ENHANCE THE ACCURACY OF FREQUENCY MEASUREMENT OF HARMONIC SIGNALS

Melent'ev Vladimir Sergeevich, doctor of technical sciences, professor, head of sub-department of information and measuring equipment, Samara State Technical University, vs_mel@mail.ru
Yaroslavkina Ekaterina Evgen'evna, candidate of technical sciences, associate professor, sub-department of information and measuring technique, Samara State Technical University, makarovak@inbox.ru
Burdukskiy Nikita Sergeevich, master degree student, Samara State Technical University, deadmaster65@gmail.com
Nefed'ev Dmitriy Ivanovich, doctor of technical sciences, head of sub-department of information and measuring equipment and metrology, Penza State University, iit@pnzgu.ru

621.317

The object of the research is the frequency of the periodic signal. The subject of this study is to determine the method of frequency measurement, based on the formation of additional signals which are shifted in phase relative to the input. The aim is to study a new method of measuring the frequency, which eliminates the possibility of frequency error and the formation of an additional voltage error of phase-shifting units. To determine the frequency used only instantaneous values of the input voltage, and additional signals apply only to reduce measurement time. When analyzing the error due to the deviation of the actual signals from the harmonic model, used a technique based on the estimation of the error of the measurement result parameter as a function whose arguments are given with an accuracy of approximately corresponding to the deviation from the model of a real signal. The approach to determining the frequency based on the detection of characteristic points of the additional signals and measuring the instantaneous values of the input signal at its zero crossing. This approach allowed the development of a method which, in contrast, by the majority of the known methods based on the formation of additional signals, use only the instantaneous values of the input voltage. The influence of the angular error of the phase-shifting blocks on the resulting error in determining frequency is considered. When implementing the developed method uses only one analog-todigital converter, which reduces the hardware expenses. The obtained results of analysis of influence of errors caused by deviation of the actual signal from the harmonic model, and angular error of phase shifting unit for determining the frequency error results, allow to choose the optimal parameters of the measuring process depending on the requirements for accuracy and measurement time.

frequency, harmonic model, the instantaneous values, additional signals, the phase-shifting block, an error, deviation of the actual signal from model.