Research Of Driving And Receiving Circuit Of Transducer For Low-Power Gas Ultrasonic Flowmeter

Compared with traditional mechanical meter, gas ultrasonic flow meter has the advantages of high measuring precision, wide measuring range, no pressure loss and so on. Low power products can also be applied to the areas that inconvenience of power supply, such as the desert and the field. With the increasing proportion of natural gas in China’s energy supply, it has very broad market prospects. However, gas ultrasonic flowmeter market has long been monopolized by foreign manufacturers, the independent research is of great significance.The excitation and receiving circuit of transducer is an important part of low power gas ultrasonic flowmeter, and it is also a current research issue. It triggers the transducer with high pressure and high efficiency, and processes the signal of the transducer to get the high precision time value of ultrasonic propagation. It also needs to solve many problems existing in the field application. The main research contents are as follows:The Design of multichannel transducer excitation circuit that based on high frequency transformer solves the problem that high attenuation of transducer signal in gas, including the Intrinsically safe design. By means of model analysis and AP method, this thesis realized the independent design of high frequency transformer. The matching network increases the efficiency of the driving circuit. Finally, the original receiving signal is relatively ideal.By optimizing design, the amplifier and filter circuit greatly enhances the amplitude and signal to noise ratio of the received signal. By using adaptive enable window technique that realized by wave selecting circuit combined with over-zero comparing technique, the stop timing signal is extracted accurately and interference signal is shielded very well.Low power automatic gain control technology solves the problem of pipeline pressure adaptability, digital isolator achieves low power and high speed communication isolation. The anti-interference performance of the circuit board is greatly improved by the multilayer board technology. By using the chips of ultra low power consumption and a reasonable low power measurement sequence, the circuit can work more than 4 years.Finally, this thesis contains sonic nozzle calibration experiment, high pressure ring road experiment and EMC experiment.They proved that the circuit has a high measurement accuracy, a good pipeline pressure adaptability and a good anti-interference performance.