一种高精度电阻测量仪系统设计

摘要

In order to realize the precision measuring of resistance, a high accuracy resistance measuring instrument system was designed. This system used MCU as the core of control. Different standard resistance were connected to high accuracy constant voltage resource so as to create a series of high accuracy constant current which operated though the resistance under test. The voltage on the resistance under test measured by four-terminal measuring technique was converted to digital signal by A/D converter so that the value of the resistance could be worked out. This system can change measuring grades and numbers of significant digits automatically with a range about 3m-3MΩ. When the measurement speed is 15 times per-second, it can achieve the accuracy of 0. 5 %, and maintain the digits of change under 3.%为了实现对电阻的精确测量,设计了一种高精度电阻测量仪系统.该系统使用单片机作为控制核心,高精度恒压源通过标准电阻产生高精度标准恒流源作用在待测电阻上,采用四端法测量待测电阻两端电压,使用低速高精度A/D读取电压值,实现电阻的低成本、高精度测量.该测试仪可自动变换测量档位和显示有效位数,量程范围为3 mΩ～3 MΩ.实测结果表明,测试速度在15次/s时,测量精度达到0.5％,读数跳动在3字以下.