4 research outputs found
Comparative analysis between different approaches for single-phase PLLs
"In press"This paper presents a comparative analysis between
two distinct synchronizing circuits, which are usually applied as
the core of control algorithms for single-phase power quality
applications. One of these synchronizing circuits corresponds to a
single-phase Phase-Locked Loop (PLL), implemented in α-β
coordinates (αβ-PLL), whereas the other one corresponds to the
Enhanced PLL (E-PLL). The major contribution of this paper is
to present a single-phase PLL oriented to power quality
applications, with a very simple structure, capable to be
synchronized with the fundamental component of an input signal
(voltage or current), even considering substantial disturbances,
such as, frequency deviations, phase shifts, harmonic components
and amplitude variations. Simulation and experimental results,
involving these two synchronizing circuits submitted to three
different test cases, are provided in order to compare their
transient and steady-state performance. Moreover, it is also
presented a comparison involving the processing speed and
memory requirements of these synchronizing circuits in the DSP
TMS320F28335
Modeling and Analysis of SOGI-PLL/FLL-based Synchronization Units: Stability Impacts of Different Frequency-feedback Paths
— Second-order Generalized Integrator (SOGI)-based quadrature-signal-generator (QSG) together with either a phaselocked-loop (PLL) or a frequency-locked-loop (FLL) constitute two types of typical synchronization units (i.e., SOGI-PLL and - FLL) that have been widely used in grid-tied converter systems. This paper will reveal and clarify the stability issue of these two synchronization units arising from different implementations of the frequency-feedback-path (FFP) connecting the SOGI-QSG and the PLL/FLL. In this regard, four types of FFP implementations that are frequently seen in the literature will be discussed. Although different implementations of the FFP will not affect the steady-state frequency adaptation, their dynamical effects on the small-signal stability of SOGI-PLL/FLL remain concealed. To this end, this paper will present a comprehensive stability assessment and comparative analysis of SOGI-PLL/FLL focusing on the FFP issue. To extend the applicability and accuracy of discussions, all the analyses will be fulfilled by using a parameter space-oriented stability assessment method formulated in the linear-time periodic (LTP) framework. The obtained results are verified by time-domain simulations, and the main findings are further interpreted by using appropriate analytical models. Index Terms— FLL, PLL, synchronization, SOGI, stability, LTP, frequency feedback.acceptedVersio