| Abstract |
Phase-locked Loop (PLL) systems have been widely used in many applications involving automatic
control, such as communications, instrumentation and electric drives. This paper presents a detailed
study of a PLL structure for three-phase grid-tied systems. Its operation under utility distorted
conditions is analyzed, as well as its ability to give quasi-instantaneous information of phase,
frequency and amplitude of the utility voltages. Additionally, a new PLL structure for single-phase
systems is introduced. This new PLL is compared with the conventional zero-crossing PLL type.
Small signal models and dynamic stiffness characteristics for the PLL's are presented. Experimental
results from a DSP-based system are included to support the theoretical analysis. |
