基于TDC-GP2的超声波气体流量计的研制  

Development of Ultrasonic Gas Flowmeter Based on TDC-GP2

作　　者：史晓明 万峰 

机构地区：[1]河北工业大学机械工程学院,天津300130

出　　处：《仪表技术与传感器》2017年第11期120-126,共7页Instrument Technique and Sensor

摘　　要：针对传统型超声波气体流量计精度不高的弱点,提出一种基于TDC-GP2时间芯片测量的系统设计,采用时差法测量原理,选用大口径晶片(直径15 mm)的超声波换能器,采用单一正电源供电的设计思路,基于中点电压法设计同相放大电路获取初级超声波信号,基于反相放大器的自动增益控制(AGC)电路实现信号幅度的恒定,设计了二阶带通滤波器电路用于放大电路产生噪声的滤除,设计了阈值可变的比较电路从而准确产生了用于计时的方波,并控制时间芯片TDC-GP2实现了时间差的精确测量。对整个硬件系统进行了测试,结果显示超声波气体流量计的精度达到1级。Traditional ultrasonic gas flowmeter has the weakness of low accuracy.A new flowmeter system based on TDC-GP2 time measurement chip was proposed in this paper.Time difference method for measuring gas flow was used. An ultrasonic transducer with large diameter wafer（ 15 mm diameter） was selected. Positive power supplies were used in this design for the use of negative power leading to large noise.Based on midpoint voltage method,a non-inverse amplifying circuit was designed to obtain the primary ultrasonic signal.An inverting amplifier based on automatic gain control（ AGC） circuit was designed to keep amplitude of the signal constant.A second-order band-pass filter circuit was designed to filter the noise.Variable threshold comparison circuit was designed to produce the timing square wave accurately,which controlled the TDC-GP2 time chip to realize the accurate measurement of time lag.The whole system was tested,the result shows that the precision of the gas ultrasonic flowmeter can reach level 1.

关 键 词：超声波 气体流量计 时间芯片 

分 类 号：TH814[机械工程—仪器科学与技术]