数字微差补偿器及其在电流比较仪电桥中的应用

设计一种能够在四象限内对输出信号进行调节的数字微差补偿器,核心器件为16 位串行输入乘法型数模转换器,以正弦电压信号作为参考,可根据接收的数字编码分别调节输出补偿信号的同相分量和正交分量。提出一款计算机控制的电流比较仪电桥线路,应用数字微差补偿器和牛顿迭代算法实现电流比较仪磁势的自动平衡。利用研制的电桥对双螺线型计算电阻进行测量,结果表明,该电桥在1592 Hz频率范围内的标准测量不确定度为2×10^-7,能够满足交流电阻量值传递要求。

A Digital Compensator and Its Application in Current-comparator Bridge

A digital compensator is designed to output regulated signal in four-quadrant and its core component is two 16-bit serial input multiplying digital-to-analog converters. With sinusoidal reference signal, the in-phase and the quadrature component of the output can be adjusted in accordance with the given code. A computer controlled current-comparator bridge is developed and magnetic potential self-balance can be got by applying the digital compensator and Newton iteration algorithm. The AC/DC relative difference of bifilar helix resistors are measured below 1592 Hz through the proposed bridge using substitution method, and the standard measurement uncertainty is 2×10^-7 that can meet the requirement for quantity value dissemination of AC resistance.