Improved observer-based quadrature signal generator

Abstract

In this paper, an improved quadrature signal generator (QSG) parameter tuning procedure is proposed, based on a modification of an existing adaptive observer QSG algorithm. Namely, in the existing solution an observer-based QSG is proposed with a parameter tuning procedure that results in a bandwidth frequency equal to the QSG input signal frequency, while in this paper, a modification of this parameter tuning procedure is proposed that enables the QSG to operate with increased bandwidths. A comparative analysis is presented, which evaluates both the existing solution and the solution based on the novel observer parameter tuning algorithm. Also, it is shown that when existing and proposed observer-based QSG operates with bandwidths that surpass the input signal angular frequency, the high-pass resulting observer frequency characteristics are obtained. By using frequency responses, and simulation and experimental tests, which include basic QSG operation and the PLL based on the proposed QSG, the resulting improvements are presented and compared. Also, the adaptive observer-based QSG with improved parameter tuning procedure is employed in the positive sequence component separation algorithm for the nonsymmetrical three-phase system, which represents an original application this type of QSG structure.