Digital AC Voltmeter Error Caused by Level Quantization
DOI:
https://doi.org/10.14529/power190415Keywords:
digital voltmeter, quantization error, ADC module, discrete signal, level of error, measured signalAbstract
A digital AC voltmeter design requires determining the optimal configuration of the electronics used.
This electronics allows achieving the required characteristics, and its configuration shall be based on the parameters of the device set in the tonic task. Among other characteristics, a designer shall account for the device accuracy. In addition to noise and outside interference, the hardware methodological error is the basis that determines the maximum available measurement accuracy. The article presents a solution to a problem of choosing the minimum allowable bit depth of quantization by level, taking into account the known measurement range and the expected accuracy class. A model and methodological error of quantization by level is obtained and tested. The article also presents the results the cases when time quantization of a digital AC voltmeter are accounted for. The dependence of the error on the ratio of the minimum measured amplitude of the signal to the quantization step of the ADC is found. The paper describes the analytical models of level quantization error obtained for the output of a digital voltmeter for an ideal low-pass filter. The designed expressions are the basis to determine the minimum allowable step for quantizing the ADC or DAC for a known acceptable level of error and minimum amplitude of the input signal without respect to time and noise quantization in the measured signal, provided that the voltage measurement method is sampling it by time and level by means of the ADC.
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