Input Admittance Analysis of SEPIC Power Factor Correction Grid-Connected Rectifier

This paper validates the input admittance of a SEPIC power factor correction (PFC) rectifier derived from an average model and a switching model. The SEPIC PFC rectifier is implemented and analyzed using both switching and average models in accordance with the specifications provided. PR and PI controllers are integrated into both models to evaluate their performance in regulating the input current and output voltage. A frequency response estimation method is employed to characterize the input admittance, applying small-signal perturbations to determine the system’s behavior over a broad frequency range. The results from the switching model show strong agreement with the average model for the input admittance, thereby validating the theoretical models. The open-loop input admittance exhibits three resonances at specific frequencies due to system dynamics, while the closed-loop configurations demonstrate variations in resonance and inductive behavior depending on the controller used. The findings indicate that the SEPIC PFC rectifier maintains external stability across both open- and closed-loop configurations when the parameters and controllers are appropriately designed. These results provide valuable insights into the design and control of SEPIC converters for power factor correction applications.