A Novel Quadrature-Signal-Generator Based on Sliding-Mode Discrete Fourier Transform

In this paper, a novel Quadrature-Signal-Generator (QSG) for single-phase synchronization systems based on frequency aligned Discrete Fourier Transform (DFT) is presented. Mathematical background of this new algorithm is shown including the adjustment that has to be done to remove the errors in DFT due to off-nominal frequency operations. It was shown that this adjustment depends on frequency measurement so a frequency estimator with high accuracy is used. This new Quadrature Signal Generator is used to directly extract magnitude and phase information of the input signal, without the need for feedback-based structures like PLL or FLL. Several standard tests are performed and it was shown that this new method in its basic form is comparable or outperforms most of the advanced methods used today.