高精度通用型混合采集电路设计

Design of High Precision Universal Hybrid Acquisition Circuit

针对数据混合采集系统存在不适用性,采集精度低的问题,设计了一种通用性高,采集和隔离采集混合采集系统。系统各个板卡之间由板间连接器对插级联,增强了通用性和可扩展性。在原有采集卡的基础上增加隔离采集卡,隔离采集是对同类不同路输入信号、不同类信号、待采集信号和模拟开关做隔离处理。硬件方面由主控卡FPGA统一控制采集,只用一级模拟开关选通;采用线性光耦隔离待采集信号与模拟开关,DC/DC提供不同隔离电源,数字隔离器隔离控制信号,这些措施减小了信号震荡,降低了分层值,提高了采集精度。软件方面改进了ROM表的编码规则,简化了硬件电路,释放了负载压力;通过分析AD采集时序,做到精准采样转换。经试验验证,该设计采集精度可以满足3‰精度要求,具有较高的使用价值,现已被工程采用。

Aiming at the problems of inapplicability and low acquisition accuracy of data hybrid acquisition system,a hybrid acquisition system with high universality,acquisition and isolation acquisition is designed.Each board of the system is cascaded by inter board connectors to enhance universality and scalability.An isolation acquisition card is added on the basis of the original acquisition card.Isolation acquisition is to isolate the same and different input signals,different types of signals,signals to be collected and analog switches.In terms of hardware,the acquisition is uniformly controlled by the main control card FPGA,and only one-level analog switch is used for gating.The linear optocoupler is used to isolate the signal to be collected from the analog switch,DC/DC provides different isolation power supplies,and the Digital Isolator isolates the control signal.These measures reduce the signal oscillation,reduce the layered value,and improve the acquisition accuracy.In terms of software,the coding rules of ROM table are improved,the hardware circuit is simplified,and the load pressure is released.Accurate sampling conversion is achieved by analyzing AD acquisition timing.The test shows that the acquisition accuracy of the design can meet the accuracy requirement of 3‰and has high application value.It has been adopted in engineering.