Three-Phase PLLs: A Review of Recent Advances

A phase-locked loop (PLL) is a nonlinear negative-feedback control system that synchronizes its output in frequency as well as in phase with its input. PLLs are now widely used for the synchronization of power-electronics-based converters and also for monitoring and control purposes in different engineering fields. In recent years, there have been many attempts to design more advanced PLLs for three-phase applications. The aim of this paper is to provide overviews of these attempts, which can be very useful for engineers and academic researchers.