Sinusoidal signal estimation from a noisy-biased measurement by an enhanced PLL with generalized error filtering

In this paper, an Enhanced Phase-Locked Loop (EPLL) architecture is proposed to deal with the problem of estimating the amplitude, the frequency and the phase of a sinusoidal signal from a noisy measurement. The EPLL scheme is chacterized by an error filter and a phase-feedforward term that are embedded in the estimation algorithm for improved noise rejection and transient performances. By designing the error filter and by selecting the parameters of the PLL according to the guidelines suggested by the stability proof, the technique addressed in the paper allows to cope with the presence of measurement bias while damping the effect of high-frequency noise and harmonics. Simulation comparisons show the effectiveness of the proposed estimation technique.