Interpolated Zero-padded FFT Algorithm for Harmonic Analysis Based on Zero-padded Window Function Fitting

Fast Fourier transform (FFT) is commonly used in engineering for harmonic analysis due to relatively low computational complexity. However, FFT make sure that the length of the data must satisfy certain conditions, such as 2/3/4 or other inter powers. Aiming at the fact that the length of the data window is a non-integer power, an improved interpolated zero-padded FFT harmonic measurement algorithm is proposed. The core of the algorithm is to transform the interpolation correction of the zero-padded FFT into the fitting correction of the spectral response based on the zero-padded window function. 5-term maximum side lobe decay speed window is used to correct the data. The proposed algorithm is suitable for any zero-padded window function and avoids to derive a modified formula. Simulation and experimental results verify the effectiveness of the algorithm in harmonic analysis.