低温电流比较仪自动电阻电桥前馈系统设计

发布时间：2019-02-20 18:26

【摘要】：本文设计的低温电流比较仪(CCC)自动电阻电桥前馈系统没有接入DC-SQUID环节,即开环的低温电流比较仪。系统主要由四部分组成,即上位机配置程序、光隔离数字控制器、电流比较仪电流源电路以及前馈回路。低温电流比较仪自动电阻电桥中使用直流超导量子干涉器(DC-SQUID)作为反馈环节检测不平衡磁通量进而反馈调节电流比例。该器件线性工作范围较小,系统的稳定性易受影响。本文设计的开环系统通过上位机程序设置DA的参数可以调节电流比较仪的输出,并通过偏置DA的调节,可以大大提高输出电流比例的精度。另外本文针对该系统提出了一种开环测试方案,测试该系统输出能达到的最大的比率精度。主要测试了电流比较仪输出为1:100和1:1情况下,通过数据得出电流比例精度和稳定性。通过实验及数据分析,电流比较仪输出为1:1时,采集到的电阻电桥压差经过长期实验观察均在3μV以内,电流比较仪输出精度可以达到3×10-5,经过计算该情况下比例值标准偏差值为1×10-6。电流比较仪输出为1:100时,采集到的电阻电桥压差经过长期实验观察均在5μV以内,电流比较仪输出的比例精度可以达到5×10-5,经过计算该种情况下的标准偏差值为3×10-6。
[Abstract]:The low temperature current comparator (CCC) automatic resistive bridge feedforward system designed in this paper has no access to DC-SQUID link, that is, open loop low temperature current comparator. The system is mainly composed of four parts, that is, the upper computer configuration program, the optical isolation digital controller, the current source circuit of the current comparator and the feedforward circuit. DC superconducting quantum interferometer (DC-SQUID) is used as a feedback link to detect the unbalanced magnetic flux in the automatic resistive bridge of the low temperature current comparator and to adjust the current ratio by feedback. The linear range of the device is small, and the stability of the system is easy to be affected. The open-loop system designed in this paper can adjust the output of the current comparator by setting the parameters of DA by the upper computer program, and the accuracy of the output current ratio can be greatly improved by adjusting the bias DA. In addition, an open loop test scheme is proposed to test the maximum accuracy of the system output. The output of the current comparator is 1: 100 and 1:1, and the accuracy and stability of the current ratio are obtained by the data. Through experiment and data analysis, when the output of the current comparator is 1:1, the collected voltage difference of the resistive bridge is within 3 渭 V after long-term experimental observation, and the output precision of the current comparator can reach 3 脳 10 ~ (-5). The standard deviation of the proportional value is 1 脳 10 ~ (-6). When the output of the current comparator is 1: 100, the measured voltage difference of the resistive bridge is less than 5 渭 V after long-term experimental observation. The proportional accuracy of the current comparator can reach 5 脳 10 ~ (-5), and the standard deviation is 3 脳 10 ~ (-6).
【学位授予单位】：青岛大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB971

【相似文献】