±0.15 ns,as well as the ultrasonic temperature measurement resolution can be better than 0.001℃.