基于辅助阻抗匹配支路的超声波时差测量系统

Ultrasonic time-difference measurement system based on auxiliary impedance matching circuits

为了抑制超声波时差测量系统的静态时间差,本文提出了一种基于辅助阻抗匹配支路的新型拓扑结构,并最终基于该拓扑结构成功研制出了一台超声波时差测量系统样机。基于样机和自制的换能器,分别进行了不同驱动频率、不同匹配电阻以及高温工况下(200℃、230℃和260℃)的静态时间差的测试,并通过实流标定实验验证了整套系统的精度和可行性。结果表明,通过辅助阻抗匹配支路的加入能够有效的抑制系统静态时差的均值及其波动范围,且在200℃、230℃和260℃的高温环境下实现了最低-0.279 ns的静态时差。最终,系统在低流量440 m^(3)/h处精度等级可达0.15%,中、高流量1503~4397 m^(3)/h范围内精度可达0.05%,验证了辅助阻抗匹配支路的可行性,为超声波时差测量提供了一种高精度和低静态时差的解决方案。

To suppress the static time error of the ultrasonic time-difference measurement system,this paper proposes a new topology based on the auxiliary impedance matching branch,and finally a prototype ultrasonic time-difference measurement system is successfully developed based on this topology.Based on the prototype and the homemade transducer,the static time errors at different driving frequencies,different matching resistances and high-temperature operating conditions(200℃,230℃ and 260℃)were tested,and the accuracy and feasibility of the whole set of system were verified by the real-flow calibration experiments.The results show that the mean value of the system static time error and its fluctuation range can be effectively suppressed by the incorporation of the auxiliary impedance matching branch,and a minimum static time error of-0.279 ns is realized under the high-temperature environments of 200℃,230℃ and 260℃.Finally,this system achieves an accuracy level of up to 0.15% at a low flow rate of 440 m^(3)/h,and an accuracy of up to 0.05% in the range of medium and high flow rates of 1503~4397 m^(3)/h,which verifies the feasibility of the auxiliary impedance matching branch,and provides a high-precision and low static time difference solution for ultrasonic time difference measurement.