Implementing Digital Filters and DSP Micro-Controller for Estimating the Frequency of a Time-Domain Signal

摘要

Accurate frequency estimation plays an important role in many applications, like power grids, micro-grid integration etc. This paper aims to estimate the frequency of a voltage signal at a certain frequency, with the help of another signal. The frequency of the other signal is kept close to the signal under test. The product is obtained, so as to get two components, the difference frequency component and the sum frequency component. This paper deals with the difference and the sum frequency component obtained, so as to get estimates of the frequency of the voltage signal source. To achieve this, a Low-Pass (LP) digital filter extracts the difference frequency signal and a Band-Pass (BP) digital filter extracts the sum frequency signal. Both are Butter-worth type of filters. This approach can also be used to analyze a power system waveform/signal that contains harmonics. This paper uses Texas Instruments' TMS320F28379d micro-controller unit to extract the difference and sum frequencies of the two sources. For further validation of the approach, MATLAB/Simulink based software simulations are also provided. Digital filters design is also discussed briefly.