基于双电荷放大器的数字式两线制HART涡街流量变送器

针对耐高温涡街流量传感器灵敏度低及引入HART通信增加数字式两线制仪表的功耗且通信稳定性容易受电源影响的问题,研制了基于双电荷放大器的数字式两线制HART涡街流量变送器。采用两级电荷放大器和两级低通滤波器的信号调理电路,对耐高温涡街流量传感器输出的幅值较小的信号进行放大和滤波,获得稳定的流量信号;采用两路隔离电源的电源设计方案,提高电源的负载能力,并保证通信的稳定性,在进行数字信号处理的同时,实现两线制HART通信。实验结果表明,该变送器测量精度较高、量程下限较低,且满足低功耗要求。

Digital Two-wire HART Vortex Flowmeter Transmitter Based on Double Charge Amplifier

A digital two wire HART vortex flowmeter transmitter based on double charge amplifiers is developed in order to solve the problems that there is low sensitivity in the high temperature resistant vortex flowmeter sensor, and HART communication increases power consumption and its stability is easily affected by the power. The signal conditioning circuit concluding two-stage charge amplifier and two-stage low-pass filter is designed to amplify and filter the low output amplitude of high temperature resistant vortex flow sensor, and obtain the stable flow signal. Two isolated power supply scheme is adopted to improve load ability of power supply and ensure the stability of the communication, which achieves two-wire HART communication during the digital signal processing. The experimental results show that the transmitter possesses high measurement accuracy, small measurable low limit, and also meets the requirements of power consumption.