基于零磁通电流传感的自动电阻电桥设计

摘要

因商用直流电流比较仪(DCC)精度高、结构复杂、成本高昂,基于商用零磁通电流传感器基础上研制了一套直流比较仪自动电阻电桥,以降低成本、满足电阻测量精度要求较低应用场合的需求;围绕零磁通电流传感器的原、副边线圈安匝平衡机制下,其原、副边电流比例一定的特点,设计了自动电阻电桥电路;采用基于DSP的嵌入式数字电路实现系统控制和算法,使用自制且经过校准的24位AD采集电路读取电桥中电阻两端的压差信号,经实时处理及屏幕显示,最终得到被测电阻(Rx)和标准电阻值(Rs)的比例值;采用经校准过的标准电阻(Rs)对该电阻电桥100 Ω:10 Ω和10 Ω:1 Ω的比例进行校准,实验结果表明:该电阻电桥测量的比例准确度可达10-6量级,测量的相对标准差为10-6～10-7量级.%Based on the commercial zero-flux DC measuring system to develop a set of DC current comparator automatic resistance bridge to reduce costs and satisfy the application of low precision of resistance measurement conditions.Around the ampere-turns balance of the zero-flux DC measuring system,automatic resistance bridge circuit is designed.Using the embedded digital circuit based on DSP to realize the control system and algorithm,and using homemade and calibrated 24 AD data acquisition circuit to read the differential voltage signal of the the resistance in the bridge.By the real-time processing and display,and ultimately get the ratio of the resistance value and standard resistance.Using the calibrated standard resistance to correct the bridge of 100 Ω:10 Ω and 10 Ω:1 Ω,proportion accuracy reached orders of magnitude at 10-6,and relative standard deviation of the measurement for 10-6 ～10-7.