基于FPGA的高精度多量程的电阻测量系统设计

Design of high precision multi-range resistance measurement system based on FPGA

针对现有电阻测量设备存在的精度低、量程小等问题,提出一种新的测量方法。该方法在测量小阻值电阻时运用恒流源测量法,并使用ADS1115多通道同时采集被测电阻及参考电阻端电压,比例计算,降低误差,加权平均;测量大电阻时将555振荡电路作为R-f转换电路,通过测频率间接测量电阻,提高测量精度,扩大测量量程。测试结果表明,在全量程范围内系统测量误差均小于0.1%。

In the view of the problems of existing resistance measurement equipment, such as low precision and small range, we put forward a new measuring method. Low resistance was measured by constant current source method. The voltage of resistance under test and the reference resistance were simultaneously collected by ADS1115 so as to do ratio calculation, reduce the error, measure the weighted average, and improve the accuracy of measurement. In measuring large resistance, we took 555 oscillation circuits as R-f conversion circuits. The resistance was indirectly measured by measuring the frequency of resistance. In this way, the measurement accuracy was improved and the measurement range enlarged. The test result shows that the measurement error was averagely less than 0.1% within full-scale range.