The Improvement of the ANF Performance in Frequency Estimation of Periodic Signals

Adaptive notch filter is a well-known approach for frequency estimation and extraction of sinusoidal signals. The structure of ANF is composed of a second order band-pass filter (BPF) (and its complementary notch filter) and a frequency update law that continuously adjusts the center frequency of the BPF. The performance of the ANF degrades when the sinusoidal input is polluted by some harmonics. In this paper، a method has been proposed to improve the performance of the ANF in the presence of harmonics. The proposed method is based on the use of a window function in the frequency update law. Window functions have extensively been used in some algorithms like discrete Fourier transform and phase-locked loop to provide better estimation of the parameters of sinusoidal signal in the presence of harmonics. It was shown that using a rectangular window enhances the ANF performance.