This paper presents approaches for efficient modeling and systematic design of enhanced phase-locked loop (ePLL) structures. While different ePLL structures have found a wide acceptance for various applications, their modeling and design aspects have not been fully and systematically reported in existing references. This paper fills this gap by presenting an effective modeling approach for both single-phase and threephase ePLLs. The models are derived with a view to minimize the number of parameters to be adjusted to simplify the design.